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

February 22, 2009

Last updated January 10, 2012

Three popular brands of pre-charged (low self-discharge) rechargeable NiMH AA batteries.

Three popular brands of pre-charged (low self-discharge) rechargeable NiMH AA batteries.

It was early in 2007 when I first published my review of Sanyo’s Eneloop low self-discharge rechargeable batteries. Since that time, other manufacturers have jumped on the bandwagon, and comparable batteries are now available under many different brand names. This review compares the performance of several of these batteries (including Sanyo’s).

What Is “Low Self-Discharge”?

Sanyo first introduced low self-discharge technology in 2006 in response to a shortcoming of normal NiMH rechargeable batteries, namely that they suffer from a very high self-discharge rate. In plain English, this means that the battery will run down in a matter of weeks or months even when it’s just sitting there in the package or a switched-off device. This characteristic restricted NiMH batteries to applications where high currents are needed for a relatively short period of time, such as digital cameras.

With the introduction of the Sanyo’s Eneloop battery, NiMH batteries could be used in devices that were traditionally restricted to disposable alkaline batteries, such as wall clocks and TV remote controls. And, when used in gadgets like digital cameras or flashlights, they can be left installed for weeks or months on end and will still work when you pick up the camera for that spontaneous snapshot or reach for the flashlight during a power failure.

A happy side-effect of low-self discharge is that the manufacturer can pre-charge the batteries before they leave the factory and they will still be charged when you buy them many months later. This is great, but in my opinion, the battery manufacturers’ marketing departments over-emphasize this on the packaging (marking them “pre-charged” or “ready-to-use”) while glossing over the underlying low self-discharge characteristics that make these batteries pre-chargeable, and more importantly, so much more useful than ordinary rechargeables.

Comparison Methodology

This review compares the tested batteries in four different scenarios:

  • Fresh out of the package.
  • Immediately after being recharged.
  • One week after being recharged.
  • Seven weeks after being recharged.

In each scenario, we’ll look at the total capacity provided in milliAmp-hours (mAh), total energy provided in milliWatt-hours (mWh), and average voltage under load (V). In the one-week and seven-week tests, we’ll also look at the charge retention (remaining capacity as a percentage of just-recharged capacity). The brands being compared are (in alphabetical order):

  • Duracell Rechargeable Pre-charged
  • E8GE 1000 Ready to Use Rechargeable
  • EasyPix Pre-charged Rechargeable
  • Energizer Recharge
  • Panasonic R2 Technology Rechargeable
  • Powerex Imedion
  • President’s Choice (P.C.) Rechargeable
  • Rayovac Hybrid
  • Sanyo Eneloop
  • Sanyo Eneloop 2nd Generation
  • Sanyo XX
  • Sony CycleEnergy
  • Tenergy Centura

As I get my hands on other brands, I will test those too and update this article with the new information. (If you are a manufacturer or distributor of low self-discharge AA batteries and want to see yours in this review, please contact me to arrange to have them tested.)

All the tests were done using my BattMan II Computer Controlled Battery Manager. Discharging was done at 1200mA, which is on the high end of what these batteries would be expected to deliver in an application such as a digital camera. Charging was also done at 1200mA, using the −ΔV peak-detection method. The charging graphs were inspected manually to ensure no false peaks occured. The initial recharge (after the fresh-out-of-the-package test) was repeated until the capacity stopped increasing.

The Results

The table below contains all the results for the batteries I’ve tested so far. The batteries were tested in groups of four cells, but the results are for an individual cell (i.e. one AA “battery”). Additional comments appear after the table.

  Dura-
cell5		 E8GE Easy
Pix		 Ener-
gizer		 Pana-
sonic		 Power-
ex		 P.C. Rayo-
vac		 Sanyo
1st Gen4		 Sanyo
2nd Gen		 Sanyo
XX		 Sony Ten-
ergy
Date
tested		 Feb’09 Feb’10 Aug’09 Jan’11 Aug’09 May’09 May’09 Feb’09 Aug’09 Aug’11 Nov’11 Feb’09 Nov’10
Made in… Japan China China Japan China Taiwan Japan China Japan Japan Japan Japan China
Rated
(mAh)		 2000 2000 2000 2300 2000 2000 2000 2000 2000 2000 2500 2000 2000
Fresh Out of the Package1
Capacity2
(mAh)		 1383 1708 1443 259 682 1573 1387 1489 1439 1333 1170 1377 838
Energy
(mWh)		 1509 1818 1565 275 719 1697 1502 1557 1588 1458 1262 1500 903
Voltage3
(V)		 1.09 1.06 1.08 1.06 1.05 1.08 1.08 1.05 1.10 1.09 1.08 1.09 1.08
Immediately after Recharging
Capacity
(mAh)		 1888 1967 2019 2171 1781 2014 1871 1962 1928 1893 2374 1874 1950
Energy
(mWh)		 2181 2183 2268 2496 2037 2240 2131 2216 2217 2144 2711 2167 2205
Voltage
(V)		 1.15 1.11 1.12 1.15 1.14 1.11 1.14 1.13 1.15 1.13 1.14 1.16 1.13
One Week after Recharging
Capacity
(mAh)		 1770 1807 1880 1984 1667 1881 1771 1772 1796 1745 2168 1757 1787
Retention
(%)		 93.8 91.8 93.1 91.4 93.6 93.4 94.7 90.3 93.2 92.2 91.4 93.8 91.7
Energy
(mWh)		 1946 1973 2071 2217 1795 2056 1949 1905 1979 1925 2429 1964 1979
Voltage
(V)		 1.10 1.09 1.10 1.12 1.08 1.09 1.10 1.08 1.10 1.10 1.12 1.12 1.11
Seven Weeks after Recharging
Capacity
(mAh)		 1729 1714 1780 1859 1581 1803 1718 1677 1763 1694 2035 1711 1727
Retention
(%)		 91.6 87.1 88.2 85.6 88.8 89.5 91.8 85.5 91.4 89.5 85.7 91.3 88.6
Energy
(mWh)		 1871 1846 1922 2020 1686 1931 1891 1780 1943 1898 2199 1876 1847
Voltage
(V)		 1.08 1.08 1.08 1.09 1.07 1.07 1.10 1.06 1.10 1.12 1.08 1.10 1.07
Long Term Predictions6
6 Months
(mAh)		 1590 1419 1464 1472 1308 1549 1541 1377 1572 1522 1623 1556 1529
12 Months
(mAh)		 1457 1165 1194 1154 1074 1323 1376 1121 1410 1361 1282 1410 1346

Notes

  1. Out-of-the-box capacity is provided for interest’s sake only. It is not a very useful measure because it really depends on how long the batteries sat on the shelf before you bought them, and the conditions under which they were shipped and stored. In particular, Energizer does not claim that their Recharge low self-discharge batteries are pre-charged, so the low out-of-the-box capacity is not surprising.

  2. The capacity was measured at a 1200mA discharge rate, which is about three times the current at which the manufacturers measure the capacity. As a result, all of these batteries test lower than the advertised capacity. However, the results are more realistic for high-current applications like digital cameras.

  3. This is the average voltage that the battery provided during a full discharge at 1200mA. This is not the same voltage you would see if you just measured it with a multimeter, but it is typical of the instantaneous voltage a digital camera might see while snapping a picture.

  4. The results reported in this chart for Sanyo’s Eneloop batteries are not identical to those in my original 2007 Eneloop review because I have tested a new set for this comparison, using the same new BattMan II battery analyzer that all the other brands were tested with. The differences are due to the normal variation among batteries of the same brand, and differences in the equipment used.

  5. The Duracell Rechargeable Pre-charged batteries that I tested were the ones with a white ring around the positive terminal. Since then, Duracell has switched to batteries made in China. These can be distinguished by a black ring around the positive terminal. I have not tested those, but reports from others suggest that their performance is more like that of the Rayovac Hybrid batteries.

  6. The predicted capacities after 6 and 12 months were derived by fitting the 1-week and 7-week capacities to an exponential curve, and then computing the value of that curve at the points corresponding to 6 and 12 months after recharge. Please note these are only predictions!

