Review: Testing Sanyo’s Eneloop Low Self-Discharge Rechargeable Battery

January 1, 2007

A set of four Sanyo Eneloop AA cells in their reusable storage pack.

A set of four Sanyo Eneloop AA cells in their reusable storage pack.

Late in 2006, I found out about Sanyo’s new Eneloop Nickel Metal Hydride (NiMH) rechargeable batteries, available in AA and AAA cell sizes. Unlike regular NiMH offerings from other vendors (e.g. Duracell, Energizer, Gold Peak), Sanyo claimed the following benefits for their Eneloops:

  • Very low self-discharge rate, meaning one can charge them any time, store them until needed, and then use them.
  • Because of the previous characteristic, Sanyo sells them pre-charged, so one doesn’t have to charge them before their first use.
  • Lower internal resistance, meaning higher voltage reaching equipment that uses high currents (such as digital cameras).
Other Brands?

Since the time this article was first published in early 2007, several other vendors have started offering low self-discharge AA NiMH batteries. I’ve obtained samples of many of them and done side-by-side comparison tests. The results can be found in this article:

Pre-Charged (Low Self-Discharge) Rechargeable Battery Comparison

One apparent disadvantage of the Eneloops over normal NiMH cells is lower capacity. For the AA size, Sanyo claims a capacity of 2000mAh. Normal NiMH AAs are available with capacities of up to 2700mAh nowadays, but when you consider self-discharge rate, such NiMH cells stored for about 30 days will drop to 2000mAh.

As an avid radio controlled (R/C) model airplane enthusiast, I’ve been using rechargeable batteries for a long time. My radio equipment uses AA sized cells and my planes are powered by high-discharge Sub-C sized cells. In the R/C field, Sanyo has a long history of reliable and powerful cells, first Nickel Cadmium (NiCd) and more recently NiMH, so I was confident that their new Eneloop cells would be every bit as good as they claimed. I immediately went to the nearest Circuit City store (called The Source here in Canada) and purchased a 4-pack of AA cells. They are also available in a kit with 8 AA and 4 AAA with a charger through Amazon.

[August 2008 Update: The Source no longer carries Eneloops in Canada. However, they are now available on-line at BatteryBuyer.ca.]

Out-of-the-box Capacity

Sanyo claims a low self-discharge rate of about 15% per year (compared with about 1% per day for regular NiMH offerings). Because of this, they can pre-charge them before packaging them up and expect them to still be close to fully charged by the time you buy them. This means you can buy a pack because you need batteries now, use them, and then recharge them hundreds of times.

The first thing I did after I purchased my Eneloops was to fully discharge them in order to measure their capacity. I have a home-made computer-controlled battery charger/discharger/tester that I’ve used on my R/C batteries for years, so I used that to perform the tests. I chose a discharge rate of 1.2 Amps (1200mA), with the following results:

Measurement Four Cells One Cell
Measured Capacity @ 1.2 A 1367 mAh
Total Energy @ 1.2 A 6090 mWh 1523 mWh
Average Voltage Under Load 4.45 V 1.11 V
Internal DC Resistance 0.389 Ω 0.097 Ω

Characteristics of a 4-pack of AA Eneloop cells
discharged at 1.2A, fresh out of the package.

The discharge current that I chose is higher than that used by Sanyo to rate the capacity. Manufacturers typically use a discharge current of C/5, which means the battery capacity divided by 5. For a 2000mAh battery, this would be 400mA, or 0.4A. Discharging at higher current typically results in a lower capacity. However, I’ve done all my tests at 1.2A, so the comparisons will be valid. Here’s a graph of that first discharge:

Discharge curve of a 4-pack of AA Eneloop cells at 1.2A, fresh out of the package.

Discharge curve of a 4-pack of AA Eneloop cells at 1.2A, fresh out of the package.

The average voltage under load is only 1.11V per cell, but that’s not surprising since voltage always drops somewhat later in the discharge cycle. Since the cells started out already partially discharged, the average voltage will be lower than the expected 1.2V of a typical NiMH cell. Furthermore, the relatively high current that I used also significantly reduces the voltage. At a more typical 400mA load, the average voltage would have been 1.19V (computed using the measured internal resistance).

Available Capacity

After completing the discharge tests, I cycled the 4-pack five times. Cycling is the process of repeatedly fully discharging and fully recharging, the purpose being to exercise the battery. Most batteries require three to five cycles before they reach their rated capacity. After five such cycles, the following results were observed:

Measurement Four Cells One Cell
Measured Capacity @ 1.2 A 1848 mAh
Total Energy @ 1.2 A 8644 mWh 2161 mWh
Average Voltage Under Load 4.68 V 1.17 V
Internal DC Resistance 0.384 Ω 0.096 Ω

Characteristics of a 4-pack of AA Eneloop cells
after five discharge/charge cycles at 1.2A.

With a capacity (at 1.2A) of 1848mAh, the out-of-the-box capacity of 1367mAh represents an initial charge of 74%. This pack of AAs was manufactured in June of 2006, so they were six months old at the time I tested them. This is worse than Sanyo’s claim of 90% capacity after six months, but far better than a normal NiMH battery, which would be down to about 16% capacity after that much time. Here’s the graph of the fifth discharge/charge cycle:

Fifth discharge/charge cycle of a 4-pack of AA Eneloop cells at 1.2A.

Fifth discharge/charge cycle of a 4-pack of AA Eneloop cells at 1.2A.

Once again the average voltage is less than the typical 1.2V per cell, but this is due to the high load. With a 400mA load, the voltage would have been 1.25V per cell.

[May 2007 Update: According to Sanyo, Eneloops are only charged to about 75% capacity at the factory. This implies that the battery lost almost no capacity between the factory and my workshop.]

[September 2007 Update: I’ve just purchased an 8-pack of Eneloops that were manufactured in October 2006. I performed the same initial-discharge test on these and found them to have a capacity of 1316 mAh, which works out to about 72%. The fact that six month old Eneloops come out of the package with 74% capacity and eleven month old ones with 72% suggests that they discharge extremely slowly from the 75% initial charge.]

Self Discharge

Based on the results so far, I was sufficiently pleased with the Eneloops to start using them in my Garmin GPSMAP 60C, which sits for a week or two at a time in my flight bag, and then has to work for several hours when I take it flying. I also bought six more to use in my Nikon Coolpix 8700 camera (with the optional MB-E5700 battery pack designed to accept 6 NiMH cells).

However, I wasn’t done testing yet, so on January 14, I cycled the original 4-pack a few times to make sure it was fully charged, after which it had the following characteristics:

Measurement Four Cells One Cell
Measured Capacity @ 1.2 A 1799 mAh
Total Energy @ 1.2 A 8413 mWh 2103 mWh
Average Voltage Under Load 4.68 V 1.17 V
Internal DC Resistance 0.382 Ω 0.096 Ω

Characteristics of a 4-pack of AA Eneloop cells
after a few more discharge/charge cycles, prior
to a seven week rest.

I then set it aside in my workshop (which is usually at about 18°C or 64°F). Seven weeks later, I performed a discharge test and achieved the following results:

Measurement Four Cells One Cell
Measured Capacity @ 1.2 A 1636 mAh
Total Energy @ 1.2 A 7252 mWh 1813 mWh
Average Voltage Under Load 4.43 V 1.11 V
Internal DC Resistance 0.470 Ω 0.118 Ω

Characteristics of a 4-pack of AA Eneloop cells
after a seven week rest.

A capacity of 1636mAh is 90.9% of the 1799mAh it had when I set it aside. In other words, it lost 9.1% of its charge over the course of 7 weeks. This translates to the following results for differing time periods:

Time Period Charge Retention Charge Loss
Day 99.8% 0.2%
Week 98.7% 1.3%
Month 94.3% 5.7%
Six Months 70.2% 29.8%
Year 49.3% 50.7%

Charge retention and loss characteristics of
AA Eneloop cells for various periods of time.
(Six month and one year values are predictions.)

These results are not as good as Sanyo’s claim of 90% charge retention over the course of six months, but still far better than what one would expect of ordinary NiMH cells. Even after one year, the Eneloops would still have half their rated capacity, whereas a regular NiMH battery would be virtually dead. Notice that the predicted six-month capacity matches very closely the capacity I measured on the six month old just-purchased cells.

Sanyo doesn’t specify what the optimal storage conditions are for fully charged cells. Perhaps they’d do better stored at warmer temperatures, or maybe storing them in the freezer would be best. Additional testing is required to determine this.

[May 2007 Update: Sanyo has told me that the rate at which the battery discharges decreases over time. Thus, my extrapolation from the seven week discharge is overly pessimistic. They are also best stored at cool temperatures, as low as -20°C (-4°F).]

[September 2007 Update: It appears that Sanyo is correct about my extrapolation being pessimistic. My recently purchased eleven month old Eneloops had almost the same initial capacity (72%) as six month old ones (74%), suggesting that the self-discharge curve does flatten out at about the 75% mark.]

Here’s the graph of the discharge and charge after seven weeks:

Discharge/charge cycle of a 4-pack of AA Eneloop cells at 1.2A after seven weeks of rest.

Discharge/charge cycle of a 4-pack of AA Eneloop cells at 1.2A after seven weeks of rest.

There’s an interesting observation here. Notice that the voltage initially drops quite low, to about 4.48V, and then rises a bit to about 4.52V. This is likely caused by the initial low temperature of the cells. After about 30 minutes of discharging, they would have warmed up (from internal I2R losses).

Eneloop cells can be charged in any standard Nickel Metal Hydride (NiMH) charger, including this do-it-yourself USB-powered one.

Eneloop cells can be charged in any standard Nickel Metal Hydride (NiMH) charger, including this do-it-yourself USB-powered one.

This also accounts for the relatively high internal resistance reported by my battery analyzer. The analyzer measures the resistance either immediately, or when the battery first drops below 1.2V per cell. If it had waited until the cells “woke up”, it would probably have seen better results.

Charging

Eneloop cells can be charged in any normal slow or fast charger designed for regular NiMH cells. Personally, I would steer away from the super-fast chargers that work in under an hour (some as fast as 15 minutes). Although we use such chargers for R/C model power batteries, the cells in those batteries have a very low internal resistance (typically about 0.004Ω per cell) and can handle the high charge rates. With the approximately 0.1Ω resistance of the Eneloops, an 8A charge rate (which is needed to produce a 15 minute charge) would cause about 6.4W of heat to be generated in each cell, which will make them very hot.

Unlike traditional NiMH AAs, Eneloops are a good choice for remote controls.

Unlike traditional NiMH AAs, Eneloops are a good choice for remote controls.

Like any rechargeable battery, Eneloops should not be left connected to a low current “wall-wart” type slow charger indefinitely. Fortunately, the main reason for doing this has been to ensure there are always charged batteries on hand. With the Eneloops’ low self-discharge rate, this is not really necessary.

Eneloops are probably best charged with a 1 to 5 hour quick charger (like this do-it-yourself USB powered one) that automatically turns off on charge completion, and then removed and stored until needed. If left unused, they can be recharged every few months to top them off.

[May 2007 Update: Sanyo will be introducing their own USB powered Eneloop charger on May 21.]

Applications

Traditionally, I’ve used rechargeable cells in equipment that gets used for a short period and then sits around until its next use. I’d recharge the battery just before using it again. For other battery powered devices, such as wall clocks, flashlights, and TV remotes, disposable alkalines made more sense because rechargeables would run down more quickly from self-discharge than due to the power needed by the device.

Eneloops are also suitable for long-running devices like this battery operated clock.

Eneloops are also suitable for long-running devices like this battery operated clock.

With the Eneloops still maintaining about half their capacity after a year, it’s now feasible to use them in such long-term applications. When they do run down, I can just insert freshly charged ones and recharge the old ones. This has enormous potential environmental benefits, since it can virtually eliminate the need for disposable batteries.

Because of their low internal resistance, Eneloops are also ideal for high-current devices. This is the battery pack for my Nikon Coolpix 8700 digital camera.

Because of their low internal resistance, Eneloops are also ideal for high-current devices. This is the battery pack for my Nikon Coolpix 8700 digital camera.

Like regular NiMH AA batteries, Eneloops are also a great choice for high-current devices like digital cameras that like to eat batteries. I recently purchased a Nikon MB-E5700 external battery pack for my Coolpix 8700 camera. This attaches to the bottom of the camera and holds six AA cells. I put a freshly charged set of Eneloops in them before our trip to Florida. One and a half months and 160 photos later, the camera’s battery indicator is still showing “full”.

