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Customer Review

1,901 of 1,927 people found the following review helpful
5.0 out of 5 stars Some new facts about LSD cells you should know..., January 6, 2007
This review is from: Sanyo Eneloop AA NiMH Pre-Charged Rechargeable Batteries - 4 Pack (Discontinued by Manufacturer) (Electronics)
[Updated Oct 24, 2008]
My original review on the Sanyo eneloop NiMH cells was written nearly two years ago. Since then, I have learned a lot more about the characteristics about eneloop and other low-self-discharge cells. So it is time to clear up some inaccurate information I wrote about eneloop's self-discharge rate.

1. I was told that the Sanyo eneloop cells were not 100% fully charged when they leave factory. This makes sense because new cells are fast-charged in the factory to save time. In order to avoid problem with heat and gas built-up, they cannot be charged to 100%. I have tested some eneloop cells that were manufactured 20 months ago, and they still maintained about 70% charge. On the other hand, cells manufactured 6 months ago contain about 75% charge. This confirmed that the discharge rate is much lower than I previously estimated.

2. The self-discharge rate of eneloop (and other LSD cells) is not linear! My own testing showed that a fully charged eneloop may lose 10% of its initial charge during the first month of storage, but in the second months it may lose just 2-3%. The rate becomes even slower after three months. In fact, my 5-month self-discharge test using various brands of LSD cells gave nearly identical results as my previous 3-month test.

3. When an eneloop cell is freshly charged, its capacity actually measures at about 5% higher than its rated capacity (2100mAh vs. 2000mAh). In my previous tests, I used measured capacity as base to calculate the percentage loss. This results in apparently higher percentage loss. Had I used the rated capacity as base value, the self-discharge rate would be about 5% lower.

Based on the above revelation, I believe Sanyo's claim about eneloop (maintain 85% charge after one year, 80% after two year) to be accurate. Therefore the title of my previous review ("The News of LSD Has Been Slightly Exaggerated") has to be replaced.

Over the past two years, I have tested several different brands of LSD cells available from Amazon.com, including Rayovac Hybrid, Kodak Pre-Charged, and Duracell Pre Charged. They have all performed very well - practically no difference from the Sanyo eneloop. So the bottom line is: just pick which ever brand of LSD cell is on sale, and you can't go wrong.

[Update on April 21, 2011]
- After testing and using various brands of LSD cells over the past four years, Sanyo eneloop cells have proven to be the most reliable and consistent of them all. I now have to recommend Sanyo eneloop over all others brands.

- Recently Amazon started to offer the SANYO NEW 1500 eneloop cells, at around 25% higher price. In my testing, the improvement of the new eneloop over the original is hardly noticeable. So you'll have to decide whether it is worthwhile to pay the extra cost.
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Comments

Tracked by 24 customers

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Showing 1-10 of 212 posts in this discussion
Initial post: Mar 26, 2007 1:43:42 PM PDT
SInce you're an engineer, I wanted your opinion on whether a non-eneloop NiMH charger
could re-charge these batteries.

Thank you!

In reply to an earlier post on Mar 26, 2007 5:37:02 PM PDT
According to press release by Sanyo, eneloop cells can be recharged using any quality ('smart') NiMH charger. I have been charging all my Sanyo eneloop (and also Rayovac Hybrid) cells using the LaCrosse BC-900.

In reply to an earlier post on Apr 2, 2007 11:02:39 PM PDT
Thank you very much for your reply!

Posted on Apr 21, 2007 7:09:55 AM PDT
Thanks for reporting on this product with such detailed information. I also noticed that my Eneloop were performing only marginally better than old-generation 2000mAh cells, as you wrote. You should share your results with ConsumerReports.com!

In reply to an earlier post on Apr 21, 2007 12:16:45 PM PDT
Last edited by the author on Apr 21, 2007 12:24:23 PM PDT
Four or five years ago, when most NiMH AA cells were below 2000mAh, I don't have problems with self-discharge rate. I used those old-generation rechargeable batteries in wall clocks, remote controls and calculators before, and they can often last for over 6 months. Only in the last 2-3 years, when capacities of new NiMH AA cells reached 2500mAh, people started to notice the problem with rapid self-discharge.

Basically, battery manufactures scarified self-discharge rate in favor of higher capacity. That's why most newer (2500-2700mAh) NiMH batteries will self-discharge completely within a few weeks.

I have a sneaky feeling that the latest generation of "low self-discharge" NiMH cells are just repackaging of 5-year old technology with creative marketing campaign. Let's hope I'm just being too cynical.

Posted on Apr 24, 2007 4:41:50 PM PDT
This IS a very informative post. I was not able to follow all of the technicals but could you recommend the best double a batteries (rechargeables) for a digital camera?

In reply to an earlier post on Apr 24, 2007 9:20:41 PM PDT
I reccommend either Rayovac Hybrid or Sanyo eneloop AA cells. I'm using both brands for my digital cameras and flash unit. Eneloop looks cooler, but Hydrid is a better value (since you can get 4 AA for under ten dollars from Walmart or Target).

Based on personal experience, I don't trust those 2500mAh cells (no matter what brand) due to their rapid self-discharge problem. Some people may say: "Just make sure you recharge all your cells the night before". But to me, the peace of mind that comes from using low self-discharge battery is more important.

Come to think of it, for my next photo trip I have to bring at least 18 rechargeable AA cells for all my equipment. Try charging that many cells the night before!

In reply to an earlier post on Apr 26, 2007 9:50:32 PM PDT
Thanks! You also mentioned something about the Kodak low self discharge (available at Walmart) how do they stack up to these two types?

In reply to an earlier post on Apr 27, 2007 7:41:20 AM PDT
Last edited by the author on Apr 27, 2007 7:45:08 AM PDT
I don't think Kodak actually manufacture any rechargeable batteries. So those Kodak Pre-Charged batteries are very likely to be re-labeled Rayovac Hybrid. Their packagings make exactly the same claim ("Stay charged up to 4x longer"), and they have the same capacity (2100mAh).

If my suspicion (about low self-discharge being 5-year-old technology) is correct, then any battery manufacturer can just fall back to their 2000mAh cell designs, and sell them as new LSD or "Pre-Charged" batteries.

Juicy conspiracy theory in the making?

In reply to an earlier post on Apr 27, 2007 12:22:57 PM PDT
Interesting thought. Can you give me some more details on your theory? Also how significant is the difference between the 2000mAh and the 2100mAh? As far as the Kodaks are concerned I think that they are made in Japan NOT China so I don't believe that they are made by Rayovac but I'm not sure what I saw regarding their manufacture origin. I actually had a similar suspicion - that these were rebranded Enelopes but then the origin (Japan) AND the 2100mAh as opposed to the 2000mAh threw me off. Maybe there is another producer out there and just taking the old technology batteries and repackaging for Kodak.)
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