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(More customer reviews)The package of this product (UltraLast Green High Power/Capacity NiMH 8-Pack AA) proudly advertises "LASTS Up To 3 YEARS". This sounds really amazing, because even SANYO eneloop Pre-Charged Rechargeable Batteries can only claim 2 years of storage life (the actual claim is "retain about 80% of energy after 2 years of storage at 20 degree C"). That's why I wanted to try those UltraLast cells, even though they are priced higher than most other pre-charged batteries.
When I received those UltraLast cells, I was shocked to find out that they are all completely discharged (terminal voltage 0.6-0.7V). This has never happened with any low-self-discharge cells I have tested. So I visited 'ultralastgreen dot com' to search for more information. As it turns out, the actual claim on the web site is:
"Can be charged as many as 500 times, or up to three years."
In other words, it means that those cells have a service life of up to three years (which sounds ridiculously short to me). It does NOT mean that they can retain charge for up to three years. Based on my initial observation, those cells are probably suffering from rapid self-discharge problem, just like all other ordinary NiMH cells with capacity 2500mAh or over.
Although one can argue that the product description didn't actually say 'Pre Charged' or 'Low Self Discharge', that still leaves the claim of 'High Power/Capacity'. Those UltraLast cells are rated for only 2400mAh, which is much lower than today's high capacity NiMH cells (typically 2700mAh or more). Actual measurement on my La Crosse BC-900 showed much worse results: two out of four cells tested were initially under 1000mAh. After several deep discharge/recharge cycles, three cells reached 2300mAh, while the fourth one remains stuck at 1100mAh.
Basically, those UltraLast Green 'High Power/Capacity' cells are just ordinary rechargeable NiMH cells with nothing special to offer. Yet they are being sold at a premium price under misleading claims. My purchase turns out to be a complete waste of time and money. Hopefully, you who read this will take my gentle advice: avoid this piece of junk!
[Update on Apr 9, 2010]
The lowest-performing cell finally reached 2100mAh after four or five discharge/recharge cycles. So for that I bumped the rating up one notch.
[Update on Aug 21, 2010]
Long term storage test data: After three months sitting on the shelf, the average remaining charge of those Ultralast Green 'High Power' cells is just 49%. This is similar to the self-discharge rate for ordinary NiMH cells.
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High Capacity AA Batteries Ideal for Cameras and Flash. 2400mAh Minimum Capacity.
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