[May 2007 Update: I finally had to recharge the Eneloops after three months and 320 pictures.]

At this point, Eneloop technology is still relatively new. It remains to be seen how long they will last. Just because an Eneloop cell might last a year in a clock before needing recharging, and it can be recharged hundreds of times, doesn’t mean it will last hundreds of years. All battery technologies wear out, even when their full capabilities are not being used. However, these are a form of NiMH technology, which is very reliable and stable. I have a 10 year old NiMH battery that can still achieve about 85% of its original capacity, so I have confidence in the Eneloops’ longevity.

Where to Buy Them

Sanyo’s Eneloop batteries are available from a number of North American retailers including Circuit City, Fry’s Electronics, and the Ritz Camera Centers family of stores. They are also available on-line in the USA through Amazon.com:

A Response from SANYO

About a month after first posting this review, I received a very nice e-mail from Mr. Taetow, Vice President General Affairs at SANYO Component Europe GmbH, expressing appreciation for my independent review and addressing a few points, which I’ve summarized below:

  1. The Eneloop batteries are sold charged, but not necessarily 100% fully charged. In Europe we charge them about 75%. I am not sure to which degree they are charged before being sold in Canada. Thus it is rather vague to estimate the discharge rate by calculating backwards to the production date. Also, the storage conditions (transport, warehouse, shop, etc.) are unknown (see point 3 below).

  2. Several long term tests have shown that the self-discharge rate decreases over time. This means that Eneloop batteries discharge relatively fast at the beginning and relatively slower the longer you store them. To get real (long-term) test results, you have to store them and wait. An estimation of long-term discharge rate by extrapolating short term storage results is not correct and leads to rather poor results. This may explain the differences you have seen.

  3. Storage temperature is of high importance if you measure self-discharge rate. Higher temperatures substantially increase self-discharging. It is best to store Eneloops as cool as possible to keep the charge in the battery. As a rule-of-thumb, every 10°C increase in storage temperature is equivalent to doubling the storage time. Some R/C pilots in Europe put Eneloops in the freezer, with rather good results.

In short, the Eneloops may be even better than my tests show. Without more testing, I can’t confirm this, but my results show they are already far better than traditional NiMH rechargeables.

Mr. Taetow also saw my home-made USB Powered AA Charger (which can be used for Eneloops) and informed me that Sanyo is introducing their own USB powered Eneloop charger, scheduled for release on May 21, 2007.

May 2007: Comparison with Traditional NiMH Rechargeables

Over the course of the last seven weeks, I repeated the above experiments with a set of 2500mAh NiMH cells of a well respected brand. After an initial set of four cycles, these had the following characteristics:

Measurement Four Cells One Cell
Measured Capacity @ 1.2 A 2172 mAh
Total Energy @ 1.2 A 9745 mWh 2436 mWh
Average Voltage Under Load 4.49 V 1.12 V
Internal DC Resistance 0.430 Ω 0.108 Ω

Characteristics of a 4-pack of AA traditional 2500mAh
NiMH cells after four discharge/charge cycles, prior
to a seven week rest.

Seven weeks later (less two days), I performed a discharge test and achieved the following results:

Measurement Four Cells One Cell
Measured Capacity @ 1.2 A 1360 mAh
Total Energy @ 1.2 A 5647 mWh 1412 mWh
Average Voltage Under Load 4.15 V 1.04 V
Internal DC Resistance 0.499 Ω 0.125 Ω

Characteristics of a 4-pack of AA traditional 2500mAh
NiMH cells after a seven week rest.

This works out to a capacity retention of 62.6% (a loss of 37.4%) over the course of 47 days, which translates to the following results for differing time periods:

Time Period Charge Retention Charge Loss
Day 99.0% 1.0%
Week 93.3% 6.7%
Month 73.8% 26.2%
Six Months 16.2% 83.8%
Year 2.6% 97.4%

Charge retention and loss characteristics of
traditional 2500mAh AA NiMH cells for various periods.
(Six month and one year values are predictions.)

Although these cells start out with about 20% more capacity than the Eneloops, they lose their capacity more quickly. After only three weeks of storage, the Eneloops have more capacity remaining. After about 3½ months, the Eneloops will have twice the capacity of the traditional cells.

After only three weeks of storage, traditional 2500mAh NiMH cells will have less capacity remaining than 2000mAh Eneloops.

After only three weeks of storage, traditional 2500mAh NiMH cells will have less capacity remaining than 2000mAh Eneloops.

[September 2007 Update: My recent experience purchasing eleven month old Eneloops that had the same initial charge (72% of rated capacity) as six month old ones (74%) suggests that the the Eneloops’ self-discharge curve flattens out. The above graph should probably look approximately like this:

Revised graph based on experience with eleven month old Eneloops. Even better than previously thought!

Revised graph based on experience with eleven month old Eneloops. Even better than previously thought!

]

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Leave a Comment

217 Comments

  1. Tim
    October 17, 2007

    What a fantastic and VERY helpful review! Thank you for doing all of this work!

  2. Aidan Hart
    October 22, 2007

    A technically brilliant and customer helpful review; well done. Aidan

  3. PenaParaati
    October 31, 2007

    Nice! Thanks for a good review!

  4. Jeff
    November 02, 2007

    We have a digital camera in the office that we use on occasion, but it usually sits unused for months at a time. We’ve gotten caught a few times now with dead batteries, so this looks like a good solution. Thanks for the thorough review!

  5. stolennomenclature
    November 15, 2007

    I do not understand your comments re using a fast charger with the eneloops – the figures don’t seem to add up. You seem to me to be suggesting that the entire 6.4 watts of energy going into the battery is being dissipated as heat, but this is not so. Only a portion of this energy is lost as heat, most of it is being used to charge the battery. Surely therefore perhaps at most about 1 watt would be converted to heat.

  6. Stefan Vorkoetter
    November 15, 2007

    StolenNomenclature, the 6.4W is only the amount being converted to heat. Those 6.4W are from the current squared, times the internal resistance (i.e. 8A × 8A × 0.1 Ohms = 6.4W).

    The total amount of energy going into the battery is the current going in times the voltage going in, the latter of which equals the battery’s resting voltage at the current state of charge, plus the current going in times the internal resistance.

    So assuming the battery is at 1.2V and the internal resistance is 0.1 Ohms, then at 8A, the charger has to be putting out 1.2V + (8A × 0.1 Ohms), which is 2V. So the total energy going in will be 8A × 2.0V, or 16W.

    So there’s 16W going in, of which 9.6W is charging the battery, and 6.4W is being dissipated as heat.

  7. Mick
    November 16, 2007

    Great review. I’ve just bought some Panasonic’s INFINIUM batteries that probably use the same technology. I’ll use them for my seldom used digital cameras and torches. It’s great to finally have an AA type rechargeable battery that can be trusted to hold it’s charge for time when it’s needed.

  8. Ron
    November 27, 2007

    Great review. I just bought Costco’s Eneloop kit. Consists of 8 AA, 4 AAA, 2 each D-cell and C-cell adapters plus charger.

    Only complaint: Charger works on 110V only. This limits usefulness for foreign travel. Seems a shame, since so many electronics now work on 110 and 220V.

    Ron

  9. Jim
    December 03, 2007

    Have a new Canon PowerShot A570 IS camera that goes through standard AA alkaline batteries quickly. Canon telephone rep did not recommend any particular brand, so I’m going to try Sanyo’s eneloop. Thanks for the research!

  10. Ron
    December 06, 2007

    Regarding charging with 240v. Does anyone know if a Panasonic charger Model BQ-390 (input 100-240v 8W; output DC 1.5v 550 mA X 4) would be suitable for the Eneloop batteries? I have a couple of these chargers and I would like to use them for European travel.

    Thanks, Ron

  11. Stefan Vorkoetter
    December 06, 2007

    Ron, based on the information I’ve found about this charger, it should be perfect for charging the Eneloops. It should take about 4 hours to fully charge a set of 4 Eneloops.

  12. Tad
    December 08, 2007

    Thanks for the review. I just purchased the basic 2-pack w/ charger from the local Ritz Camera store.

    What I found interesting was that the charger looks identical to the one that came w/ the el-cheapo batteries that originally came with the camera- a wallwart branded Fujifilm instead of Sanyo and with a different Model no. Otherwise, looks exactly the same on the exterior, even down to the printed labels on the back.

    These will be used in a Fujifilm Finepix E550. May post update- depending on how things go!

    Thanks again for the in-depth review.

  13. Marcelo Versiani
    December 12, 2007

    Thank you! It’s really hard to choose among so many available batteries in the market.

    I have some Eneloops, and just love the way they retain the juice. My other batteries are kept in the charger until the day I will use them.

    One question. Is it always better to refresh a half used battery? Or should I only complete its charge?

    Thanks again.

  14. Alisa
    December 12, 2007

    Thanks for such a thorough testing and review of this product! I just bought a pack of these batteries and was curious if their product was a solid at the marketing on the package. Looks like I may be quite pleased with these batteries after all. Thanks again!

  15. Stefan Vorkoetter
    December 12, 2007

    Marcelo, if you’ve got a partially used battery, there’s no harm in recharging it so long as you’re using a charger that will stop when the battery is full. Having said that however, it is worthwhile to full deplete the batteries from time to time before recharging.

  16. Con Papas
    December 15, 2007

    Another "Great Review" comment. Well done, keep up the great work and thanks.

  17. David
    December 16, 2007

    I am also an RC flyer and these batteries have extra long life which means more flying time at the RC field. I have had excellent results making my own TX and RX battery packs for this purpose.

    I also use these batteries exclusively in my high drain digital camera with excellent results. The biggest performance increase was noticed with the shorter flash recharge time, especially after prolonged use.

  18. chobo
    December 17, 2007

    Regarding the "self discharge curve", I think you have already corrected yourself, but I would still like to point out that by "extrapolating" a 7-week test data to a year, you are assuming a linearity in the self discharge curve, which should generally follow a logarithmic curve. For example, if you time how fast hot water cools, it follows a logarithmic, not linear, curve. Having said that, the best data, of course, will come from actual testing — like what you did, which is thorough, interesting, and commendable!

  19. Stefan Vorkoetter
    December 17, 2007

    Chobo, you are correct that the self discharge would be logarithmic, not linear. However, when I extrapolated from the seven week data, I did fit a logarithmic curve to the data points (otherwise my self-discharge graph would have been a straight line, which it isn’t if you look closely). The comment from Sanyo suggests that it’s even better than that, which my revised graph reflects (I used a straight line there because that graph is just a conjecture based on Sanyo’s feedback).

  20. erkkimerkki
    December 18, 2007

    Hello and thanks for the excellent review!

    Now that you have the email address of a Sanyo Europe employee, could you please ask him, if there are any differences in Eneloop batteries and conventional ni-mh batteries used in cold temperatures, let’s for example -10 or -20 degrees celsius. So far we know that we should store them in freezer (-18 degrees celsius), but how about using them? Traditional Ni-mh rechargeables don’t cope well here at the Arctic Circle in Northern Europe. Thank you very much!

  21. Stefan Vorkoetter
    December 19, 2007

    Erkkimerkki, here’s the official SANYO response:

    Eneloop is a NiMH battery which is optimized for low self discharge current and long life-time (i.e. number of cycles). It has not been optimized for low temperature operation. So, basically we would not expect, or even claim, a better performance at low temperatures than our normal NiMH batteries.

    However, some independent tests suggest that the Eneloops do work better in cold weather. For instance, see the following German forum: http://www.rc-network.de/forum/showthread.php?t=59430&page=2. In their tests at -24°C, the Eneloops discharged at 2A put out about 1400mAh.

    I too have found that the Eneloops work better in my GPS in cold weather. Regular NiMHs used to last about half an hour (in the same GPS where they’d last all day in the summer). The Eneloops so far haven’t suffered from this problem.

  22. chris miller
    December 21, 2007

    Thanks for your in depth analysis. Great stuff.

  23. loree
    December 21, 2007

    Read your thorough review with great interest, as I’m trying to learn enough about the various batteries to see which ones I can use in my new Kodak Z812IS (inexpensive but great little camera).

    The specs call for either non-rechargeable CRV3, rechargeable KLIV-8000, or AA lithium batteries. Obviously, all lithium (and Kodak brand).