Analysis

Charging

All of these low self-discharge batteries can be charged in any good quality AA NiMH battery charger. I would not recommend any charger that advertises a charge time of one hour or less, nor would I suggest using a “dumb” overnight charger. These batteries can also be purchsed with an appropriate charger included. For more information on charging, please refer to my article, Choosing and Using NiMH Rechargeable Batteries.

As mentioned in the notes above, the out-of-the-package capacity is really not a very meaningful measure because it depends on too many things besides the battery itself. However, for what it’s worth, the E8GE battery had the highest pre-charged capacity and the Energizer Recharge had the lowest, delivering only 11% of the rated capacity. However, in fairness to Energizer, they do not claim to be pre-charged, only low self-discharge.

The Rayovac Hybrid batteries and the Panasonics had the lowest voltage under load, at only 1.05V, meaning that some digital cameras might consider them “dead” fresh out of the package.

One Very Long Term Test

Although I hadn’t planned to perform tests for storage periods longer than seven weeks, I recently discovered my pack of Powerex Imedion AA cells, which I hadn’t used since I completed the 7-week test on them 16 months earlier. Out of curiosity, I decided to see how much capacity they retained. Here are the results:

Capacity
(mAh)		 1128
Retention
(%)		 56.0
Energy
(mWh)		 1138
Voltage
(V)		 1.01

Other than the rather low average voltage, 56% capacity retention after 16 months of storage is impressive. Assuming exponential capacity loss, that translates into 80% after six months or 65% after one year.

Immediately after recharging, the batteries with the highest capacity were the Sanyo XX (which has a higher claimed capacity than all the others), followed by the Energizer Recharge (also higher rated than all the others except XX), and then the EasyPix and Powerex offerings, although all the brands provided an acceptable capacity. The lowest voltage, only 1.11V, was provided by the Powerex and E8GE batteries, with the highest coming from the the Sony CycleEnergy brand, followed closely by Sanyo’s first generation Eneloop, Duracell’s Rechargeable Pre-charged, and Energizer’s Recharge.

A week after recharging, things evened out somewhat, with all the capacities falling into a fairly narrow range, with the exception of Sanyo’s new XX with about 20% higher capacity than the rest, and the Energizer Recharge at about 10% higher than the rest.

Those batteries that exhibited the highest freshly-charged capacity (relative to their claimed capacity) generally dropped the most, the most significant example being the Rayovacs, which retained only 90.3% of their capacity. The President’s Choice Rechargeables on the other hand retained 94.7%. The range of voltages was also quite narrow, with a low of 1.08V for the Panasonic and Rayovac models and a high of 1.12V for Sony. Sanyo’s XX retained 2168mAh, which was the highest absolute capacity after one week, but the second lowest as a percentage at 91.4%, a figure is shares with Energizer’s Recharge. Only the Rayovacs had a lower retention percentage, at 90.3%.

After seven weeks, the performance started to spread out again. In terms of absolute capacity, the winner by quite a margin was Sanyo’s new XX, retaining a capacity of 2035mAh. The runner up was once again Energizer, with 1859mAh remaining. Interestingly, both of these, together with the Rayovacs, had almost the same retention when measured as a percentage (85.7%, 85.6%, and 85.5% respectively).

The range of voltages also spread out after seven weeks, with a very low 1.06V from the Rayovacs and a quite high 1.12V from the second generation Eneloops (this was higher than the one-week voltage, but the results were reproduced with two separate 4-packs). Voltage under load can be critical in devices which show a low-battery warning at 1.1V and consider a battery to be “dead” when it drops down to 1.0V. The higher voltage brands will far outlast the others in those applications.

Physically, the Duracell, Energizer, Sanyo, Sony, and President’s Choice batteries look identical (ignoring the artwork on the sleeve of course). They are also all made in Japan. The Rayovac and Panasonic batteries (from China) look and perform similarly to one another but quite differently from the Japanese brands. Likewise, the Powerex (Taiwan) and Easypix (China) batteries are similar to each other in appearance and performance, and different from the others. My theory is that these brands of batteries are made by only three or four different manufacturers.

Which brand to choose is a matter of what you are using them for. If a really long life at low currents is important (e.g. as a clock battery), a brand with a high retention percentage in the seven-week test is the best choice. Those will hold their charge the longest, regardless of the initial capacity. If you will be using them over a relatively short period such as a few months in higher current applications (e.g. a digital camera you keep in your pocket or purse), choose one with a high absolute capacity and voltage in the seven-week test. The new Sanyo XX and Energizer Recharge are the clear winners for for short term high-current use, but for longer term applications, one of the lower rated capacity offerings is just as good, if not better.

Recommendations

To choose the best low self-discharge battery for your application, you have to know something about that application. If your device has a relatively high voltage (above 1.0V) at which it considers the battery to be dead, choose a brand with a high voltage under load. The Sanyos came out tops in the tests but the Duracell, Energizer, and Sony offerings were right up there with them. In selecting between these three, you may well decide based on other factors such as price, the fact that Sony uses the least amount of packaging material, or that Sanyo includes a reusable battery storage case.

If you’re interested in shorter term capacity, the Rayovacs do well right after being charged but quickly fall behind. They also have the lowest voltage under load, which may make their apparent capacity in some gadgets even lower. On the other hand, they can often be found locally at lower prices than the other brands.

What I did not test is how well these batteries will hold up after being recharged hundreds of times over the course of many years, and there’s really no way to know this without waiting those years to find out. The only data point I have in that regard is that the Sanyo Eneloop batteries that I’ve been using in my Nikon camera since January 2007 are still going strong, averaging 300 or more photos and three months between recharges. They are rated for 500 charge cycles (the second generation Eneloops are rated for 1500 cycles).

What About AAA Batteries?

Some of these batteries are available in the smaller AAA size as well, which I began testing in late 2009. Here are the results for the brands I’ve tested so far:

  E8GE Powerex Sanyo Tenergy
Date
tested		 Feb’10 Feb’10 Feb’10 Nov’10
Fresh Out of the Package
Capacity
(mAh)		 563 492 583 361
Energy
(mWh)		 587 498 624 360
Voltage
(V)		 1.04 1.01 1.07 1.00
Immediately after Recharging
Capacity
(mAh)		 734 743 773 857
Energy
(mWh)		 799 807 875 921
Voltage
(V)		 1.09 1.09 1.13 1.07
One Week after Recharging
Capacity
(mAh)		 658 649 726 770
Retention
(%)		 89.7 87.3 93.9 89.8
Energy
(mWh)		 697 664 784 813
Voltage
(V)		 1.06 1.02 1.08 1.06
Seven Weeks after Recharging
Capacity
(mAh)		 634 626 698 735
Retention
(%)		 86.4 84.3 90.3 85.8
Energy
(mWh)		 647 630 713 766
Voltage
(V)		 1.02 1.01 1.02 1.04
Long Term Predictions
6 Months
(mAh)		 554 550 608 625
12 Months
(mAh)		 482 481 526 528

The testing methodology was the same as for the AA batteries, except that charging and discharging were done at 400mA instead of 1200mA.

Note that although Energizer’s Recharge brand is also available in the AAA size, those are not advertised as having low self-discharge, so I have not tested them.

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Leave a Comment

128 Comments

  1. Mike
    March 01, 2009

    Hi Stefan, Thank you for your good work. I haven’t seen such a detailed test review from an independent tester. I have two comments: 1. Although a 1200 mA discharge current may be more realistic for real life simulation, it would be also valuable for end users to compare your results to the specs given by the manufacturers, which discharge their batts. at 400mA, as you say. This way we can compare apples to apples, and the only way to do it would be to discharge at 400mA.

    2. There’s a question of variance and QC. How many samples of each brand did you test? What is the variance of the different samples? Manufacturer A may have a better QC than manufacturer B, and your test results are effected by the statistics of your sample. For instance, the 7 week retention for the top three brands varies by a fraction of %. Is it higher or lower than the variance of each brand? Obviously, such a comprehensive test would be more time consuming.

  2. Stefan Vorkoetter
    March 01, 2009

    Mike, that’s a good idea to do a discharge test at 400mA. Obviously it’s too late to do a fresh-from-the-package test, but a test immediately after charging would be worthwhile.

