Powerex MHRAAI4 Imedion AA 2400mAh 4-Pack Rechargeable Batteries

Ordinary 'high-capacity' NiMH cells typically advertise charge capacity of 2500-2700mAh (for AA), but they all suffer from rapid self discharge problems. That is why I switched over to low-self-discharge (also called 'Pre-Charged') rechargeable batteries more than six years ago, starting from the original  SANYO eneloop . Over the years I have tested many other name-brand LSD cells such as  Rayovac Hybrid  and  Kodak Pre-Charged , all with great results.The only drawback of LSD cells is lower capacity. First-generation LSD cells are typically rated at 2000-2100mAh. But by now, we have seen arrival of second-generation LSD cells with higher capacity, such as this  PowerEx Imedion Precharged 2400mAh AA Rechargeable Battery . Here are my test results, using the  La Crosse BC-900  battery Charger/Analyzer:- Right out the package, the average remaining charge is 1880mAh for a set of four Imedion AA cells. This is about 78% of the rated capacity, which suggests those are low-self-discharge type (ordinary NiMH cells typically arrive exhausted)- After just one Charge/Discharge cycle, the average capacity improved to 2455mAh, or 2% higher than rated capacity. This number remains the same in subsequence cycles. Again, this performance suggests that those cells are LSD type (ordinary NiMH cells typically takes ~5 cycles to slowly approach their rated capacities)Just for comparison, here are my measured capacity numbers for other brands of LSD cells:-  Sanyo Eneloop XX : Rated 2500mAh, measured ~2600mAh (4% higher)-  Yuasa Enitime PLUS : Rated 2500mAh, measured ~2400mAh (4% LOWER)-  GP Recyko NiMH AA : Rated 2100mAh, tested ~2230mAh (6% higher)-  SANYO eneloop (2nd-gen) : Rated 2000mAh, measured ~2130mAh (6% higher)About long-term self-discharge rate: I tested a pair of Imedion AA after 5 months in storage. The average remaining charge is 2125mAh, or 86% of the original capacity. A second pair was tested after 17 months, and retained 75% of original capacity. That means the Imedion's self-discharge rate is just slightly faster than that of Sanyo eneloop, but similar to that of the Sanyo XX. For all practical purposes all three are sufficient.[Conclusion]:The measured capacity of IMEDION AA cells (2455mAh) is higher than all others except for Sanyo XX (2600mAh). However, as of this writing, the Sanyo XX costs about 50% more than the Imedion. That makes Imedion LSD cells a much better deal compared to Sanyo XX.[Important note]:The Imedion AA cells are quite a bit thicker than normal alkaline cells. So they may not fit in appliances with tight battery compartments. This is actually a common problem with high-capacity NiMH cells. I don't have a pair of calipers to measure the cell diameters. But in term of relative 'fatness' of various AA cells, I can arrange them in the following order:IMEDION > Sanyo XX > Sanyo eneloop > Rayovac Hybrid > Alkaline

Ordinary 'high-capacity' NiMH cells typically advertise charge capacity of 2500-2700mAh (for AA), but they all suffer from rapid self discharge problems. That is why I switched over to low-self-discharge (also called 'Pre-Charged') rechargeable batteries more than four years ago, starting from the original  SANYO eneloop . Over the years I have tested many other name-brand LSD cells such as  Rayovac Hybrid  and  Kodak Pre-Charged , all with great results.The only drawback of LSD cells is lower capacity. First-generation LSD cells are typically rated at 2000-2100mAh. Recently, I have seen arrival of second-generation LSD cells with higher capacity, such as these  IMEDION AA 2400 mAh low self-discharge batteries . Here are my test results, using the  La Crosse BC-900 battery Charger/Analyzer :- Right out the package, the average remaining charge is 1880mAh for a set of four Imedion AA cells. This is about 78% of the rated capacity, which suggests those are indeed low-self-discharge type (ordinary NiMH cells typically arrive exhausted)- After just one Charge/Discharge cycle, the average capacity improved to 2455mAh, or 2% higher than rated capacity. This number remains the same in subsequence cycles. Again, this performance suggests that those cells are LSD type (ordinary NiMH cells typically takes ~5 cycles to slowly approach their rated capacities)Just for comparison, here are my test results for other brands of LSD cells:-  Sanyo Eneloop XX : Rated 2500mAh, measured ~2600mAh (4% higher)-  Yuasa Enitime PLUS : Rated 2500mAh, measured ~2400mAh (4% LOWER)-  Lenmar R2G AA : Rated 2150mAh, tested ~2030mAh (6% LOWER)-  GP Recyko NiMH AA : Rated 2100mAh, tested ~2230mAh (6% higher)-  UltraLast Green Everyday Precharged : Rated 2100mAh, measured ~2200mAh (5% higher)- SANYO eneloop (2nd-gen): Rated 2000mAh, measured ~2130mAh (6% higher)The measured capacity of IMEDION AA cells (2455mAh) is higher than all others except for Sanyo XX (2600mAh). However, as of this writing, the Sanyo XX costs nearly twice as much as the Imedion. That makes those Imedion LSD cells a much better deal compared to Sanyo XX. When comparing Imedion to Sanyo eneloop, you pay ~15% more for ~15% increase in capacity. So again, this makes the Imedion a great deal.One important side note: The Imedion AA cell is quite a bit thicker than normal alkaline cells. So they may not fit in appliances with tight battery compartments. This is actually a common problem with high-capacity NiMH cells. I don't have a pair of calipers to measure the cell diameters. But in term of relative 'fatness' of various AA cells, I can arrange them in the following order:IMEDION > Sanyo XX > Sanyo eneloop > Rayovac Hybrid > Alkaline[Update on Oct 23, 2011]Tested a pair of Imedion AA after 5 months in storage. The average remaining charge is 2125mAh, or 86% of the original capacity (2470mAh). This charge retention rate is almost as good as that of Sanyo eneloop.[Update on Mar 31, 2013]Tested a second pair of Imedion AA after 17 months in storage. They retained 75% of original charge. This means the Imedion's self-discharge rate is just slightly faster than that of eneloop. For all practical purposes both are excellent.

These batteries are the best rechargeable batteries on the market today, I have tried many different ones over the years, and these are the first I have come across that hold their charge over extended periods of time, generally I use them for a camera flash and they get hammered for a couple of weeks of constant use, but then might not be used again for weeks or even months sometimes, but when I come back to them, they are ready to go.

I've been using the POWEREX 2700mAh in my flash guns (Cactus RF60's) which have never let me down, got these IMEDION's for use in the Cactus V6 transceiver which doesn't require power but needs to be ready at all times. Having said that, 2400mAh is still big power with the added ability to stay charged over long idle periods... Totally recommend these and it was a very good price from Amazon.

The problem with batteries for flash guns is that you have to remember to recharge them before you use them. These batteries solve that problem, although they have a slightly lower capacity. They come with a handy case to keep them together and stop them from scattering in my camera bag.

These are absolutely excellent, dependable, high-capacity batteries. I use them in my Canon 600EX flashgun and they are perfect, lasting an exceptional time until they need to be replaced, and working fine if left in the flash for some time.

Good quality batteries, so far I have used them for several times, with no loss of charge. I haven't left them for a long period [over a month].