    Are NiMh batteries acceptable in place of the lithium?? I’ve read quite a lot about both types, but nowhere does it actually say they’re interchangeable. (Perhaps that knowledge is just TOO basic?)

    I’d also read somewhere that one needs to be careful not to have too much voltage (something about 3V?) — is this an issue with the Eneloop for my situation?

    The novice here will appreciate any good feedback. Thanks so much!

  24. Stefan Vorkoetter
    December 21, 2007

    Loree, there’s no way for me to know for sure, but a pair of Eneloop AA batteries might work. You see, AA "lithium" batteries aren’t really lithium batteries, but rather lithium-enhanced alkaline batteries. A real lithium battery like the CRV3 puts out 3V, whereas a AA "lithium" battery puts out only 1.5V. Since the camera takes two of them, that adds up to 3V.

    The problem is that an Eneloop AA (or any NiMH AA) puts out only 1.2V, which may or may not be enough for the camera. See if you can borrow a pair of NiMH AA batteries from a friend (be sure they’re freshly charged). If they work, the Eneloops will work.

  25. loree
    December 21, 2007

    Thank you Stefan for your lay-person answer on the batteries! It was the explanation I was hoping for!

  26. D.D.
    January 11, 2008

    I think your research on this is great. I was wondering if you have done any similar research on the Rayovac Hybrid batteries. http://www.rayovac.com/recharge/index.shtml. I believe that they are similar technologies. I was also curious as to your opinion on Rayovac batteries as a brand as opposed to other rechargeables.

    Thank you.

  27. Stefan Vorkoetter
    January 11, 2008

    D.D., I haven’t had any experience with the new Rayovacs, and I haven’t used any other Rayovac rechargeables either, so I don’t really have an opinion on them. Sorry.

  28. G
    January 30, 2008

    I’m extremely happy with the information you provide. I’d heard about the Sanyo batteries, but I didn’t know, and I was referred to your site. All I can say is amazing work. Keep it up! We’re all counting on you to give us the obviously important information no other sites seem to think is obvious!

  29. Greg Conquest
    February 02, 2008

    Memory Effect?

    Great review. Thank you for the effort put into it. How about memory effect on these batteries? Do they suffer from memory effect less than other NiMH rechargeables?

  30. Stefan Vorkoetter
    February 02, 2008

    Memory effect? No such thing, at least not in consumer applications. Real memory effect occurs only if a battery is charged and discharged in an exactly repeating cycle (like in a satellite that goes around the Earth every 90 minutes). The problem only affected NiCd batteries, not NiMH.

    However, there is a problem called "voltage depression" wherein the capacity of the battery (in mAh) remains the same, but it delivers that capacity at a lower voltage. This makes your electronic equipment think the battery is dead sooner than it actually is, and this is often mistaken for "memory effect".

    What causes this voltage depression? Overcharging. Namely, leaving the batteries connected to a low current overnight charger indefinitely so that you always have a charged set of batteries ready to go.

    I suspect that the Eneloops would suffer from the same problem if you treated them the same way, but there is no need to leave them connected to such a charger, because they stay charged. Just charge them with a smart charger, take them out, and store them until you need them.

  31. Pat
    February 14, 2008

    Ron: The Sanyo Eneloop kit I bought from Costco tonight (2/13/08) has a charger that is rated 100-240 V, 50-60Hz (from the back of the charger). With a European plug adapter kit the charger should work fine.

  32. Johnny
    February 22, 2008

    I use six eneloops in a Coolpix 8800 battery pack, similiar to yours. So far, in one charge it takes many pictures at high quality settings, as well as powering the electronic viewfinder and review screen, and deleting my reject pictures, etc. Much, much better than the proprietary Lithium Ion Nikon battery EN-EL7 for the 8800.

    Quote from your Dec 2007 posting: ‘it is worthwhile to fully deplete the batteries from time to time before recharging.’

    How to do a full deplete? Special equipment?

    How frequently?

    How is fully depleted measured?

    How to determine remaining capacity after storage?

    Is there a website with detailed information on using and charging/discharging these batteries for best performance?

    Thanks for a great write-up that helped me to decide on the eneloops.

    Johnny.

  33. Stefan Vorkoetter
    February 25, 2008

    The easiest way to fully deplete a battery is to run it down until the device it’s in shuts off. As long as it’s an electronic device that has an automatic low-battery shutoff, this will be fine. Don’t do it in a flashlight, which will discharge the cells right to zero, which is bad for them.

    The way to determine the capacity is to discharge the battery at a known current until fully depleted (i.e. down to about 1V per cell), and multiply that current by the number of hours it takes to do so. This is most easily done using special equipment, such as the device I describe at http://www.stefanv.com/electronics/battman2.html

  34. Andrew Brett
    March 31, 2008

    As a wholesaler of this great product it is good to see a layman’s explanation of it benefits and attributes. The more people understand it, the more likely they are to source it. In Australia the Battery World chain of stores (90 in Aust) stock both Eneloop batteries and chargers. Keep up the interesting and informative work.

  35. Bill Todd
    April 26, 2008

    I’ve just acquired some eneloops and look forward to using them more flexibly than the NiMH batteries that I’m used to. One potential application is as a supplementary external battery for my laptop.

    However, that will require 12 of them in series, and the documentation that I received with the product indicates that no more than 9 should be used in series. No explanation is provided, but I suspect that it may be related to the possibility of polarity reversal due to differing discharge rates (or amounts of initial charge – though I have seen conventional NiMH batteries sold in similar series configurations for this purpose and of course for 18 v. power tools, which presumably require 14 or 15 in series).

    My laptop cuts over to internal power when the external voltage drops to about 12.5 v., which may be high enough not to have to worry about the problem (unless the capacity of the cells varied pretty wildly: if one of them reached 0 v. then the others would s

  36. Stefan Vorkoetter
    April 27, 2008

    I didn’t see any notes anywhere limiting these to 9 cells in series. Polarity reversal can happen whenever you have two or more cells in series, although the more cells there are, the more likely that one cell will reach zero before the equipment that it’s in thinks the battery is dead.

    As long as you take care not to discharge the series wired battery too low, there’s probably little risk of cell reversal. Perhaps you can build a voltage monitor circuit into your external battery, to cut off the power once the voltage drops below about 13.2V or so (1.1V / cell).

  37. Avinash Lewis
    May 09, 2008

    Hi, i have virtually used all sort of batteries Nicads to Li.i preferred Camelions Nimh to others…but as said they have high discharge rates…Eneloops are very good in terms of discharge. I use a Nikon L11 very heavily round 600 shots at a time….but is there a higher capacity available say like 2500 instead of 2000 mah in Eneloops?

  38. Stefan Vorkoetter
    May 09, 2008

    Avinash, an advantage of low self discharge is that you effectively *do* have higher capacity. Sure your Chameleons might have 2500mAh when they’re fresh off the charger, but will they still have that a day or two later? Probably not.

  39. Mary L Nags
    May 21, 2008

    Just bought this brand w/charger and 8 AA, 4 AAA, and bodies (2 each C and D size) to insert AA batteries in a kit. Price aprox $26 and tax @ Walmart. Glad to know it will be a good investment. Plan to purchase one for each of my 4 children if it’s as good as it looks.

  40. Erkan
    May 23, 2008

    Stefan, you wrote: "Perhaps they’d do better stored at warmer temperatures"

    You better delete this as it is an awfully wrong idea.

  41. Erkan
    May 23, 2008

    Stefan, you wrote under the table: "(Six month and one year values are predictions.)"

    You better correct your predictions as they are awfully wrong.

  42. Stefan Vorkoetter
    May 23, 2008

    Regarding storing at warmer temperatures, you’ve quoted me out of context. The rest of the sentence says, "or perhaps they’re best stored in the freezer". The point was that Sanyo didn’t make it clear what the optimal storage temperature was. And in the next paragraph, I show the reply I got from Sanyo on this.

    Regarding the predictions, they are based on the measured rate of discharge (and the assumption that the rate decreases). They are not wrong; they are predictions. Also, near the end of the article, where I provide an update, I give more information as it became available to me. I don’t believe in going back and changing what was written before (unless it was a simple spelling or grammatical error).

  43. Daniel F. Meier
    June 21, 2008

    My personal experience with using long-charge-retention NiMH batteries with "15 minute" chargers is that they perform superbly. I have experience with two chargers, the Energizer and the Dynex (Best Buy house brand, now (sadly!) discontinued). With regular Energizer 2500 mah cells, the Energizer charger would usually get them very hot (wouldn’t actually burn you, but you want to drop them pretty quick), and the Dynex charger would usually just get them uncomfortably warm. With the Eneloop AA cells and the Duracell AAA cells (can’t get eneloop AAA’s locally), the Energizer charger gets them just comfortably warm, and the Dynex charger gets them just barely perceptibly warm. This suggests that, for whatever reason, your DC resistance measurements may be pessimistic, at least as far as the effects of charging at 7 amps (AA) and 4 amps (AAA) (the stated charging currents for both chargers) is concerned.

    CAVEATS: I haven’t done any testing for capacity, so I don’t know what effect the repeated 15 minute charging is having on their capacity or on their cycle life. Also, I don’t know if one charger is charging them to a higher capacity than the other.

  44. Gaye from Darwin Australia
    June 26, 2008

    I have just purchased the Eneloop AA & AAA batteries for my household remotes, cameras and computer mice if that is okay??. THEN i read your wonderful explanation of everything and i am happy that i made the RIGHT choice thanks for your knowledge keep up the good work

  45. Friendly reader
    July 31, 2008

    I am very impressed by your thoroughness and attention to detail. Excellent review!

  46. Breezy
    July 31, 2008

    Wow, extremely informational article. I’m very impressed. Eneloops are hard to find in stores around me, so I get Duracell Precharged Rechargeables and they’re very similar and work great for me

  47. Ed from Ohio
    August 14, 2008

    I have recently learned about these Eneloop batteries. Obviously, I’m really late to the party.

    For you shoppers, Circuit City seems to be closing out the Eneloop line and is selling their 4-pack of AAA now for $6.59.

    The best price I could find on the AA 4-pack was at HH Gregg, for $7.99. Web sites were all significantly more.

    There are also some other brands that are starting to raise the mah rating, such as Maya.

    Lastly, I would recommend a good charger. At Thomas Distributing, they carry the La Crosse BC-900 charger for less than $40 and it even comes with a case, 2 sets of batteries and C/D cell adapters. That charger is simply awesome!

  48. John Green
    August 14, 2008

    Thanks for your informative article. What I’m mostly interested in is how long a set of fully charged Eneloop AAs will last in a digital camera (let’s say Canon A720IS) WHEN IN CONSTANT USE as compared to a fully charged set of Energizer 2500 mHA AAs. Your article mostly touched on the relative "shelf staying power" of the Eneloops and just a little on how they performed in your camera, but no comparison like I’m looking for. Picture me on a trip, I’m out in the boonies, I’ve got two fully charged Eneloops in my A720, I’m going to take as many shots as I can, even if it means 400 or just maybe a ton of video. Shelf life wouldn’t matter in such a scenario.

    I’ve read in other reviews that, in fact, the Eneloops perform less strongly in a head-to-head comparison like I’m seeking. To me the fact that they stay charged while not in use is another discussion. Thanks again.

  49. Stefan (but not the author)
    August 22, 2008

    Great article! Just wanted to point out for any Canadians looking to buy Eneloops that you can find them quite cheap at Costco (they sell a large kit with charger and about 20 assorted AAA, AA, C, and D batteries for $60) and costco.ca, and ncix.com has them on their sale page virtually every week (click the sale banner on the home page) for 4 packs of AA or AAA at $10 and a charger and set of 4 AAs for $30.

  50. Caesar Wong
    August 25, 2008

    Brilliant review. I learned a lot from your article not only about the product being reviewed, but about rechargeable batteries and chargers in general. Your writing style is clear and easy to understand – you should be a professional reviewer!

  51. Tom
    October 08, 2008

    This review led me to purchase an Eneloop Powerpack from Costco, a four battery charger and some AA and AAA batteries with adapters for C and D cells. Since then I have purchased a hundred more batteries. Eneloops are the BEST way to save money and help the planet today. I do not buy any disposable batteries now. I advocate requiring a deposit on disposable batteries, like disposable containers. The most complete and competitive Eneloop seller on line, to my knowledge, is depoteco.com, my source for Eneloops now. Sign in before starting order for special prices. The blog has a lot of information.