    I tested exactly one set of 4 AAs from each manufacturer. As I pointed out in the article, the differences between the Duracell, Sanyo, and Sony offerings is so small that it can be ignored. It probably does fall within the margin of difference between batteries of the same brand. Ideally I would test far more of each brand, but as you said, that would be very time consuming. It would also be very expensive, since (so far) I’ve bought all the batteries I’ve tested.

  3. Gledy
    March 02, 2009

    I thought you did a decent scientific review and comparison of low-discharge batteries. If you are still interested in continuing this study there is a brand of battery called enelong. They are mainly sold on E-bay and I am curious how well they stack-up to the competition.

  4. Dick Clayton
    March 24, 2009

    Thanks for your informative article. I believe that the results you received for the 3 statistically same batteries is because the cells themselves were all manufactured by the same company in Japan no matter where they were assembled. Check this out.

  5. Arthur
    April 07, 2009

    Thanks very much for this information — it’s exactly what I was looking for. I’ll be back to see the updates from the 7-week tests.

  6. James
    May 15, 2009

    In case there was any doubt that the President’s Choice batteries are simply re-branded eneloops; I purchased a package containing a charger and 4 AA cells, and the charger has a PC logo sticker on the front, but a Sanyo logo is molded into the plastic on the rear face of the unit. Not to mention that the model # is NC-MQN06U, a charger that is typically sold with eneloop packs.

    Food for thought.

  7. em745
    May 28, 2009

    As your review confirms (what many peeps online know already), the "white top" Duracell Pre-charged, Sony CycleEnergy and President’s Choice are all Eneloop rebrands.

    As far as rebrands go, to make sure you’re getting real Eneloops, check to see if they’re vinyl-wrapped, are 2000 mAh rated, have a white insulator around the positive terminal, that the positive terminal has a very slight squarish shape, that the negative terminal has a ridge (typical of Sanyos), and, most importantly, that they’re made in Japan.

  8. dave
    May 28, 2009

    Does anyone have info on the Kodak brand Digital Camera Battery Pre-Charged (the white ones). They say 2100mAh and Made in China for Kodak. According to Wikipedia "Low self-discharge NiMH batteries are marketed with over twenty different brand names, but only actually manufactured by five companies: Sanyo, Gold Peak, Yuasa, Vapex and Uniross." But I haven’t been able to find who maked what ones.

  9. Tom
    June 06, 2009

    Your NiMh information has been most valuable. Are you planning to evaluate NiZn technology with the same depth? The 1.6 volt AA and AAA batteries such as the PowerGenix are an interesting addition to rechargeable battery options. There is discussion at this blog: http://www.depoteco.com/powergenix-nizn-batteries/

  10. Andy C
    August 05, 2009

    Thanks for the real world testing @ 1200 ma discharge rate. I’ve been discharging at 0.2C, but it’s good to know what typical ‘under load’ capacities would reveal. Looks like I’ll stay put with my eneloops, pc rechargeables and duraloops.

  11. f
    August 11, 2009

    I have heard/seen somewhere on the web that duracell now dont use enloops, but its a china manufacture

    The old ones use white tops, the new, lesser quality use black tops and are made in china. Will anybody confirm?

  12. Jan
    September 02, 2009

    Hi, Stefan: Do you by chance know the names of any of the specific factories that manufacture the better of these low self-discharge re-chargeables?

    Thanks. Jan

  13. Jean
    September 20, 2009

    Hi can someone tell me which AAA low self discharge batteries to buy for my digital camera. I’m so confused. jean

  14. Dimitar Dimitrov
    September 21, 2009

    Thank you Stefan. You help me too much.

  15. dbltapp
    November 10, 2009

    So – are you considering testing the PowerGenix NiZn cells?

  16. Thomas
    November 12, 2009

    Hi,

    great work!

    Are you planning to test the Vapex Instant 2100?

  17. CAMILO QUELQUEJEU
    November 16, 2009

    I have been using rechargeable AA Nickel Metal Hydride Batteries, since they first came out (Yuasa 1200 mAh). My conlusion was they were only good for high intensive discharge use ( Digital Cameras & Toys ) since they lost their charge so rapidly. You have opened my eyes to the changes that have ocurred in the new "Low Self-Discharge" version, the best being "Powerexs Imedion" ( Taiwan ) and its Chinese "Easy Pix" version; both probably made by the same factory or owners & just exported via different routes, since most Taiwanese Companies actually manufacture in China. What about the new AA Rechargeable Lithiun Ion Batteries. I understand they are the future, and the only thing that is stopping them from taking over completely today, is their High Price. They are mostly used in medical applications, and other equipment where money is of no concern ????? Do you know anything about the Lithium Ion ??? I believe the new Battery Operated Cars are using them ??? Should we wait for their price to come down to earth ???

  18. Tom
    November 20, 2009

    As happy as I am with Eneloop performance there was no resisting the PowerGenix NiZn low self discharge battery. While requiring a different charger to meet the needs of a nominal 1.6 volt battery and being only available in AA size, the PowerGenix seems to offer better performance than the Eneloop. Popular Science has just announced a "Best of What’s New Award" for PowerGenix. Including them in your battery and charger reviews would be most helpful. It appears that three PowerGenix can deliver the same voltage as four Eneloop. That might give an advantage to electric R/C planes. No one has a comparison of rechargeable batteries as comprehensive and clear as your reviews. Please keep it up! And thanks for your work.

  19. Stefan Vorkoetter
    December 17, 2009

    Tom (and others who have written to me about NiZn), you’ll be happy to know that I’ve got some PowerGenix NiZn batteries on order. I hope to start testing them in the next few weeks.

  20. Philipp
    January 13, 2010

    Hello Stefan!

    I would like to ask you about the new Rechargeable Lithium Ion Batteries AA. In a magazine I’ve read they have even a lesser discharge rate than the LSD NiMh. I would like to know if I can use them for my devices (e.g. mouse) which are meant to work with 1,5V batteries. The Li-Ion batteries all say 3,7V. I suppose it’s to much for normal devices. Am I right?

    Thanks in advance and best regards, Philipp

  21. Stefan Vorkoetter
    January 13, 2010

    I haven’t looked into these yet, but if they are indeed 3.7V, then you can’t use them directly. For devices using two AA batteries, you could use one AA Lithium-Ion and one dummy battery.

  22. Philipp
    January 15, 2010

    Thanks for your fast reply Stefan! So it won’t be worth it. I’ll try to get some Eneloop batteries.

    Thanks again!

  23. Mike
    February 08, 2010

    I just wanted to express my appreciation for your very informative page. I have so far used just standard NiMH rechargeables and have always been annoyed by the fairly high discharge rates. Your pages have given me a very good insight into what I can expect from the low-self-discharge batteries. This is so valuable over all the useless manufacturer’s (although the Sony eneloop page is quite good, too) or shops’ claims. Thanks a lot, Mike

  24. John t
    February 12, 2010

    Valuable information Sefan. I have the Panasonic charger (the R2’s are worn out) and went to look for the PC Choice but they only sell 4 with a charger.

    I’ll look around for the Eneloops

    Thanks.

  25. MikeH
    February 23, 2010

    I believe that the Duracell, PC and Sony precharged batteries are all rebranded Eneloops. I was hunting around several stores earlier this evening, and I found that PC were the lowest (sometimes Shoppers have Duracell on special, but not this week), so I grabbed a pack of PC.

    I also picked up one pack Energizer today. What’s interesting is that on the Energizer did not mentioned that it pre-charged, but the following caught my interest:

    – the cells are make in Japan – "now changed up to 150 more times (vs. older Energizer 2450mAh) – "last up to 4x longer (vs. Energizer MAX AA) – holds charge longer (vs. Energizer AA 2450mAh at six months)

    Plus the price was good (little less than $10 with coupon on the rack). It will be intersting to see how these Energizer AAs stack up.

  26. Tristan
    April 28, 2010

    These test results ask for a diagram. Not just a table with numbers.

