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(More customer reviews)[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.
Click Here to see more reviews about: Sanyo Eneloop 8 Pack AA NiMH Pre-Charged Rechargeable Batteries
From the Manufacturer Why Sanyo eneloop? Sanyo eneloop rechargeables can replace an entire kitchen drawer's worth of dry cell batteries You already know the benefits of using conventional rechargeable batteries. But Sanyo eneloop batteries have advantages over other rechargeables that put them a step ahead. Sanyo eneloop batteries are an excellent choice for your rechargeables because: * They can be used right after purchase * They consistenly yield high performance * They have a long shelf life with no loss of energy * They can be used everywhere * They are environmental friendly Self-Discharge: Why Conventional Rechargeables Don't Cut It Conventional rechargeable batteries have numerous advantages that make them great to use for your portable electronics. But they also come with certain disadvantages. After purchase, rechargeable batteries have to be charged before they can be used. And once charged, rechargeable batteries lose the stored energy rather fast. The charging takes quite long and rapid chargers are expensive. Not only that, but continuous charging or frequent charge to "top off" the lost energy (without complete discharge) can destroy the battery. All these negative attributes have one root-cause: self discharge. Self-discharge means that a charged battery slowly discharges itself without any equipment consuming any current. This is the reason for rechargeable batteries being sold in a discharged state. And this is the reason that keeping charged batteries for some time did not make any sense. When you needed them, the energy was gone. Sanyo eneloop batteries have an extremely low rate of self-discharge, which means they hold their stored energy for a very long time--charge your batteries once and put them in your kitchen drawer, and over a year from now you'll still be able to use them right away, without needing to charge them again.
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