  52. Goran from Belgrade, Serbia
    November 23, 2008

    Thank you Stefan for such informative article! I just wanted to check the story from my local pro-photo store in Belgrade ("BM Foto") about Eneloops not losing their capacity, and what I’ve got from your article is much, much more useful information.

    It may be interesting, the guy from the above mentioned store told me also that most of the pros uses Eneloops. It’s obviously why.

    Best regards!

  53. Gamer
    December 23, 2008

    Very nice and thorough review. I just purchased the Costco Power Pack and plan to use the batteries in the Wii remotes that the kids will open on Christmas morning. I hear the eneloops are perfect for this application.

  54. Alexis Castro
    January 13, 2009

    Hello sir, I’m new with using eneloop batts, and so far I am satisfied with it.. I have the sanyo ni-mh batt charger for 4 pieces, and I’m wondering how long it will take for me to fully recharge the batt.. Its my first time to recharge it btw.. I’m sorry if this is more like a question and not as a comment

  55. Vivona
    January 29, 2009

    I just came across your excellent work on Eneloops. Looks like in late 2006 we both came to the same conclusion, though my study was based on the need for a rechargeable battery that would keep its voltage above 1.0 volt for most of the discharge curve. You can read all about my Eneloop study and results at http://www.epinions.com/content_309637189252

  56. Ian Jenkins
    February 18, 2009

    Great work, a very clear analysis. However this technology is now common amoung battery makers. Can you also test Maha Imedian and Matsushima low discharge batteries, both superior brands.

  57. Stefan Vorkoetter
    February 18, 2009

    Ian, yes this technology is now commonplace, but it wasn’t when I wrote the article. I’m currently in the process of preparing my report on a number of other brands, although the two that you list aren’t available to me here in Canada.

  58. Dan
    March 03, 2009

    Hi there, excellent article. I was reviewing the current prices for Sanyo Eneloops @ BatteryBuyer and CanadaComputers. The prices have indeed skyrocketed. They are now $18.00 [Canadian] for a pack of 4 AA. I recall buying a pack of 8 AA eneloops at The Source for about $15.00 [Canadian] at the time. It was likely a sale and prior to the popularity of lsd cells but still the regular price was ~ $10.00 at the time.

    Would you recommend Duracell Pre-charg., Kodak Pre-charg, or Rayovac Hybrids? I can find these 3 at my local Wal-Mart for slightly less than eneloops.

  59. Stefan Vorkoetter
    March 04, 2009

    Dan, I haven’t tested the Kodak offering, but I tested Duracell, Sony, and Rayovac in my low self-discharge battery review. Regarding the prices, The Source was having a clearance sale. The regular price for 4 AA Eneloops at the source was $19.99.

  60. Aaron Dalton
    March 12, 2009

    Prices have come way down on these batteries.

    You can get 4 AA Sanyo Eneloop batteries plus the charger right now for less than $19. Here’s the link – http://tinyurl.com/d2tfda

    – Aaron Dalton, Editor, http://1GreenProduct.com

  61. Ali Makooie
    March 13, 2009

    I have been using Sanyo rechargeable batteries for almost 4 years in my camera. My first four batteries lasted 4 years until I lost my camera and I take almost 1000 photos a month. I have been extremely happy with my Sanyo batteries. I just bought a pack from Costco that comes with cool C and D adaptors !!! using AA batteries.

  62. Charles Smith
    March 22, 2009

    I just ordered a set of these based off your review. Thanks for the diligence in reviewing these batteries.

  63. Murali
    April 13, 2009

    Thanks for the review, Just got this off costco.. was not sure how these performed.. but this review surely helped..

  64. Onur D.
    May 22, 2009

    I had purchased a "power pack’ from costco today and your review just confirmed that I made the right choice. Now I will be purchasing additional spare AAA eneloop batteries based on your review. thx

  65. yocki
    June 15, 2009

    hi.. nice to read your article. I need to ask your decision wether to buy Eneloop or just normal NiMH batteries. which one is better, a 2700mAH batt or eneloop ? what is the size of mAH got to do with the battery ? the bigger the mAH the more longlasting the battery ? thanks.. please send me your answer through my email, yocki@hotmail.com PS: i wanna buy a suitable rechargeable battery for my 5Mp digicam. thanks alot.

  66. ed okie
    June 22, 2009

    Eneloops are the-real-deal! Far better than many other allegedly higher-powered batteries. Staying power is the key difference over others. I use a Canon 580 strobe irregularly (4 eneloops) and it is has never let me down even after being on the shelf for a month or more – always ready to go. Other batteries (4 different sets/brands)… always were dead as a doornail or virtually useless. Paired them up with a new LaCross BC-700 charger; excellent combination.

  67. Chris Hunt
    June 30, 2009

    Excellent article, very informative. If all scribes wrote like you the whole world would be smarter. Thanks.

  68. Barry
    July 10, 2009

    The first rechargeable batteries that actually do a decent job! Many thanks for your very helpful review. As I live in the Canary Islands, would I be better leaving them in the fridge or freezer, do you think?

  69. Gurudath
    August 04, 2009

    I’ve a very good experience with eneloop cells which I’ve been using since 2005. Since then, I’ve never gone for any other type of rechargeable cells.

  70. David
    August 16, 2009

    I had planned on using these cells (enelooop) for R\c receiver packs. However, after reading the NiMh\NiCd tech tips and support faq’s on Red’s Battery clinic I am a little concerned about the negative comments as to their suitabiliy for R\C use. There seems to be a difference of opinion regarding the impedence of these cells. Any comments please? Thx.

  71. Stefan Vorkoetter
    August 16, 2009

    I haven’t used the Eneloops as R/C receiver packs, because all my planes are BEC equipped. The internal resistance of the Eneloops is a bit higher than most NiCds and NiMH, so Red might have a point, but I don’t believe they’re as fragile as he makes them out to be. (I’ve been charging the set of six Eneloops that I’ve used in my Nikon for the last three years at 1.2A with no problems; they still last 3 months and 300 photos between recharges.)

    I have recently replaced the 400mAh AAA NiMH batteries in my Braun shaver with 800mAh AAA Eneloops and have noticed a slight reduction in "shaving power", but I can live with that because it means I can go on a 10-day business trip to Europe and not bring the charger and AC plug adapter.

  72. captain tanqueray
    November 07, 2009

    I saw a 4-pack/charger set on clearance at a major chain store phasing them out to go exclusive to Energizer’s rechargeable. I probably wouldn’t have bought them if they weren’t 1/2 off. I also wouldn’t have bought them if I had never heard the name before (no trust in rechargeable batteries at this point, long story(s)..). I went in for some Energizer’s lithium battery for use in a Nikon Speedlight SB800, which goes through about a battery a minute (not really but kinda). It’s now been 19 months of cutting 10-20 bucks off my photo shoots (2 or 3 multiple hour events a month) on the same set of Eneloop AAs. Their reliability is A+ and durability is exceptional. They were in a office fire 3 months ago, in a room that melted two of my printers and my desktop PC. They were plugged in on a wall that was charred on the other side, two or three feet from the batteries. Not only do they still work, but for the last month they’ve been working 1.5 hour shifts, 4 times a week. I’m in awe of these batteries and couldn’t recommend them enough.

  73. Gedrod the Mighty
    November 10, 2009

    Thanks for an comprehensive, informative and honest review

  74. Frank Manders
    December 07, 2009

    Nice to see my feelings for these cells confirmed.

    Over a year ago I last charged my digital camera, in which sit a pair of two year old Eneloops. The camera still works although it is now in the red.

    And for RC flying I use almost nothing else. For .46 to .60 planes they work perfectly. Also I made transmitter packs. I charge both once per two months or so.

    I saw everything tested here in the field, but no measurements. So this is a nice confirmation.

    Thank you for the review.

    Frank.

  75. Doug Simpson
    December 31, 2009

    Stefan,

    Thanks so much for your low self-discharge reviews.

    Below is an excerpt of your paraphrase of Sanyo’s comments. My suggested fix in parens, based on context.

    "As a rule-of-thumb, every 10°C increase (decrease) in storage temperature is equivalent to doubling the storage time. Some R/C pilots in Europe put Eneloops in the freezer, with rather good results."

    I found Sanyo sanction of low temps down to -10 C here

    though http://sanyo.com/eneloop/pdf/enebook_e20090402.pdf

    though the reference was for usage, not storage.

    Freezer seems overkill, but I might try the fridge.

    Doug

  76. Geoff
    February 01, 2010

    Thanks for the great review. I have seen some other reviews saying that the C and D sleeves do not work very well because the batteries are not strong enough for some devices. We are expecting our first child and are looking for a full set of rechargeable batteries and charger for AAA, AA, C and D. Would you recommend these for high powered devices like a baby swing that uses 4 D batteries? Thanks again,

  77. Stefan Vorkoetter
    February 01, 2010

    I haven’t tested them in really high powered devices. I don’t know how much current a baby swing needs, but I suspect it’s quite high. I’d buy the Eneloops and try them in the swing, and if they don’t cut it, use them for other stuff that they’re better suited to, and buy another brand of D sized rechargeables. Careful though, some D sized batteries basically are wrapped up AA size. A real D battery will have at least 4000mAh capacity.

  78. Tom
    February 20, 2010

    Geoff this is the same reason i started looking around the net for reviews seems all the baby toys have batteries these days. After a night of looking im going to be giving these a try. and like he said even if they don’t work for the swing and such i have plenty of other things to use them in.

  79. Tom
    February 20, 2010

    Geoff this is the same reason i started looking around the net for reviews seems all the baby toys have batteries these days. After a night of looking im going to be giving these a try. and like he said even if they don’t work for the swing and such i have plenty of other things to use them in.

  80. Peter C
    March 10, 2010

    I have some Eneloops (4 AA) and a Canon SX110IS camera (takes 2 AA). Charged them a few times and left them in camera for about 3 months. Took camera out and battery indicator on camera said no juice in them. Did allow me to take 2 pics. Friend has same eneloops and a slightly different Canon (newer) model and same thing occured. So for me it is not holding charge. I am using the NIMH Sanyo charger that came with the 4 AA Eneloops.

    What gives?

    Thanks Peter pcumming@yahoo.com

  81. Stefan Vorkoetter
    March 10, 2010

    It might be that the Canon actually draws some power from the batteries even when it is off (maybe to run the clock). In my Nikon, if I put in freshly charged Eneloops, leave it for three months, and then turn it on, I can still take hundreds of pictures.

  82. Bill Blanchard
    March 13, 2010

    Hi, Thanks for all the time and research you put into your battery work. I have to buy about 16 AA rechargeable batteries to power my Nikon SB 800 flashes. So I need the best I can get. From your research it looks like the Sanyo Eneloop may be my choose. I just have to do a bit more research before I buy them. Any advice would be greatly appreciated. Thanks. Bill Blanchard http://www.sillblanchardphoto.com

  83. Stefan Vorkoetter
    March 13, 2010

    Well, I’d recommend them whole-heartedly, but why don’t you buy a pack of 4 and try them before investing in all 16 (I assume you don’t need all 16 at once).

  84. Randy Mickel
    April 10, 2010

    Your article seals the deal. I’ve been looking for a good, all-around, AA battery for cameras, GPS & etc. I’m now confident Sanyo makes that battery. Thanks for great review. Very thorough & very convincing!!…………..Randy

  85. Lloyd
    April 23, 2010

    Please read the following excerpt from a "review" on amazon.com regarding the eneloop batteries. I want to buy the eneloops for my little Canon 270ex flash unit, a Canon 610 point and shoot and small flashlights. I’m no expert so please comment on this criticism….Thank you!:

    These are LR03 1.2V batteries not HR03 1.5V batteries. That said most of the products out there require a HR03 1.5V AA batteries rating. What this means is that the LR03 1.2V batteries (which these are) will work but the will not power your electronics to its full potential in addition they will loose power much faster than the HR03 1.5V AA rated batteries. Not all AAA, AA etc batteries are the same in terms of voltage they are only the same in terms of size.

  86. Stefan Vorkoetter
    April 23, 2010

    It’s true that they are nominally 1.2V instead of 1.5V, but actual 1.5V (alkaline) batteries will quickly drop below 1.2V during use. In actual practice, the 1.5V alkalines won’t power your device for as long as the 1.2V NiMH batteries will. See the graph in my article Choosing and Using NiMH Batteries.