  27. Sureo Mendez
    June 13, 2010

    These batteries (in my case the Sanyo Eneloop) have given my Canon A540 camera a new lease on life. The camera was rejecting several regular NiMH batteries, some brand new and fully charged, as needing recharge, and shutting off. After 2 months of intermittent use the camera is still happy with one pair of eneloops. Thanks for the review.

  28. alan
    June 15, 2010

    What an excellent and useful test, many thanks. I am using Sanyo eneloop in a camera and the improvement over the previous nimh batteries is immense.

  29. MArkH
    July 08, 2010

    Excellent report. Binned all my old NiMH and now use eneloop. Why not post a DONATE button on your site. I’m sure so many people have benefited from your reports that they would surely help to offset some of your costs.

  30. Stefan Vorkoetter
    July 08, 2010

    Thanks for the feedback. There is a donate button by the way. It’s just below this comment box.

  31. Daniel Rodrigue
    August 13, 2010

    Excellent review. It should however be noted that not all CycleEnergy from Sony are Pre-Charged low self discharge batteries. LSD from Sony are CycleEnergy Blue. If you buy CycleEnergy Green, you don’t have low self discharge. I suggest to specify "Sony CycleEnergy Blue" in your review.

  32. Stefan Vorkoetter
    August 13, 2010

    Thanks for the heads-up. I was not aware that there were two kinds of CycleEnergy cells from Sony. I have been unable to find the non-LSD ones that you’re referring to. Do you have a link to them?

  33. George Campbell-Kelly
    August 31, 2010

    This is a very useful article.

    I would be very interested to know what the sample size is for each of these batteries. Both within the same manufacture batch, and across batches.

    My personal opinion is that the results could well be within the margin of experimental error.

    Please do let me know…

  34. Stefan Vorkoetter
    September 01, 2010

    Most of the tests involved two packs of 4 per manufacturer. I’d agree about the margin of error, except that if you compare all the Sanyo-manufactured brands to the rest, you’ll notice that they are consistently better than the non-Sanyo ones.

  35. Michele Kuraoka
    September 11, 2010

    Thank you for your reviews, it was very interesting reading.

    I have a question. I use my digital camera to take videos and photos, especially at concerts. I tend to use my camera more for the video function than the photo function at concerts. I may have the camera on for a 90 min. period. In between, I am also turning the camera off and on. My camera takes 2 AA batteries and I was wondering if you would know if the Sanyo Eneloop batteries would be able to last the entire 90 min. period without having to change the batteries. Currently, I am using Energizer rechargeable NiMH batteries and I have the 15 min. charger. Would you recommend the Sanyo Eneloop batteries for my digital camera -video use? Thank you.

  36. Stefan Vorkoetter
    September 11, 2010

    Michele, it’s hard to say without knowing how much current your camera uses, but I would say most likely yes. Although the Energizers’ rated capacity is higher, that’s only when they’re brand new. After a few recharges, they tend to lose capacity in my experience. By the way, don’t use the 15 minute charger on the Eneloops. You will ruin them in short order (the same goes for the Energizers).

  37. Gavin Owen
    September 11, 2010

    I say stick to that Japanese ones. It’s handy to have two brands because when you are in the field you can tell what’s what. ie. for my Canon 580EXII flash I bought a 4-pack of Sony Cycle Energy and a 4-pack of Sanyo Eneloops. I can then keep a mental note of which group of batteries is charged or drained, and don’t get the charged ones mixed with the flat ones when I pull them all out on the table with the charger.

  38. Stefan Vorkoetter
    September 12, 2010

    That’s a great idea about the two brands. I always tried to keep them straight by putting them in different storage cases, but mix-ups are inevitable.

  39. George Francis Bernard
    September 20, 2010

    So was the test in the AAA batteries between Sanyo Eneloop, and Powerex Imedion, I rarely seem to need AA?

  40. George Francis Bernard
    September 20, 2010

    Because http://protog.com.au/powerex-imedion-800mah-aaa-rechargeable-batteries-4pk-p-73.html I found.

  41. George Francis Bernard
    September 20, 2010

    Reading about the 15 min. charger, charging at 2500mA doesn’t produce those kind of side effects does it?

  42. Stefan Vorkoetter
    September 20, 2010

    George, the AAA test was between the four brands listed in the results: E8GE, Powerex, Sanyo, and Tenergy. The Tenergy tests are still in progress. Regarding charging at 2500mA, that’s a very high charge rate for AA (under an hour), and an extremely high rate for AAA (about 20 minutes). I personally wouldn’t use anything much faster than a 1.5-hour charger on any AA or AAA NiMH battery. That translates into about 1300mA for AA, and 500mA for AAA. I wrote more about the dangers of super-fast chargers in my Using NiMH article: http://www.stefanv.com/electronics/using_nimh.html

  43. Petr Antoš
    November 06, 2010

    Apropo LSD znamená taky … “Low Self-Discharge” 🙂 Tzn. poznají se podle toho že se prodávají “prednabité”, což je jen hezký vedlejší efekt toho jak jsou dobré. Už to delají i jiní, ale sanyo bylo vždycky v akumulátorech bezpecne nejlepší ….

  44. Stefan Vorkoetter
    November 15, 2010

    I’ve just added the final test results for Tenergy’s AA and AAA Centura batteries. The AAs are about middle of the road, but the AAAs have the highest capacity of any of the brands tested. Their charge retention isn’t as good, but for periods of up to 3 months or so, the overall higher capacity more than makes up for this.

  45. Tom Naughton
    December 08, 2010

    Thanks. A littel feedback on long term cell life. Read your review in 2007, got a 4 pack of Eneloop for a very finicky Fuji FinePix camera that seems to have a very high V = “dead” value, and was very happy with capacity and shelf life. Used on and off for years, heavy use 5-6 times a year and moderate the rest.

    By 2009 shelf life and capacity weren’t lasting as long, especially one pair of the 4. Still acceptable but I think both capacity and voltage were dropping off; certainly dying faster in the camera after short storage. Bought a pair of Eneloops with in a 4 Hr charger for a summer vacation trip. The new 2009’s were worse at holding their charge (or maybe voltage) than the good 2007 pair, even with my old, slower charger. They never improved. I can still trust the good pair from 2007, but the others I treat like regular NiMH’s and charge fresh before use when possible. I cary a pair of Lithium batteries as back up now, instead of the 2nd pair of Enaloops.

    I’m back to look again for replacements, but Eneloop still looks like the best for my finicky camera.

    And a note on keeping track of charged and flat batteries I saw below. I store the charged with the name facing out and the dead with the back facing out. Works unless the rotat on you…

  46. Phillip Lynch
    January 06, 2011

    your spot on with your report my workhorse is the Duracell precharge AA

  47. Jane Freund
    February 01, 2011

    Can Sanyo Eneloop be recharged in any AA battery recharger. And can the Enelope recharger charge other AA batteries?

  48. Stefan Vorkoetter
    February 02, 2011

    Yes, any good quality NiMH charger can be used, but stay away from any charger that charges in 1 hour or less. It’s best to stay with ones that take over 2 hours. Charging too quickly can damage the batteries.

    In answer to your second question, yes, the Sanyo charger can handle any NiMH rechargeable batteries.

    Don’t put NiMH batteries in rechargeable-alkaline chargers or vice versa though.

  49. MikeW
    February 06, 2011

    I too use Eneloops – have the later: HR-3UTGA version beats the pants off the …..UTG version and now wouldn’t be without them. I use in Canon digital which is, I think, more voltage sensitive than some cameras and a pair will shoot an hours worth of 640×480 video and still be going strong. I leave them for 2-3 weeks no problems unlike previous Eneloops which come up as change batteries after a few minutes in camera. Have tries supposedly low loss make but not even close to Eneloops

  50. Stefan Vorkoetter
    February 09, 2011

    Hi Anonymous: I’ ve been using the original Eneloops I bought in 2007 in my Nikon 8700 since the beginning, and they _still_ last 3 months and/or 300 shots between charges.