  87. Lloyd
    April 23, 2010

    Stefan, Thanks much for your testing, posting and your prompt reply. My new Eneloops and charger are on order. Take care, Lloyd

  88. Lydie Dominique
    May 11, 2010

    This is an awesome review; just what I needed to know. Puts the 2 types of rechargeables in perspective and will help me make an informed decision. Your testing is what I needed!

  89. rado slovakia
    May 12, 2010

    For all you guys just make u aware the new improved sanyo eneloop is coming – with Rechargeable up to 1500 times

  90. Jodi
    August 15, 2010

    Hi, Great article. I’m new to rechargeable batteries. I’ve heard that it is best to run rechargeable batteries all the way down, and then fully charge them. Is this correct? What is the diminishing factor, say, if I don’t have time to wait for the batteries to charge fully?

  91. Stefan Vorkoetter
    August 16, 2010

    Jodi, it really depends on the charger you’re using. If it’s a “smart charger”, then there’s no need to run the batteries all the way down, since the charger will just charge until the batteries are full, and then shut off. If it’s a dumb charger (charges for a fixed amount of time), then it is best to run them down first, or they will be overcharged. You might want to read my article, Choosing and Using Nickel-Metal-Hydride Rechargeable Batteries at http://www.stefanv.com/electronics/using_nimh.html for more details.

  92. Anne Griffin
    September 28, 2010

    Thanks Stefan. While I glossed over most of the details (just not my thing 😉 ) I’m sure my husband will love this article (and several others) We’ve been using Eneloop in our remotes, pimarly Wii controlers, and kids camera, that seened to eat regular single use batteries and have been very happy. You’ve just given me the confidence to use them in other devices (since there really is low self discarge) and I will be trying them out in a baby toy that sucks batteries (4 C last 2 months or less with daily use of a minimum15 minutes). It was also great to see that Sanyo actually cares enough about their product to contact you with both compliments and more detail/facts.

  93. Dawn
    September 28, 2010

    Hi Stefan,

    Just thought some of your readers might also like to know that they can get Eneloop batteries online at Storks & Berries (www.storksandberries.ca).

  94. Stefan Vorkoetter
    September 29, 2010

    Thanks Dawn. Note that they are quite a bit cheaper at Amazon, but Amazon won’t ship them outside the US, so Storks and Berries would be a good source for Canadian customers.

  95. Evar Simon
    October 05, 2010

    you can get these at NCIX.com for Canadians.

  96. Lee Kok Heng
    October 06, 2010

    Cool product for tree huggers…

  97. Stefan Vorkoetter
    October 06, 2010

    Lee, they’re not just for tree huggers. They’re also good if you don’t want to throw your money away.

  98. Ammar Abotouk
    October 07, 2010

    wow the best review i ever seen although now i own THE NEW Eneloop witch seems to have better Low-Self Discgrage you should try them out

  99. Tia Holley
    October 11, 2010

    Thank you for your report, I just bought some and will try them in my camera as I went through about 40 batteries this summer!

  100. Ray
    October 18, 2010

    Hi Stefan

    Nice reasearch work on the rechargeables – well done. I have been buying the Duracell 2650mAh cells for their high capacity and quality. Although they do not specify them as low self-discharge they seem to hold a charge for 2-3 months at least in my 580EX I and II Canon flash units which power-up more or less within a couple of seconds. I might now try a couple of packs of the Duracell low self-discharge cells. I will now go and clear space in the freezer to make room for them.

    Regards

    Ray

  101. Ian Chen
    October 18, 2010

    Can you tell me about sanyo,Low self-discharge battery Warranty?

  102. Stefan Vorkoetter
    October 19, 2010

    Ian, the warranty is one year, but only if you a Sanyo charger.

  103. Lee Hock Boon
    October 23, 2010

    Anyone out there know where to get eneloop battery at Johor Bahru and the price?

  104. Mel Peterson
    October 29, 2010

    I find that when I use eneloops in my wall clock that the clock runs a little slow. My clock says use AA 1.5v, but the eneloop AAs are 1.2v. Would that cause my clock to run slow?

  105. Stefan Vorkoetter
    October 29, 2010

    Mel, it shouldn’t run slow, since it’s crystal controlled. It should either run, or not. However, if the mechanism is binding, it could sometimes miss a beat, which would make it appear to run slow. Don’t worry about the voltage difference, since a 1/2 used 1.5v battery is only 1.2v as well. We use Eneloops in all our clocks, and they work fine.

  106. Mel Peterson
    October 30, 2010

    Thanks, Stefan. Great article!

  107. Momster
    October 30, 2010

    Thanks for all your work. We have a few 2 y/o PowerEXs that quit charging and are ready to move on. Will try these.

  108. Lloyd Klein
    October 30, 2010

    First let me thank you for taking the time and trouble to make this information available.

    I have been using rechargeable pen-light batteries for photo-flash for over 40 years, since I first bought some GE NiCads. For the most part all have been a disappointment, with the exception of an extra-length pair of Toshiba AAA’s I bought many years ago and still power my cordless headphones, even though the phones call for AA sized cells, they will consistently rin for 5-6 hours on a charge.

    I expected great things from the Sony Cyber-shot 2600 mah Nimh batteries, which came with my camera, but even after full low current discharge and slow recharge, in Sony’s custom charger, they are hard pressed to take more than 20 flash photos; and don’t even think of leaving them in the camera for a week before taking photos. I have had pretty much the same results with Energizer 2500 mah and Panasonic 2050 mah, which came with a fancy LCD display charger. A set of Quest [from ovonics@work] are quite similar except lower capacity – I suspect 1400 mah. Finally my newest set are Kodak 1800 mah and these are by far the weakest, with the fasted shelf drain. I look forward to getting a set of the batteries which you found kept a high average voltage, perhaps my camera wont pronounce them dead so quickly – more important they won’t take forever to recharge the flash. Interestingly even after the camera pronounces them dead, I can use the camera to play back photos on its 3″ screen, with those same “dead” batteries, for over 1 hour.

  109. Pacun Gohan
    October 31, 2010

    This E8GE AA 1000mAH and AAA 800mAH, NiMH Rechargeable 1000 life cycles; sure will kick eneloop right on the ass.

    http://www.e8ge.com/batteries/

    http://www.stefanv.com/electronics/table.cgi?file=low_self_discharge.html&title=Low%20Self-Discharge%20AA%20Battery%20Test%20Results

  110. Stefan Vorkoetter
    October 31, 2010

    Pacun, if you look at what you’ve found, you may notice that one of the sources you found about the E8GE was taken from my own comparative review: http://www.stefanv.com/electronics/low_self_discharge.html

    And if you’d actually looked at the results of mine that you’re quoting, you would have seen that they don’t “kick eneloop right on the ass”. They’re only slightly better than Rayovac’s Hybrid batteries, which were the worst of the bunch.

  111. Manish Sharma
    November 02, 2010

    Very detailed and informative review!

  112. Allan
    November 04, 2010

    That is a really excellent logical,comprehensive and lucid piece of work. Very informative and useful. Thanks a lot.

  113. Petr Antoš
    November 06, 2010

    tip: když akumulátory, tak sanyo eneloop, to není reklama, ale fakt 🙂 obycejný NiMH se vybije sám cca za mesíc (tzn. nemá smysl ho dávat do DO, myší, klávesnic, tam kde je malá spotreba) eneloop se chová jako alkaline (muže být uložený roky) a i tam kde je spotreba velká (fotáky, RC modely …) vydrží vetšinou déle, možná s vyjímkou 2500+ mAH. Eneloop prý dokonce namají ani pametový efekt, což obycejné NiMH rozhodne mají …. byl tu snadný link, tak dávám jak jsem koupil 🙂

  114. Hammerjacks Steve
    November 07, 2010

    Very well written article/review. Thanks for your efforts.

    I am now thinking these will be better than the Duracell counterpart at just a slightly higher price. I take it that you have not run the same testing on the CEF14DX4N by Duracell.

    My digital camera doesn’t last more than 5 minutes with alkaline batteries but used to work fine with NiMH. I am hoping that it will work fine once again with new NiMH batteries

  115. Stefan Vorkoetter
    November 09, 2010

    Steve, I’m not sure exactly which battery the designation CEF14DX4N refers to, but I did do a comparative review of several brands of AA low self-discharge NiMH, including Duracell, here: http://www.stefanv.com/electronics/low_self_discharge.html

    If your camera worked well with regular NiMH, it will work even better with the low self-discharge ones like these Eneloops.

  116. Grant Grieves
    November 11, 2010

    I Really Like the Eneloop Batteries in my camera … lot’s of power to spare after shooting hundreds of pictures.

  117. Camilo Alarcon
    November 20, 2010

    I’ve been using Eneloops in my Pentax K-x and the results so far are phenomenal. I can take an average of 350 to 400 photos with one charge, most with full flash discharge. Excellent choice for digital cameras. I haven’t used them for other applications so far.

  118. Barbara Hobbs
    November 26, 2010

    haven’t read all of this, but I love eneloop batteries. I use them in my digital camera and they stay charged longer and last longer than any other rechargeable batteries I’ve use.

  119. Michael Roberts
    January 10, 2011

    Hey.

    Can somebody advise me on charging my Eneloop batteries please. I have 3 x 1.2v AA batteries in a holder/pack that i need to charge. I have a MW2168 charger but i am unsure of what settings to use. It is an adjustable charger and has 50/80/120/180/240/300 settings but i have lost the manual. They are for use in a cree led headlamp i built for mountain biking. Any help would be gratefully appreciated.

    Cheers.

  120. Stefan Vorkoetter
    January 11, 2011

    Michael, use the 180 setting for 16 hours, assuming the batteries are completely dead. If they weren’t completely dead, leave the light on until they are.

  121. Rose Ann Truster Dickey
    January 24, 2011

    i would like to purchase some of the sanyo eneloop rechargeable batteries, but have been unsuccessful in locating a store that sells them. Anyone know where i can find them?

  122. Stefan Vorkoetter
    January 26, 2011

    Rose Ann, where are you (which country)?

  123. Grant Grieves
    February 10, 2011

    I really love these batteries in everything I’ve used them in … there ready to go when you buy them & don’t need re-charging for a long time … the re-charge lasts & lasts …try ’em you’ll like ’em. Grant in Hendersonville,TN USA

  124. Stefan Vorkoetter
    February 23, 2011

    Jack, I assume you mean the ones that are rechargeable 1500 times according to a comment below? I’m not sure, since I haven’t seen those yet.

  125. Stefan Vorkoetter
    February 24, 2011

    Jack, that’s probably a lithium iron disulfide battery. The nominal voltage under load ranges from 1.4V to 1.6V, but the voltage with no load is about 1.8V, hence sending your battery tester off the scale. See this Wikipedia article for more information on the various lithium-based battery chemistries: http://en.wikipedia.org/wiki/Lithium_battery

  126. Brian Matsumoto
    March 28, 2011

    Thank you for the review. I had switched to the Sanyo Eneloop and encouraged my friends to buy this battery.

  127. Jason Wong
    March 28, 2011

    Just placed an online order with a reseller here in Malaysia. Can’t wait to get them.

    By far, Sanyo is the only that I’ve seen claiming that their batteries can last for 1000/1500 cycles depending on their model. Other brands that I’ve used before never claim their number of cycles, and they were really very short-lived. I just hope that Sanyo eneloop rechargeable batteries do live up to its promise =)

  128. Avinash Lewis
    April 05, 2011

    Hi all, I am heavy user of Sanyo Enloope battries for 4 years in a row, By my exprience(im a chemistry student and a Engineer) Enloopes are the worlds best battries, i use it so heavily that in my NIKON L21 they last 3 days with continuous use and 1800 shots, other battries last 10% of it.

  129. Eileen Westrom Routson Herrick
    April 16, 2011

    I have used Energizer, Duracell and Ray-o-vac rechargeables because I believe in the whole concept of rechargeables, however, I too have been disappointed in there performance. I recently bought some Apple AA batteries for my IMac and I love them! I need to buy some more for other devices but someone told me about the Eneloop. Do you have any experience with the Apple rechargeables? If so, how would you compare them to the Eneloop?

  130. Stefan Vorkoetter
    April 19, 2011

    Eileen, I don’t have any experience with the Apple AAs. However, if they are marketed as low self-discharge, then they are likely one of the brands I’ve reviewed here, since Apple doesn’t make their own batteries.