  51. humanityrultz
    February 11, 2011

    Hey your material is really helpful… Thanks for uploading all your tests…

    I am new to this battery world…I am lokking for battery charger…but no luck ,, until now…

    I want to use..4AA NiMH batteries…Before I buy I want to know..

    how can I charge them using wall charger.. I mean.. there are lot of wall charger out in market which we have to take batteries out from products(like toys or hand operators….) to charge…. but I am looking for charger which charge by plug in socket.. with out designing any ckt to protect batteries.. means I am looking for wall charger with protection ckt in it with small DC power plug.. to connect to the Batteries directly ito product.. without taking batteries out………

    suggest me …If you get me and know any ??????

  52. Stefan Vorkoetter
    February 12, 2011

    Anonymous, to charge batteries that are still installed in a device, you need a NiMH wall charger that is specific to that device. Some devices (e.g. my Canon digital camera) do not allow charging inside the camera.

  53. Ajo Mathew
    February 12, 2011

    is there any problem if I use a Nikkon Charger for my eneloop AA battery. My camera is nikon CoolPIX L1

  54. humanityrultz
    February 14, 2011

    THANKS FOR RESPONSE, I am using battery powered device, where I used 4 AA NiMH , I want charge these batteries without taking them out of device, I want to know is there any wall chargers out in market, will charge in 2-8 hours time? Suggest me, I tried look in to various sites and googled it but no luck… I am using Sanyo recharge AA NiMH cell,2500mAh 1.2V (4 BATTERIES FOR MY APPLICATION). or guide me which charger do I have to use?

  55. humanityrultz
    February 14, 2011

    Any way I don’t know much about batteries, until I found your articles, after that I selected SANYO batteries though….Thanks once again for all your posts..

  56. Stefan Vorkoetter
    February 14, 2011

    Ajo, if your Nikon charger is designed for AA NiMH batteries, then it will work fine for Eneloops.

  57. Stefan Vorkoetter
    February 14, 2011

    Anonymous, as I mentioned in my previous message, you need a charger designed for that device. In other words, the charger provided by the manufacturer. If the manufacturer does not provide a charger for the device, then it is probably not possible to charge the batteries in the device. Check the device’s manual.

  58. BatteryUser
    February 17, 2011

    Been using eneloops with fairly good luck.

    I go through about 8 a day so I thought I’d try the 2400 mah powerex batteries. Can’t really tell much yet, but they didn’t come charged I can tell you. Cycled them through my maha c9000 and time will tell if they work about better than the eneloops.

  59. Christian StClaire
    February 17, 2011

    Hello Stefan, I have to command you, well done!

    However it would be nice to see the advertised capacity on your chart “once in top + once at middle” just as a reference point since it is what we use often in purchasing decision

    such could be highlighted in Red or some easily readable color.

    On another note, unbelievable the stuff I received from China lately bought off eBay, Counterfeit basically both in NiMh + Lithium.

    ex.lithium 2000 mah 3.7volt for my HTC Evo 4G (OEM is true 1500mah)

    they tested to only 1397mah, I bought 12 of them for my EVO friends, got reimbursed by Paypal.

    First clue was the weight,way under OEM’s weight

    (this remind me to suggest you also include the weight in grams (to one decimal if you can)

    Most people do not have the equipment that we have nor our passion for energy anything & get taken whitout knowing it,

    They just wonder why their phone’s battery or else die too quickly. LOL but sad.

    Same exist with counterfeit memory card, if anyone wants to know more, just ask & I will let you know what is going on technically with these scams.

    Sorry Stefan, long post.

    Well deserved Donation on its way to you. feel free to communicate privately through my FaceBook listed email.

    Again many thanks & Regards. Christian StClaire en Californie

  60. Bling Bling Tulip
    March 02, 2011

    If anyone wants to buy reusable batteries, read this article before you do!!!

  61. ll1542
    March 05, 2011

    Hi i am wondering if anyone has used the accuevolution LSD batteries. They make a lot of bold claims so I am skeptical. Would love to see more independent data on them. thanks.

  62. Jim Ashmore
    March 06, 2011

    Thanks for doing this research. I was always wondering why my rechargeable batteries discharged within a week of charging.

  63. Abdul Halim bin Ali
    March 18, 2011

    million thanx for providing this useful info

  64. Diego Fernández Carvajal
    March 25, 2011

    Gracias por el estudio, muy interesante.

  65. Cumhur Cemal Özmen
    March 25, 2011

    Do you recommend Varta “Ready2Use” AAA 800mAh ? I will buy it for my MP3 player. By the way Stay away from samsung they clearly fail at quality. Their 900mAh Pleomax was a epic fail. I measured 540mAh for one of them. It is a real disgrace

  66. Fleming Wang
    March 25, 2011

    Thank you very much for the effort, which save me lots of time and money to make choice.

  67. Stefan Vorkoetter
    March 28, 2011

    Cumhur, I’ve never tested the Varta “Ready 2 Use” batteries, but Varta is a good brand. I have a 14 year old set of Varta NiMH batteries that still work well.

  68. Andrew Kantor
    April 08, 2011

    Great info, although I’m curious about the number of recharge cycles each of these can handle. The Eneloops look great, but can they really handle the 1,500 cycles Sanyo claims? I’d rather buy something that shows lower capacity but can handle a lot more cycles. (And yeah, I know it’s out of the realm of your testing. I’m just musing aloud. 🙂

  69. Stefan Vorkoetter
    April 08, 2011

    Andrew, you’re right that that’s outside the realm of my testing (since it would take years), but my experience with Sanyo batteries in general is that they live up to their claims. I used to use Sanyo NiCds for electric powered model aircraft, and they would easily last hundreds of cycles despite the abuse (high charge rates and extremely high discharge rates) that I put them through.

    I suspect that with the Eneloops and other low self-discharge batteries, that they may die of old age before actually hitting their maximum number of cycles, simply because in many applications, you rarely have to recharge them (the Eneloops in my Nikon camera have been charged only about a dozen times in the last three years).

  70. David Sims
    April 29, 2011

    I use Eneloop AA and AAA size batteries. I don’t use their spacers for C or D, because I don’t like under-capacity cells. For the C and D and 9V batteries, I use Tenergy Centura’s “real” full size batteries.

  71. Stefan Vorkoetter
    May 01, 2011

    David, I agree about under-capacity cells. But the only thing I used C-sized cells in is my Roomba vacuum’s “virtual walls”, and those use little enough power that AAs in (homemade) spacers work fine. I recently reviewed Tenergy’s 9V Centuras, and am very happy with them (see the link in the lsit of articles above).

  72. Alex
    May 17, 2011

    Hi Stefan,

    Thanks for your valuable work. To my mind, the Energizer Recharge AA appear to be the best batteries on test, as they either have best or 2nd best capacity and voltage at each of your actual test stages. I’m surprised that you didn’t recommend these as the overall best choice, but I note that you marked them as “testing in progress” so perhaps you added these figures later on. Could you help me by identifying exactly which type of Energizer battery you tested, as there are a variety of notional capacities on the market, none of which actively claim to be LSD. I don’t want to buy the wrong ones, as elsewhere on the web the views of Energizers is not very good…

  73. Tran Tuan Ha
    May 27, 2011

    Thank you very much for all your articles, really detail and useful

  74. Mauro Bonazzi
    June 09, 2011

    Excelent article. I want to ask you permission to translate some of your articles into spanish and place them in another page called Taringa. It is an Argentinian webpage (www.taringa.net) Of course i will place your name as the writer of the article and this webpage as the source.

    Also, one question, did you know that alcaline batterys actually can be recharged? For what i have read, in japan companies can’t put that such batteries can not be recharged or a similar legend.

  75. Avinash Lewis
    June 28, 2011

    Hi Stefan, i had at least 8 Nikon cameras from L10/L11/L13/L16/L18/L21/23 to now latest L120,L120 uses 4 AA, i have used sanyo Eneloop for about 4Years now without any visible wear..you review is amazingly accurate, I keep eagles eye on batteries with My Fluke multimeter.

  76. Ken Ahlstrom
    July 04, 2011

    Excellent article. I have gone through many of the older “regular” NiMH rechargeable batteries before discovering the Powerex Imedion batteries about a year ago. Oh what a difference. I am delighted at their performance.

    Thanks for such valuable information.

  77. Juan Medina
    August 25, 2011

    Hi Stefan. Good job, I agreed with your results, in the part I know some of the batteries you tested, not all of them.

  78. André Aguiar Fotografia
    August 25, 2011

    Excelent article!!

  79. Dhaval Jani
    September 02, 2011

    wow great work man…..thanx…

  80. Mroslaw Zielinski
    September 17, 2011

    Your article is very good. I have few set of 4 Eneloop and PC and I love it. If you are professional photographer regular NiMH (daily use) AA are good but pain in ass when in storage for a few months. After 8 months Eneloop and PC batteries lost just 400mAh of capacity but NiMH have been dead (waste of money for occasional user as me).Thanks.

  81. Benjamin Lin
    October 01, 2011

    I started with Eneloop few years back, and they’re the only recharable batteries I’m using now…

  82. Bob Tremblay
    October 10, 2011

    Hi, nice article, but what is the rating of each battery ? 2Ah ?

  83. Saket Bajaj
    October 28, 2011

    Very good article. I had bought a set of 4 Eneloops for my new Fujifilm HS20 EXR camera and it gives me about 500+ shots every charge. I love the eneloops….

  84. Er Bello de Monterverde
    December 05, 2011

    Hi, thank you for your useful tests. I’ve just discovered that amazon is selling pre-charged batteries too. Did you have the chance to test them? I looks to me (by making a search with the product number, for ex. H-AAA800AS) that the batteries are produced by FOREVER BATTERY CO. The company provides datasheets, however not for the very same products (I found H-AAA800A, without the final ‘S’), but they’re not very detailed.

    The price is really good, so I was wondering whether it’d be worth it to buy some!

  85. ed parauka
    March 11, 2012

    I have the Kodak camera dock II, with its capacity to recharge batteries while in the camera. Can I use the Sanyo eneloop rechargeable batteries in my Kodak camera on the dock for recharging? Kodak manual says you have to use Kodak batteries. Thanks for any info, Ed Parauka

  86. Stefan Vorkoetter
    March 11, 2012

    Ed, if the camera uses NiMH batteries then yes, you can use Eneloops. However, like any NiMH battery, if the charger is just a dumb (overnight) charger, don’t leave the camera connected too long.

  87. ed parauka
    March 11, 2012

    Thanks Stefan for the quick reply and info. You have a very interesting and useful website. Keep up the good work. Ed

  88. Scott
    April 04, 2012

    I recently purchased a Sanyo Eneloop package with 2000mah AA and 800mah AAA celss which included the NC-MQN06U charger. Can it also charge the Sanyo Eneloop 2500mah XX AA cells?
    Thanks,
    Scott

  89. Stefan Vorkoetter
    April 04, 2012

    Yes, the regular Eneloop charger can charge the XX cells. It will just take about 25% longer, that’s all.

  90. Jeannie
    April 18, 2012

    While I realize that it was done for testing purposes, I was shocked to see you used 1200 mA to charge the batteries. Heat is what kills batteries and charging at 1200 mA will eventually BBQ the little buggers. You might as well marinate them before charging. I never charge at any more than 200 mA (it takes longer to charge, roughly 12 hours or so, but then I can just plug them in and walk away, letting the charger do its thing). I wish I had a lower setting since my AAAs get pretty warm at 200 mA but, so far, it doesn’t seem to have hurt them.

    A 1200 mA discharge rate is not likely to do any damage when used in a high draw device, such as a camera, since the current draw is intermittant. If that high of a draw was continuous, the battery would eventually wind up well done (and needing BBQ sauce).

    I have two smart chargers, a BC900 and a BC700, both by La Crosse. The BC700 has more than enough capacity for charging up to four AAs or AAAs (you can mix the two types) but I got the larger charge rate capacity BC900U (it has since been replaced by the BC9000) to get the soft storage case that came with it (it has room for both chargers and their wall warts, and 16 each of AAs and AAAs when stored in little cases of four). The chargers taper off as the batteries approach full charge then drop to a trickle when fully charged. I can just walk away and leave them wihout worrying that they will overcharge.

    I’ve been using Eneloops in all my devices that use AAs and AAAs since January of 2009, buying more as I acquired new devices. I have yet to have one fail and all seem to still be going strong (I quit testing them after the first year because it was just a waste of time since they always tested out fine). Because my big camera and external flash use 8 AAs each, the e-book reader I carry in my purse uses 4 AAs, and the small camera in my purse uses 2 AAs, I carry 16 spare AAs in my purse. I also have numerous devices in my purse that use AAAs (flashlight, a power hungry audio recorder, and a lighted magnifier) so I also carry 16 spare AAAs in my purse. I also keep 16 spares of each size in my charger case (it stays at home unless I’m travelling). That many spares are handy when away from the house but they also allow me to go really nuts with my cameras, etc. without having to worry about how long it takes to charge my batteries since I have plenty of spares to hold me. I have yet to run out.

    I charge all of the batteries, whether they need it or not, in January of every year just to make sure they are all up to snuff since I don’t worry much about rotating the spares anymore (I found it just didn’t make any noticeable difference in performance).

    A while ago, I threw a AAA that hadn’t been recharged in several months across my VOM and it was still showing 1.32V no load. I’ve found the Eneloops will charge up to 1.5V, discharge down to around 1.35v in a week or two, then hold that charge for at least a year (probably longer but I never let them go longer than a year). When in use, the voltage stays pretty flat until almost discharged, then drops off quickly. When my cameras or e-book reader say the batteries are starting to get low, it means change out the batteries NOW! That hasn’t been a problem with the cameras since it takes less than a minute to dig out spares from my purse (or pocket if I’m too lazy to lug my purse around) and swap them out. The e-book reader takes longer only because it has to reboot but, even then, it’s only a couple of addition minutes (big deal!).

    There may be better batteries than the Eneloops out there but I’ve been more than happy with them since they are reliable and very economical (the up front cost is a bit high but, in the long run, they beat the beg, fat, hairy heck out of alkalines; I’ve also never had one leak, unlike alkalines). I will continue to use them so all my batteries are the same brand (easier than worrying about mixing brands).

  91. Stefan Vorkoetter
    April 18, 2012

    Jeannie, although 1200mA is a little high (normally I wouldn’t recommend going above C/2, which would be 1000mA for these 2000mAh Eneloops), they only got warm, not hot. If the charger is good enough to be able to accurately detect the peak (voltage starts to drop after full charge is reached), rates this high won’t bother them.

    All of my Eneloops are still going strong too, including the ones I originally tested in 2007 and which each have several 1200mA charge and discharge cycles on them. My regular charging is done at 500mA, or 1000mA if I’m in a hurry.

    No-load voltage isn’t a very useful indicator of the remaining capacity of a battery. It’s sort of like measuring the acceleration ability of your car while driving down a nearly vertical hill. My Saturn would do nearly as well as a Formula-1 race car. 🙂

    By the way, your purse must be heavy with all those gadgets and spare batteries!

  92. Jeannie
    April 18, 2012

    We must have different ideas of warm and hot. When I first got the first charger, I tried charging at 1000 mA just to see what would happen and bloody near burned myself on the batteries! My AAAs get rather warm, even at 200 mA.

    Even if the batteries can handle the higher charge currents, I prefer to take it easy just to be on the safe side and ensure long life (yeah, I’m cheap old bi…broad). At my age, I don’t do anything in a hurry anymore. Besides, I carry enough spares I don’t need to charge in a hurry.

    I agree that no load voltage is pretty much useless for measuring the remaining capacity of an Eneloop (lead acid cells are a different story) because of the nearly flat discharge rate for most of the life. As far as I know, there is no accurate way to measure remaining life in a NiMH. I just don’t worry about it. It takes little time to swap them out so I just let them run down, then change them. Occasionally, if I’m going to be taking a lot of pictures in a short amount of time, I’ll swap in some new ones before starting. The battery “meters” on most devices are designed to work with alkalines so the readings are always off. By the time the “meter” shows the battery is low, the battery is actually pretty much depleted and will lose voltage quickly.

    My chargers measure total charge capacity by putting a full charge on the battery, then discharging it while timing the discharge, then recharging it again.