  131. Martin Gordon
    April 30, 2011

    I’m not into electronics but even so this review has convinced me that Sanyo’s Eneloop batteries are the way forward. I’m off to Amazon to get some! 😉

  132. Andrew Ostrowski
    May 01, 2011

    just both Eneloop charger with 4 batteries($29.95) in Black’s Camera in Calgary, also other packages of batteries are also available, apparently Canadian Superstore also carry them as President Choice Brand for slightly less then original Sony product

  133. Stefan Vorkoetter
    May 01, 2011

    Andrew, you’re right that the President’s Choice are the same batteries. See my comparison of all the major low self-discharge brands (link in the list of articles above).

  134. Lionel Yexley
    May 09, 2011

    PHEW! Complicated but informative. Many reviews also bear out that these are THE batteries to have for large screen digital cameras in particular (like wot I have just bought!)

  135. Vedran Racki
    May 23, 2011

    Excellent review, thanks for the info! How about “new” Sanyo Eneloop XX with 2500MAh, have you tried them out yet?

  136. Stefan Vorkoetter
    May 24, 2011

    Vedran, I’ll be getting some of the XX cells in a few weeks to start testing. Thanks for your interest.

  137. Jesus- Matthew
    June 21, 2011

    There are some incredibly inexpensive rechargeable NiMH AA and AAA batteries for sale on eBay by sellers … and they’re incredibly bad!

    Stefan, I had been wondering if you’ve seen test results, tested or would be willing to test a set and post the results but never mind… I found some info myself and clearly these are horrible batteries – per the consensus at

    http://forums.ebay.com/db2/topic/Reviews-Guides/Bty-Aa-Nimh/1000746676 and 2 ebay reviews with similar info. Most of the stuff I buy on eBay shipped frm HK is great, but I’ll stay away from these.

    I have some Sony NiMH AA’s and I’m going to buy some eneloop AAAs, now that I know they can be charged in a normal NiMH charger like the BCG-34HLD I have. These are on sale on eBay for $19 for 8 of the 1500-cycle 800 mAh AAA ones. I’m about to buy some. Looking forward to your reviews of the eneloop XX and lite versions that are now out, Stefan!

  138. Stefan Vorkoetter
    June 22, 2011

    Careful, as I’ve heard there are a few fake 1500-cycle Eneloops out there too.

  139. Othello Tanjoco
    June 22, 2011

    This is really cool and insightful review.. I learned a lot too.

  140. Shankar Ramadas
    June 27, 2011

    This is great. I happy that a consumer has gone that extra mile to prove a point. I too like this compared to Sony and popular brands.Just be carefu you dont buy fake ones.

  141. Jason
    June 27, 2011

    Hi Stefan, I have 3 year old eneloops that are now reading about ~1800 to 1840 mAh on the Maha-C9000. They certainly haven’t seen strenuous use at all, aside from occasional use in a digital camera and gps. Definitely less than 15 full cycles over that time period. I have done refresh & analyze and ‘break-in’ on the Maha-C9000 and get pretty well the same results.

    Is this typical or unusual re: capacity? Thanks, Jason.

  142. Stefan Vorkoetter
    June 30, 2011

    It really depends on what the discharge current is that the Maha is using to test the cells. At the 1200mA current that I used in my tests, brand new Eneloops only gave 1848mAh. This is not surprising, because batteries are rated at their C/5 discharge rate, so to expect to see 2000-2100mAh from a new Eneloop, one would have to discharge it at only about 400mA. That being said, all batteries degrade with age, so I would not be surprised to see slightly less capacity in 3 year old batteries.

  143. JB
    July 04, 2011

    Ok thanks, that makes sense. I had been using 400mA, or 20% of capacity discharge current for the ‘refresh & analyze’, producing ever so slightly lower results than the ‘break-in’ mode [Charge @ 0.1C for 16 hrs; Pause for 1 hr; Discharge @ 0.2C; Pause for 1 hr; Charge @ 0.1C for 16 hrs].

    It could also be due to lack of ‘exercise’ for the batteries over that time period, or as you said cell degradation. Other people have been reporting near full results even with 5+ yr. old eneloops, but that could be due to how they were used I suppose.

    cheers,Jason.

  144. Asif Istiaque
    July 21, 2011

    i have used sanyo enoloop and uniross hybrio both are well regarding the price . the more suger the more sweet. enoloop does the best . uniross hybrio also stands for competing with other nimh cell.

  145. John Schmidt
    August 19, 2011

    Great review! have you seen/tested the new 2500mAhr Eneloops?

  146. Stefan Vorkoetter
    August 22, 2011

    John, I haven’t tested (or heard of) 2500mAh Eneloops, but I did recently finish tests on the 2nd generation 1500-cycle Eneloops, and will be updating this page soon.

  147. Ian Kingsley
    September 03, 2011

    I have just started using eneloop batteries in my radio transmitter, this should help when going flying at very short notice.

  148. Dan Costalis
    November 14, 2011

    Any idea if the Eneloops of today are the same specs? I’ve had nothing but bad experience with rechargeables, but these seem very promising.

  149. Bryan Joy
    February 17, 2012

    As an RC Airplane pilot I use the hell out of batteries. As an electronics business owner there is so much riding on batteries. I use these ENELOOP 2,000 maH batteries and nothing else in my airplanes. I custom build battery packs for my airplane and for customers too. I have found that these batteries will HOLD a charge for a longer period of time than any other on the market. These batteries are the life blood of my airplanes and I would never trust any other brand. The best charger I have ever found for this type of battery is a SIRIUS CHARGE PRO PLUS manufactured by PEAK ELECTRONICS. The best thing about PEAK ELECTRONICS is thay are a “Mom and Pop” locally owned and operated SMALL business, and all of their SIRIUS CHARGE chargers are proudly MADE IN THE USA! Each charger is HAND BUILT and can be shipped anywhere in the world. Cant say enough about this company. Check them out at SiriusElectronics.com.

  150. Kelvin Koh
    February 25, 2012

    This battery is far better then the traditional NICD or NIMH. I full charge the battery and leave for a month of holiday and the battery almost remain the same capacity.

  151. drbobsolomon
    March 07, 2012

    This is a fine, well-crafted analysis of this battery type. You are to be congratulated on clarity of writing, readability of style, and usefulness of content, reflected in the quality of the thread your original article has generated. Every question I had about Eneloops, and I had many because of my unfamiliarity with that type of battery, has been answered in one place, a rarity online. Well-done.

  152. ed parauka
    March 13, 2012

    Hi, Is it necessary to have a Sanyo charger to recharge the Eneloop batteries? I have a Kodak wall charger, Model K600, that I use to reharge Kodak and other brand batteries. Ed

  153. Stefan Vorkoetter
    March 13, 2012

    Ed, you can use the K600, but it’s an overnight dumb charger, so don’t use it unless the batteries are almost dead.

  154. Vaylies
    March 13, 2012

    Very informing article. Have not used any rechargeables since my game boy advance died.(Oh my thats like a decade ago..) My experience with rechargables are bad and had stayed far away from buying any even though I use up alot of batteries. This acticle leads to some rethinking. Even if not Eneloop technology had gone far from that game boy era. Perhaps its time to try rechargeables again.

  155. ed parauka
    March 13, 2012

    Hi again. Thanks for quick reply. So, what charger would you recommend for the Eneloop, instead of my Kodak 600?

  156. roxanne
    March 21, 2012

    Hi sir, good day. Can i ask you a question? 1 month before i bought 2 pcs of eneloop batteries (i will use in GE digital camera), but i only have energizer battery charger. Is eneloop rechargeable battery and energizer battery charger compatible?

  157. Stefan Vorkoetter
    March 22, 2012

    Roxanne, the Energizer charger will be fine, so long as it is NOT one of those super-fast ones. It should be a charger that takes 2 hours or more.

  158. rica
    April 21, 2012

    can i use samya charger for my eneloop battery?

  159. rica
    April 21, 2012

    sir, i already have eneloop batt (AA) and charger. how long will it take to fully charged my batt? thank you for a repy

  160. fyesilova
    May 11, 2012

    I have received 2007-10 dated aaa batteries and inserted 3 of them into a 3W led flashlight. I have no hobby charger to measure the capacity but It runs the light about 4 hours.

  161. efren bruno
    May 15, 2012

    what an amazing review… at first it made me drip blood from my nose.. then suddenly i got it..

  162. Nick
    May 26, 2012

    You have done a great review. Your graphs and tables are excellent. I don’t have time to read your other work or all of these reviews, but I do have a suggestion. A background in basic calculus is really helpful for the kind of quantitative analysis you’re doing. The reason your extrapolation was too low is that you assumed the discharge amount was a linear function of time. In that case, the rate of discharge would be constant. As Sanyo stated, the rate of discharge decreases with time. Then maybe the charge left can be modeled by an exponential decay function. Anyways, the rate of discharge is called a derivative in calculus. Thanks for the information! I’m going to put mine in the freezer.

  163. Stefan Vorkoetter
    May 26, 2012

    Hi Nick:

    Actually, I did assume that the discharge was exponential. If you look carefully at my first curve, you’ll see that it’s not a straight line. Further tests with these, and other low self-discharge batteries, has confirmed that it is indeed exponential (for example, I predicted within a few percent the remaining charge after 16 months given just the 1 week and 7 week test results).

    Stefan Vorkoetter
    BMath (U of Waterloo, 1987), MMath (1989)

  164. Nick
    May 28, 2012

    Oh, it is exponential! You’re right. The curve in the table under the heading “Self Discharge” is not linear. Sorry about that. Now I’m embarrassed. Tables don’t really do it for me.

    So you are a full-blown mathematician. Hopefully I will be one too in a couple months. Keep up the good work!

    Nick
    BMath (Oregon State, 2009), MMath (in progress)

  165. 5moufl
    June 09, 2012

    Firstly, thanks for the amazing work on this test (and also all the others) Guys like you should be rewarded somehow for doing that. I wish more people would know about this.

    I have one quick question that you might be able to answer: Would it be ok to use this charger to recharge the Eneloop batterie http://matthieu.benoit.free.fr/chargeur_batterie_NiMH_Canon_CB-4AHE.htm
    I think it’s one of those “smart” chargers but I wanted your advice so you could check out the specs.

    Thanks!

  166. Stefan Vorkoetter
    June 09, 2012

    Hi 5moufl. I haven’t been able to find out for sure if the charger is a smart charger, but based on the current ratings, I suspect that it is (a dumb charger wouldn’t charge at such high currents as it would be unsafe). I would however avoid making a habit of using the 1275mA Quick mode. If I’m interpreting things correctly, this is what you get if you put in only two cells, in the two outer positions.

  167. Martín La Rosa
    July 23, 2012

    So the specs of my enloops says charging current x time: 2000ma x 1.1H (fast charging current) http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf
    What does that mean? That I can charge them at 2.2 Amps? I have an ImaxB6 charger that I use for my Helicopter’s LiPo batteries and I intend to use them for the enloops as well.

    How much current should I use? The max charging current should still be safe if it is recommended by the manufacturer right? Do you have any word from Sanyo about that?

    Great article man! Thanks a lot from Argentina.

  168. Stefan Vorkoetter
    July 24, 2012

    Martin, 2000mA x 1.1h means you can charge at 2000mA (2 Amps). Note that this is only safe if you have a smart charger, that does proper delta-V peak detection for NiMH. Does the ImaxB6 charger know how to charge NiMH batteries? Personally, I won’t usually charge my Eneloops at more than 1 Amp (taking just over 2 hours to charge).

  169. Martín La Rosa
    July 24, 2012

    So it means that it will take 1.1 hours at 2 Amps? Then why, if that is the maximum charge recommended by the manufacter, should we avoid it and cut it in half?
    It does LiFe, Lipo, LiOn, NiMH and Ni-Cd. And it has delta peak sensitivity. I’ll check if it has delta peak sensitivity specifically for the NiMh when I get home after work.

    Here is the charger in case someone is interested: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=6478.

  170. Rostamiani
    August 06, 2012

    Hi
    Thanks for your really helpfull review 🙂

    I have a Sony smart charger ,There is a Refresh button to discharge the battery before charging
    Is this necessary for NiMh batteries ? I always do this !

    Thanks a lot

  171. Andreas Mohr
    August 11, 2012

    Hi, it seems veritable (4000/4500mAh) good quality Baby C cells and Mono D cells (LSD) can sometimes be bought as well, e.g. provided by Tronic (currently sold online for EUR 3.99, by Germany LIDL), as favourably described by http://www.geocaching-dessau.de/wp/?p=2717
    (it is said that in Europe eneloop is sold in AA/AAA variants only).
    Not that I need those variants, it’s just that this info was missing here 🙂

  172. Steven
    August 13, 2012

    hi, i’m interested in using eneloop batteries for my device . Can i use it with my energizer charger . It seems that the specifications are same

  173. Cindi
    August 21, 2012

    I was also wondering if these batteries could be used in a cordless phone. Would the phone charger work to charge them OK? I have a PanasonicKX-TGA542 if that matters. They currently have Panosonic MI-MH AAA batteries in them.

  174. Corey
    August 26, 2012

    I was wondering if you do not use all the batteries and use only 4 AA batteries and save 4 AA batteries of an 8 pack, would the 4 AA batteries saved wear out at the same rate as the batteries that were being used. Another rechargeable battery competitor stated that their batteries will wear out after about 4-5 years whether they are used or not. This would indicate that it is better not to buy more batteries than could be reasonably used. Also, can you really get 1500 times recharging with these batteries? and what causes the batteries to have a less than optimum charging amount times? I have a GPS unit that has a large viewing screen and eats batteryies. Thank you.

  175. Koos Kok
    September 01, 2012

    Everything I wanted to know after hearing about this new type of battery and more! Thank you very much for sharing this information.

  176. Maria Belen
    September 20, 2012

    Hello..so interested with the Eneloops batteries.. I just bought with me a Sanyo Blu Charger with 2AA Sanyo batteries just to try Sanyo batteries.I needed the batteries for my digital camera. I had used many products,Energizer, Sony, CDR King, and many others to mention…I just would like to ak if the items I bought a while ago is a wise buy for me?
    Thanks. God bless.Hope to hear your comments soon.

  177. KOS
    September 20, 2012

    Very nice review. Practical tests from individuals are very important, as each company promotes their pruducts to be the best.

  178. Subbu
    September 29, 2012

    I am an electricla engineer but had not know these facts about Ni-MH cells before. I will return the NiMH I bought for my camera flash. No point keeping two sets if these cannto retain charge for long. Would go in for Eneloops

  179. Anne Radney
    October 23, 2012

    I did not know anything about these batteries until about a week ago when I checked reviews of a new AA-battery powered camera I intended to buy. I appreciate this very thorough review, and will definitely buy these batteries.
    I used to buy Energizers, they do not old a charge at all. I just charged 4 AAs last week, checked them today and they are absolutely dead! They are sitting in the charger all day and still chargiing. That is ridiculous.
    I hope I will not be disappointed with the eneloops.
    Thank you for the fantastic review! I wished more people would know about these batteries and more stores would sell them. So far I haven’t found a retailer who sells them in the store, everything is online only. I still prefer to buy certain things in a store. Old fashioned? Maybe!

  180. Henry Mills
    November 28, 2012

    Hi Anne Radney, I feel your pain. There’s only two retail chains I know of in my neck of the woods (Ontario-Canada) that carry Eneloops. Computer chain store called Canada Computers. As well as Costco.

    There’s also Shopper’s Drug Mart that carries Duracell pre-charged (white top, made in Japan) that is well thought by many, to be repackaged Eneloops in a Duracell wrapper.

    Good luck, I know that probably doesn’t help you but I’m sure you’ll find at least one store wherever you’re from that carries them.

    I do have personal ordering experience from Thomasdistributing.com. I’ve ordered 3x from them and the delivery was prompt and accurate. If you’re buying in bulk, the shipping charge may be worthwhile.
    I know you’re weary of online orders, but there you go. So was I up until just 4-5 years ago. It’s not as bad as it seems. Good luck.

  181. Rusty
    March 11, 2013

    Thank you for the research. There is an area that I feel needs covering; durability. I have read that these batteries are not suited for environment with vibration and should not be used in radio control aircraft due to this.

    “These ultra high capacity (and very high impedance) cells are indeed unique and delicate.. and that’s why you’ll never see us offer the Sanyo Eneloop or 2700 AA NiMH cell assembled as a receiver pack since they just can’t handle high servo current loads, high temps and high vibration associated with using them on board an aircraft.”

    http://www.hangtimes.com/rcbattery_faq.html

    What are your thoughts on doing some additional research in this area?

  182. Dyse
    March 29, 2013

    Hi guys,

    recently i bought one canon SX 150 camera, its awesome picture clarity dragged me to purchase it. I am happy with that one , but having the battery problem, as the given alkaline batteries are damn shit. so can you advise the best battery for my canon SX 150

  183. Barb
    April 11, 2013

    Thanks for the research. Great information. Any ideas about how long the batteries will last in outdoor solar cell lights. The temperatures will obviously fluctuate during the year. Also, I’m thinking the recharge cycle from the sun will definitely lower the power retention. I’ve found that they last about year under these conditions.

  184. Oddie
    May 27, 2013

    Hey there. Some quick comments.

    In my experience Sanyo Eneloops are very product dependent. Generally speaking the LSD technology serves a purpose. However, I have noticed incompatibility and/or underperformance in certain situations. To the degree that I have moved to alkalines or will be seeking traditional NiMh to replace the Eneloops.

    Case 1: Canon S2IS digital camera requiring 4xAA. I’m no battery engineer but i’ve noticed that while fresh charged Eneloops work right away, if you leave the camera idle for awhile the batteries fail to fire up the camera the next time. I get a “change batteries” message. If I take the Eneloops out, stick them into flashlight for a moment (on) and then return them into the camera then it works again. Something about internal resistance? Or Voltage sagging and “waking” up?

    Case 2: I have some Sennheiser RS160 wireless headphones. I try using Eneloops AAA in the headphone portion. I’ve been finding that they have great difficulty firing up the ‘phones … they do not connect or turn on. I am currently using alkalines (which work great but of course are not rechargeable)

    So, there are some serious real world issues regarding Eneloops. I like the concept and for the most part they work great … but it would seem that some consumer products require more working nominal voltage (that you can get from alkalines or perhaps “regular” NiMh) than that are offered by LSD batteries.

    Just a thought.

  185. Stefan Vorkoetter
    May 27, 2013

    Thanks for your comments Oddie.

    I haven’t run into any problems like the ones you’ve described, but I believe there are a small number of products for which they may not work well (but regular NiMH will work even less well in those applications). For what it’s worth, I have a Canon SX20IS which also uses 4xAA, and I often have the same set of Eneloops in there for months, and they always work until they are actually depleted (typically several hundred photos and a couple of hours of video).

    And just as an example that is exactly the opposite of your case 2, I have an Apple Mighty Mouse (that I use with my Windows laptop when travelling), that is uses 2xAA wired in parallel. This is presumably to allow for short high-current surges that alkalines can’t provide. To save weight, I run this mouse on a _single_ Eneloop, and easily get a month of use out of it that way.

  186. John Baum
    June 13, 2013

    I am trying to understand why the proprietary, soldered together in series, NiMH battery packs used in cordless telephones have useful lives of no more than 1-2 years. Either they use poorly designed and constructed cells or perhaps their charging technology destroys the batteries because of poor circuit design. By design, the cells are always on the charger if the phone is put away in its base.

    Has anyone tried soldering together three Eneloop AAA cells in series for use in a cordless telephone? See:

    http://www.robotroom.com/Soldering-Batteries-1.html

    and

    http://www.robotroom.com/Soldering-Batteries-2.html

    Thanks,

    John

  187. Stefan Vorkoetter
    June 13, 2013

    The problem is both of the things you mentioned. They often use cheap cells, and the phone base station charges continuously at a fairly high current, typically the C/10 “overnight” current, which delivers a full charge in about 15 hours. That’s fast enough to top the battery back up between uses, and slow enough not to damage the batteries TOO quickly. But it will ruin them in a couple of years. And it will ruin Eneloops too, although maybe not quite as quickly as cheap cells.

    There’s really no benefit to using Eneloops in an application like this, because the batteries are always either being charged, or being used. There is no idle time. Even when you’re not talking on the phone, it is consuming power waiting for the base station to connect a call.

  188. gigi
    August 29, 2013

    I’m sorry if this seems like a naive question, however I can’t find an answer.
    I have a 4 slot eneloop charger & charged 3 AA batteries until the charger light stopped blinking. I mentioned to my son that I noticed the last charge didn’t last very long. He said I could only charge 2 or 4 but not 3 batteries & proved it using some volt meter thing. Sure enough 2 of the 3 batteries was fully charged, the 3rd was dead. He said “told you so..” & walked away. He is 10.
    So can I charge the bad battery with a good one? How can I charge 3 batteries in the future without doing two complete cycles? I hope this makes sense!

  189. Stefan Vorkoetter
    August 29, 2013

    Gigi, this kind of charger actually quite annoys me. Basically, it’s not possible to use it to charge an odd number of batteries. If you first charge two, and then insert one of those with the remaining one, it will either not work, or it will overcharge the one that’s already charged.

    The only way around this without buying a more sophisticated (and thus expensive) charger is to have two sets of batteries (six in your case if you have a device that uses three). When your first set is dead, set them aside. When the second set is dead, you have an even number of batteries to charge.

  190. Gigi
    September 01, 2013

    Thank you for the explanation. Makes sense about buying a few more batteries to have an even number to charge.. didn’t even think of that! Where/what brand is the charger that can charge an odd number of batteries? The money I’ve saved in using the Eneloops would make it an investment.

  191. Stefan Vorkoetter
    September 02, 2013

    Very few chargers can still do this. Sanyo’s older models charged individually, but their recent ones all seem to charge in pairs. Sony makes one, http://www.amazon.com/dp/B003GS6FIE which comes with two “lite” batteries (only half the capacity of other Eneloop style batteries, and thus can’t be used together with them). Or, you could buy a slight more sophisticated charger/analyzer like the Maha Powerex MH-C9000 or La Crosse BC1000, as those definitely work on each battery individually (and can do a whole lot more than just charging), but they’re in the $50+ price range.

  192. gigi
    October 02, 2013

    Thank you for the feedback & it sounds like buying more batteries is the better option for us at this time. Appreciate all your input and expertise… I wish you could review all the items I have to make decisions on. You saved me so much time & love your site.

  193. Ivo Kostić
    November 06, 2014

    it’s now about 7 years since your initial tests, how are those batteries holding?

    what percentage of their capacity can they offer today?

    afaik biggest problem i see with nimh and nicd batteries is when one of them dies, and then you have a unbalanced pack that you need to sync with one new battery…heh…

  194. DPaauw
    November 23, 2014

    Is the delta-V full charge detection more reliable with lower or higher charge currents? Or does it matter at all? And do some batteries/chargers work better than others? I know from experience that some chargers will do better than others, having bought a counterfeit IMAX B6AC on eBay that’s a disaster. There are several websites showing how to fix it by replacing surface mount components with high precision ones, so they sold a lot of them.
    I’d guess that most batteries would behave in similar ways. Have you seen any difference in chargers? And my original question: is high or low current charging more reliable?

  195. Stefan Vorkoetter
    November 24, 2014

    The delta-V is caused by a sudden decrease in the internal resistance of the cells when they reach full charge. This decrease means a lower difference between the cells’ internal voltage and the voltage seen externally (the difference being equal to the internal resistance multiplied by the charging current). So, with lower charging currents, that difference is already smaller, and the delta-V will be proportionally smaller as well, making it harder to detect accurately.

    The reason some chargers are better at delta-V detection than others is that it’s hard to do right. There are always small fluctuations in voltage during charging, and a naive delta-V detector would be triggered early by these. One fix is too use a more sophisticated algorithm involving data smoothing, whereas an easier “fix” is to just look for a larger delta-V. The latter results in overcharging, and in some cases, failure to stop charging because the delta-V never gets big enough. At high currents, this can cause serious damage (such as cell venting).

    So, to answer your question, high-current delta-V detection is more reliable, but the cost of failure is also higher.

    I didn’t realize there were actually counterfeit versions of commercially available chargers. I guess that shouldn’t surprise me, since there are counterfeit versions of pretty much everything. I mostly build my own chargers, so I haven’t encountered this aspect of the market.

  196. John
    February 23, 2015

    Now 2015 and this post still going! Thank you for the reviews. How is the original test batteries going?