    Yeah, it’s a heavy purse. So heavy, in fact, I had to register it with the police as a lethal weapon. All seriousness aside, it only weighs four pounds. I don’t carry the big camera and external flash in it.

  93. Stefan Vorkoetter
    April 19, 2012

    No, we probably agree on warm vs. hot. But the cells won’t get hot if the charger cuts off immediately when they are fully charged.

    It is possible to get an approximate measurement of the level of charge in a NiMH battery using an expanded scale voltmeter that also puts a load on the battery. For example, this one.

    My charger also measures total charge the same way. Here’s a detailed article describing its design and construction.

  94. Jeannie
    April 19, 2012

    Curious, when charging at 1000 mA, my batteries got too hot to comfortably touch well before they were fully charged.

  95. Rob
    May 10, 2012

    Stefan,
    Thanks for your review. I read several and think you said you know just keep a stock pile of charged batteries and grab what you need. Is there a problem with mixing batteries (same manufacturer), that have been charged a different number of times? I am assuming that they should be kept in sets, so the charge/recharge cycles are the same?
    Thanks
    Rob

  96. Jason Coleman
    May 18, 2012

    I just picked up a set of Energizer AAA rechargeable batteries. I was looking for Eneloops but no one carries them locally, and I am in a hurry. Anyway, reading the package, I think that the wording implies they are low-self discharge, even if it doesn’t say those exact words. The packaging I have is labeled “pre-charged” and also says they will hold a charge up to a year when not in use. That sounds like low-self discharge to me. What do you think? And, would you do a test of them now, if they sound low-self discharge to you?
    Thanks!

  97. Ron
    May 25, 2012

    Thanks Stefan for the great article, I also enjoyed all the chat afterwards, it kinda feeds the debate that much more. I’m not an extreme greenie but I do tend to like the idea of these rechargeables and I’ve been using NiMH for years for environmental reasons. Anyhow, I have to agree with several other posts in regards to doing a test on the NiMH batteries that would be comparable to the tests that the battery companies perform to evaluate the Alkaline batteries, which is about a 250mah drain test. I agree with you that it’s not a realistic real world test, but this is a WAR! Oooops, stay calm, stay calm, where was I. Oh yea, I am convinced that the battery companies are not really interested in selling rechargeables, but must in order to keep pace with the competition so they tend to push the Alkaline batteries as the battery that keeps going and going and going. Not including shelf life issues these NiMH batteries are in reach of the Alkalines but nobody publishes that. All I’m really trying to say is that doing a true comparative test between the two might make it easier to swing some of my “Alkie” friends over to the rechargeable side. Just a note on the NiZn, do they really start off at 1.8vdc? I personally wouldn’t think that that would be a good thing. Again, thanks for the well written article.

  98. Mauro
    June 22, 2012

    Stefan, quick question. I´m looking for a good long life recharchable batterie for my cordless phone. For what i could understand, the one that shows the best long life capacity is the Duracell, isn´t it?

  99. Vinny D
    July 03, 2012

    Hello Stefan,
    Great article and info, I commend you on your time taken to provide info like this for the battery user community. I have been a RC plane flyer for about 25 years now, we have seen allot of amazing changes in our hobby especially in electric flight and guidance technology-50 airplanes stored in 1 radio!
    It appears with the slow removal of Ni Cads we must search for others means to power our flying apparatuses safely; this is where my confusion starts-I am a creature of habit and don’t take change to good. I recently purchased eneloops from my local store and a little concerned with using them in some applications with 2.4 ghz Rx RC radios and giant scale gasoline airplanes, or should I say the rc forum rumor mill that is driving me crazy-some say yes-some say no-who do I believe?
    Some RC battery suppliers claim that eneloops can not with stand vibrations and heat like nicads, it is hard for me to believe using the eneloops wrapped in foam away from engine heat per our normal old nicad set-up (do’s & don’ts) would cause any problems-what’s your thoughts?
    My other concern is amp draw per voltage drop via high eneloop impedance with 2.4 radio’s-(brown outs). Presently my normal nicad set-up is (two) 5 cells 2500 mah packs paralleled to Rx on separate switches, 1 plug into Rx battery input, the other into and open channel that I have been doing for years. Recently I used 2 of the 5 cell eneloop 2000 mah packs in my A6M Zero powering 8 servo’s, 10 flights later I have had no problems and the Rx peg my esvm out after each flight-amazing, I have never had any nicads do that– great batteries! Again, after doing some reading I started to get concerned with a 27 lbs airplane going over 100mph— I know little late for that- not very smart on my part. Anyway, I know it’s hard for you to come up with a solid # without all specs, what do you think the max amps eneloops batteries could withstand before they drop out a Spectrum 2.4 Rx. I am not 3-D ing, this old dog don’t think that fast anymore, all servos are not in full deflection, when I fly-mainly ailerons, elevator, throttle movement, then momentary landing gear & flaps. Also I am just wondering is there any way I can easily calculate servo amp draw per my airplane application?
    Thanks for your time, Vinny

  100. Peter MacCabe
    July 10, 2012

    Didn’t realise the significance of any of this until I decided to buy some Sanyo Eneloops for my Nikon F5. It has sparked off an AWFUL lot of things in my head.LSD NiMH technology has the potential to bury Alkaline technology forever-at least in the current sense.All I need to find out about now is a recommended LSD NiMH ‘D’ Cell of at least 9000 mAh and a recommended charger to charge at least six. Thanks very much for these superb articles btw-pretty unique AFAIK.

  101. Stefan Vorkoetter
    July 24, 2012

    Vinny, I’ve never tried using Eneloops in exactly the application you’re using. I do fly R/C, but all my models are fairly small, and being electric powered, draw their Rx/servo power from the main motor battery via a voltage regulator, so I don’t actually use any Rx packs at all.

    What I suggest you do is set up your plane as usual, and then plug a digital voltmeter into another unused channel. Turn everything on, and start stirring those sticks to get all the servos moving, and monitor the voltage that is getting to the receiver. Be sure to try the retracts and flaps too. If the voltage never drops below 6V (since you’re using 5 cell packs), you ought to be fine.

    I really doubt that Eneloops are any more prone to vibration damage than any other AA NiCd or NiMH cells. Given the size of your plane though, it’s good that you have the redundancy of two packs.

  102. Rohit
    August 19, 2012

    Hi,
    I recently came across
    ‘harmolattice’ batteries by Sanyo.
    Can someone throw some light on their
    performance when compared to the eneloop XX.

    Thanks,
    Rohit

  103. Betsy
    September 07, 2012

    Hi:

    I just bought a pack of eneloop XX batteries. I have the energizer charger can I use the charger for the eneloop batteries????

    Thanks,
    Betsy

  104. Charlene
    September 07, 2012

    Just a small (?) clarification on the Maha Energy batteries on this website: PowerEx is a low cost, high discharge battery brand from Maha; Imedion is the high cost, low discharge battery brand from Maha. I don’t think there is a PowerEx Imedion battery. So, I’d like to see a test of Tenergy low discharge batteries vs. Maha Imedion low discharge batteries if possible.

  105. Stefan Vorkoetter
    September 07, 2012

    Charlene, the packaging for the Imedions says Powerex right on it. Take a look at this page right on Maha’s own web site: http://www.mahaenergy.com/store/viewitem.asp?idproduct=426

    Regarding comparison with the Tenergy low discharge batteries (Centura), both are in my test results in this article.

  106. Rich
    September 11, 2012

    Hi Stefan,

    I just purchased a Sanyo Eneloop combo pack, both AA and AAA. I’ve read that although these do come charged and ready to use they actually are not fully charged. Would it be be a good idea to charge them before use?

    Thanks

  107. Stefan Vorkoetter
    September 11, 2012

    Yes, charging them would be fine. They are charged to about 70% capacity at the factory. Just make sure you’re using a smart charger, and one that is no faster than 2 hours.

  108. Rich
    September 11, 2012

    Thanks Stefan, I’m using the Sanyo charger that came with it. I was not sure if it would effect the life or full capacity in the long run if I did not charge it fully. Thanks, great site by the way!