  197. Stefan Vorkoetter
    February 23, 2015

    They’re still in my regular rotation of batteries. I’ll have to find them and retest them to know he they’re doing, but so far none of the low self-discharge NiMH I’ve tested over the years have deteriorated to the point where I’ve noticed a problem.

  198. tt
    July 17, 2015

    Sadly, I am stuck with the slow Rayovac rechargeable alkaline charger for these, which get them warmer than I like. My main problem is with AAAs. Don’t even think of putting any of them on the 15-30 minute chargers. I found out the hard way when I had put the empty white Eneloops into the Ultalast 30 minute charger. About halfway through the charge cycle, I heard hissing. Dang! At least my Rayovac charger didn’t do that. You can use the Eneloop black Pros on the Ultralast charger, but they have to be empty before putting them into that charger, and they would still leak if put into that charger while having too nuch charge in them. The best result for me has been charging the AAA Eneloop Pros on the Maha C808Mwhen very low off the device. If you forget, you have to run the device using AAAs so that they will terminate on that Maha properly. There are a number of chargers that have difficulty detecting the end of charge signal for some reason. Maybe 700MAH for a AAA may still be slightly too low? (I found that the Eneloop leak if the voltage reaches too high. For some reason, the voltage seems to climb too high if the charge rate is too fast, or too long.)

  199. tt
    July 17, 2015

    (Correction)700MAH charge current from a charger, not battery capacity is what I was referring to. It looks like AAAs needed a 850-1000MAH charge current for reliable termination. Caution: Even some of the most expensive smart chargers can miss charge termination even for AAs, if you don’t run them down first.

  200. Stefan Vorkoetter
    July 17, 2015

    I’ll respond to both of your comments in one reply.

    First, current is measured in mA, not mAh. The latter is a measure of capacity.

    You’re right that to easily detect the voltage peak, the charge current needs to be reasonably high, generally on the order of C/2 or better (C means a current equal to the capacity, so C/2 for a 2000mAh cell is 1000mA). However, it’s perfectly possible to build a peak-detecting charger that works at much lower charge rates. My BattMan II charger can reliably do proper charge termination even at a C/5 rate (e.g. 400mA for 2000mAh cells).

    On the other hand, AAA and to a lesser extent AA cells cannot tolerate repeated recharges at rates much more than the 1C rate (e.g. 2000mA for 2000mAh cells). This rules out any charger that charges in under an hour. It’s simply not good for the cells no matter how good the charger is. The internal resistance of the cells, coupled with the fact that NiMH charging is exothermic, means the cells will get hot. Charging at faster than 1C rate is really only tolerated well by low-resistance NiCd cells, because the lower resistance means less heat, and NiCd charging is endothermic (at rates around 1C to 2C, most NiCd cells are actually cooled by the charging process).

    Regarding cells venting, it’s not the too high voltage that’s the problem. It’s the overheating. In fact the latter causes the former. The measured voltage can only get as high as the cell chemistry allows, plus the voltage drop across the internal resistance of the cell. When the cell gets hot, the internal resistance goes up, so a higher voltage will be seen at the terminals (while the charger is still applying current). Once they vent, the resistance increases even more, so the measured voltage will be even higher.

    Finally, never ever use a rechargeable alkaline charger for NiMH cells. The charge termination detection for those is not compatible with NiMH.

  201. Mike
    September 22, 2015

    Firstly, thank you for all the information/advice regarding charging, battery’s different technologies etc. I have tried to gain a better insight into how best to look after my battery packs I use for flying, but I’m still in the dark without a torch unfortunately. I have a 8 pack of Sanyo eneloop 9.6V 2000mAh batteries. On the back is a label that says charge at 200mAh for 14-16 hours. I’m using an Ansman xbase 2.0 deluxe charger to charge these packs.I am currently charging these at 0.2A which I’m assuming equates to the 200mAh. What would be a suitable fast charge rate for these packs, and why do the manufacturer state “charge at 200mAh for 14-16 hours” if they can be rapid charged as well. I apologize for my ignorance in all this battery charging stuff, but this appears to be a science in its own right, and not just plug it in to a charger a wait for it to charge.

    Thanks

    Mike

  202. Mike
    September 22, 2015

    Just a quick side note, I’m not in any real hurry to charge my batteries, and by that I mean Im OK with them taking 12+ hours to charge, But if they can be charged faster without having any damaging effect then so much the better.

    Thanks

    Mike

  203. Stefan Vorkoetter
    September 22, 2015

    That charge rate is the so-called “dumb charging” rate. The battery can safely be charged at that rate without needing any charge termination method other than, “remember to stop charging after about 15 hours”. If you forget to remove them and leave them for an extra few hours occasionally, no harm will be done.

    Charging at much higher rates is possible, but as the rate goes up, it becomes more an more important to terminate the charging as soon as the battery is fully charged. Once charged, all the current flowing into the battery is converted into heat, at a rate proportional to the square of the current (I2R). At low charge rates, the battery can shed that heat fast enough to not get too warm. At higher rates, the battery will get too hot and become damaged.

    Batteries like Eneloops (and pretty much all AA cells) have a relatively high internal resistance, and thus will get a little warm even before being fully charged. Therefore, even with a smart charger that stops immediately after the battery is full, it’s not a good idea to charge at more than the C/2 rate (1000mA or 1A for 2000mAh cells). This will take about 2 hours. Larger cells, like SubC size, often have lower internal resistance, and can be charged at C or even 2C rates (1 hour and 1/2 hour respectively). Back in the old days, NiCds could be charged at even higher rates, because their charging reaction is endothermic (i.e. they cool while being charged). I used to charge SubC-sized 2400mAh NiCd cells at 4C, which takes about 15 minutes. I even built a charger once that would control charge rate based on temperature, starting with a 10C charge rate. That was high enough that the endothermic reaction wasn’t enough to absorb the heat, so the charger automatically tapered the rate as the temperature went up. Typical charging time was about 10 minutes.

  204. Mike
    September 23, 2015

    Thanks for that, I’ve changed the charge rate from 0.2A to 1A and it charged in about 1hour 40, they got slightly warm, but the charger switched off automatically at the end. Thanks again…a very interesting discussion.

    Cheers

    Mike

  205. Krish Rao
    April 10, 2016

    Does anyone know, what is the minimum charge current acceptable with Eneloop batteries? or to put it in another way, Is it possible to charge (accumulate ) a few micro Ampere current over long periods of time efficiently?

  206. dhoni
    April 10, 2016

    Hi, i hope this thread still alive..
    im buying 20+ pcs on mid 2015, but i kinda disappointed on this item. On the box it says capable on 1500 charging cycle. But in reality the battery is kinda dead after 10x charging. for example, when opened from box 1 AA battery can be used on my wireless mouse abut 3 weeks. but now it only survive 1 days.. is there any way to fix this?
    fyi im using 12h original panasonic eneloop charger.

  207. Stefan Vorkoetter
    April 11, 2016

    The self-discharge rate is about 40 microAmpere, so you’re going to need at least that much charge current to even maintain the state of charge.

  208. Stefan Vorkoetter
    April 11, 2016

    Perhaps you received counterfeit cells? Was the price too good to be true? I have Eneloops from 2007 that are still working great.

  209. Andre Balogh
    July 03, 2016

    Stefan,quite impressed with all your knowledge, test and information provided here regarding eneloop cells, been using them for over 4-5 years.
    Have worked with rechargeable batteries for quite a few years, reading This website thorougly gave me much more information than I ever dream of.
    Regarding your battery tester that you designed and place very good instruction for it duplication , you mentioned that it is able to measure cell internal impedance, you do not indicate which method, can you please give us more details , does it use ac impedance or Delta V over 2 different currents .if Delta V what currents and how long before the measurements are made .
    Are you familiar with HP 4328A Milliohmmeter ?, if so what is your opinion to use it for determining cell impedance ?
    Thank you in advance for what ever reply you care to give back .
    Blessings to you and your loved ones. Andre Balogh

  210. Chor Win
    August 08, 2016

    Thank for the sharing and good info on Eneloop batteries’ testing.
    Appreciate it and good reading on your post.

  211. tt
    October 25, 2018

    Thank you guys all for your informative posts. By the way, you mentioned that an alkaline charger should not be used with NIMH. You are right. However, this alkaline charger came from the Rayovac line of Renewal chargers. The original gray one did not do NIMH. Then Rayovac came with two versions of a more modern charger, the older rectangular brick that they said was for NIMH, but still cooked them, and the newer one I have before they discontinued it. Rayovac then made their line of dumb NIMH charger in the same form factor that did not do Renewal. Rayovac made their line of chargers that were supposed to work with NIMH and rechargeable alkaline, just before they pulled them off the market. The chargers they made tended to overcharge NIMH as the charging current was too low for the negative delta V signal to be easily seen. I long since gave up on the charger, maybe it was good for their line of low capacity NIMH AAA which were not very good for other chargers. (600MAH capacity)

  212. tt
    October 26, 2018

    I found out that Eneloop AAA work best by using a Nuon charger, and running them through the refresh cycle each time you put them in to charge. Using the Duracell Ion speed 8000 causes too much pressure buildup in them and also causes them to vent, even while not hot, and dries out their electrolyte. Eneloop AAA don’t tolerate anything faster than an hour, you guys are so right. It works OK for the X2Power 1200 MAH AAA cells, they don’t get high pressure and vent on that charger. The trouble with the Duracell ION 8000 is this: It charges at a 4C rate for a fixed 15 minutes when red lights are on, then flashing green lights after the 15 minutes, until they all turn solid. The solution was to use a voltage measurement circuitry, and turn off the high speed charge when the batteries reached 1.2 volt. That was about the only thing that could deal with preventing the pressure from getting too high. I found that the batteries don’t always have to get hot for the venting to happen. My guess is that smaller cells cannot usually take even a partial charge at high rates past the 1.2 volt mark, especially anything lower than about 1000-1200 MAH capacity. I have also found missed charge terminations happening in this charger at the second stage of charging. I have found why most batteries don’t survive long in these chargers. The fast speed dries out the electrolyte and the internal resistance gets to the point where the charger will not charge them. I will be sticking to the more humble chargers, not the ones that charge in pairs!

  213. Stefan Vorkoetter
    October 28, 2018

    Charging at really high rates is really only suitable for NiCd cells. The NiMH charging reaction is exothermic (generates heat), and the higher the charge rate, the more heat is generated (in addition to the heat generated due to internal resistance). The NiCd charging reaction on the other hand is endothermic (absorbs heat; i.e., “generates” cold), so higher rates actually result in more cooling to compensate for some of the heat generated due to internal resistance.

  214. Aaron Linsdau
    August 28, 2019

    I did a video review of the Eneloop batteries where I talk about my 10 years of experience using these rechargeable batteries:
    https://youtu.be/SdTMEEuL56o

  215. Stefan Vorkoetter
    August 28, 2019

    Nice review! I still have the original Eneloops I bought in 2007, and they still work great! Some time when I get a chance, I’ll round them up and retest them. BTW, Eneloops are no longer a Sanyo product. Panasonic bought the tech and the name from Sanyo quite a while ago now.

  216. tt
    September 23, 2020

    I have recently retired my Nuon charger. It looks like most chargers that do only 4 at a time don’t usually come with the sophisticated level of smarts needed to avoid damaging the batteries. I found NIMH to be very sensitive to overcharging. I could not figure out what was ruining my batteries for almost all these years, it turned out that the Nuon charger was overcharging them. It was sold as a 1 hour charger. It looks like this charger looks for a minus delta of 20 millivolts, which is more suited to Ni-cad. The charger would typically time out. The Nuon AAAs did not tolerate the slight overcharge and the X2 power 1200MAH ones wouldn’t fill up. I finally found a MH800S charger online and bought it. I was able to save some of my Eneloops, but the charger came too late to save all of them. As for those 15 minute chargers, they are very picky about what batteries they will charge, as they are very sensitive to internal resistance. It does not help that NIMH have higher internal resistance to start with, maybe that’s why they did not make their way very well to power drill packs?

  217. CS
    January 23, 2024

    A search on the Eneloops led me to your article.
    I’m capacity testing some old Ni-MH and was pleasingly surprised that they were still holding 1500mAh. I don’t know how old they are – the first gen HR-3UTG along with Sanyo branding suggests possibly 15 years and they were in storage, unused since late 2016 as I relocated and settled between different countries and only now I’m able to re-organize my stock

    It certainly shows how much longevity they can achieve! Maybe after a few cycles capacity will go up a bit too.

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