  109. Larry
    November 28, 2012

    I just read through everything hear and I am in agreement with lots of what Charlene was talking about; charging the battery’s at a slow rate.

    My AA’s are 1st charged on the Maha 9000 in the “break in” mode (35hrs) and I really believe that this has made my battery’s hold a charge longer while sitting idle. After 6 mo’s the standard Sanyo 2700’s are down only 20%, with a couple still holding 100%. Now, these battery’s have not cycled more than 3 times.

    I have around 95 rechargeables, AA, AAA, C, D and 18650’s and they have never been charged in a fast mode.

    I have tried Tenergy, Sanyo (xx and standard) Powerex (Imedion and Standard)- The Sanyo standard Ni 2700 seem to work the best for me, but I also do like the Sanyo XX too.

    As far as the D cell goes, the Powerex are really good and so is the AccuEvolution LSD. The A/Evolutions hold a good charge for many many months while in the flashlight.

    Oh by the way – good testing you did there Stefan!!

  110. Clive
    December 06, 2012

    Hi Stefan,

    Thanks for all the the reviews they are very helpful.

    Have you heard of or tried Ansmann Maxe batteries they seem to offer 2500mAh capacity but retain the 1500 charge cycles unlike the Eneloop that drop to 500 cycles at the higher capacity?

    I use an Ansmann charger so have a certain affinity for that brand, however it is more than probable they are made in the same factory as other brands.

  111. Clive
    December 06, 2012

    An update to my previous post!

    It appears I was mistaken in believing the Ansmann has a higher number of cycles because I have just found the manufacturer’s PDF which shows a charge cycle rating of 500+. This adds weight to the belief that all these batteries are made in a few factories to similar standards.

    However possibly more importantly it seems the lower capacity 2000mAh cells are better value being cheaper with potentially 3 times greater life. So unless you actually need the higher capacity for a particular application it would make more sense to buy the lower capacity.

  112. Waxy
    December 18, 2012

    Several years ago I purchased at least 20 Powerex 2700 mAh standard nimh AA batteries and about 20 Powerex Imedion 2100 mAh low-discharge AA batteries. After 5 years of fairly regular use (perhaps 1 charge cycles per week), all of the standard nimh 2700 mAh batteries failed. I tried refreshing them using a LaCross Bc-900 charger (the refresh process ran for many days), but they never held a charge again. I had to discard all of them. However, the low-discharge Imedion batteries are still going strong.

    I’ve purchased only Eneloops since then. The Powerex 2700 mAh batteries were really quite disappointing. Is there any consensus as to which brand have the longest service life? I’m guessing its hard to beat Sanyo Eneloop

  113. Tom G
    December 23, 2012

    How about 9v rechargeable batteries? Does Sanyo make them?

  114. Stefan Vorkoetter
    December 25, 2012

    Tom, I don’t think Sanyo makes 9V rechargeables, but I did do a review of Tenergy’s 9V offering: http://www.stefanv.com/electronics/9v_rechargeable.html

  115. crabpaws
    December 27, 2012

    Excellent article, thank you.

    Agree with the others that results would be enhanced by a more easily interpreted chart, perhaps with rankings for different applications.

    In the meantime, I’ll be buying Energizer and Eneloops.

  116. VICENTE CARDONE
    December 28, 2012

    Certanly this work is the best and most detailed I can find in the Internet about how to choose rechargeable batteries: THANKS VERY MUCH. Just now I have 8 Eneloops and 8 Ray O Vac Hybrid working in my photography equipment (camera and flashes) with excellent and similar results; another 6 Duracell live in my daughther toys from a very near time. All are 2.000 mAh capacity. I buy this brands because all of them show good results in Stefan examination and was what I found in that moment available in the store. My Preference is Eneloop, Duracell and Ray O Vac in that order.

  117. Larry
    December 30, 2012

    Tom – Sanyo does make a 9v battery.

  118. Larry
    December 30, 2012

    Woops, sorry Tom, it’s only a Primary 9v not rechargeable.

  119. sherlym27
    March 27, 2013

    Really it’s a nice article.

    I wrote the article concerning Li-ion batteries Do’s and Don’ts. I hope you its may help you.

    http://goarticles.com/article/Be-Conscious-of-Your-Li-Ion-Lithium-Ion-Batteries/7486068/

  120. David
    June 18, 2013

    What about Ansmann e-max? Anyone any thoughts\tests? Why were those skipped?

  121. Stefan Vorkoetter
    June 18, 2013

    David, they weren’t skipped. I just haven’t been able to get a hold of any.

  122. Tracy Sunshine
    October 28, 2013

    We use rechargeable batteries in our Game cams, and we have 3 of them, 2 that take 12 aa batteries… We bought the tenergy with the charger and love it, but want to get more batteries to have for other things and some times we have to change batteries often on one of the cameras, so still don’t get whether or not the low self thing means anything to us at all, we charge them and then put them in a couple hours later, since we use it all year round, does the self discharge thing only matter if the batteries are sitting around or do they last longer in a device such as the game cams that take video’s every so often and motion makes it start? I am confused.. should I just order more of the tenergy as we seem to like them,,, and they don’t say anything about self discharging.. they are the blue ones and so far so good and its been over a year or longer. so in the device does that make a difference and make us have to change them less often or does that mean that they can sit on the shelf longer till we have to change them? thank!

  123. Avinash Lewis
    December 11, 2013

    Dear Stefanv,

    Thanks for the wonderful review,
    I was looking for Duracell Pre-charged figures and your are the best i can find on Internet, Keep up with the good work

    Regards
    Avinash Lewis
    Senior Engineer UN, IAEA

  124. William B.
    May 23, 2014

    Thanks, Stefan, for this useful study. With rapid changes in technology, the hard data gets out of date fast, but the comparisons are nonetheless valid. It seems the best guide is going to be the “Made in”. Pick Japan over China.

    I’ve had the same experience as Waxy with the standard Powerex batteries. They seemed great, and then they were just about dead, and at a very inconvenient time. I had fooled myself using a voltmeter to think they were still OK. Now I use the Delkin battery tester, and my current Powerex Imedions (2400mAh claimed) are beginning to seem like their older cousins. Compared to Eneloops (1900mAh), they drop fast in use.

    I’ve put both the Imedions and Eneloops in a motorized tripod head. The iPad app that controls the tripod and camera, immediately with newly charged Imedions or Eneloops shows 50% charged (2 of 4 bars). However, the Imedions drop to 1 bar within an hour of sitting idle. With the Eneloops, I can intermittently use the pan and tilt tripod motor for a couple hours, and the 2 bars are still there. I’m guessing the low voltage is why they both start at only 50%. The real capacity shows when there is a load, even at idle, and there, the Imedions are clearly inferior to Eneloop. The Imedions I have show made in Taiwan. The Eneloops, of course, are made in Japan.

  125. Doug
    July 26, 2014

    Very interesting you mention not overheating ENELOOPS I have been using a ENERGISER fast charger Model CH1HR for at least five years with ENELOOPS and they get unbearably hot every time, and the batteries are still in perfect order. Not so with the ENERGISER batteries, I never got past about half a dozen charges before the unit just flashed and refused to charge them

  126. Lawrie Barclay
    January 13, 2015

    Do these batteries suffer from “memory rot” if you do not allow them to fully discharge before recharging. My situation is with cordless phones which after my call. I have been leaving them in the cradle and in less than a year the batteries are not holding their life more than a few minutes of use.

  127. Stefan Vorkoetter
    January 13, 2015

    No, but then neither do NiCd or regular NiMH. What they will suffer from is voltage depression, which is often mistaken for memory effect. This is caused not by failure to fully discharge before charging, but by overcharging. If your batteries are only lasting a year, then your phone cradle is simply overcharging them. The only way to prevent overcharging is to implement a smart charger in the cradle (too expensive for most manufacturers), or to charge at a VERY low current level (takes too long to fully charge a depleted battery then). Having said all that, a good quality battery will probably tolerate this abuse better than the cheap batteries that typically come with cordless phones.

  128. Sean
    February 10, 2016

    Graphs would be much easier to read than a table of numbers.

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