As already mentioned, you are almost certainly experiencing the effects of RAPID self-discharge problems with your 2500s. These things have been known to go from a full charge to completely dead within 24-48 hours JUST from self-discharge. It has been known to "crop up" as a problem within the first few dozen cycles on these cells, and they just get worse and worse. I completely gave up on mine a long while back.
Another issue worth pointing out is that some cameras are sensitive to voltage input and need a little more oomf on the voltage end of the performance scale to keep that "low battery" indicator from flashing prematurely. Many people will testify that the Sanyo branded ENELOOP Low-Self-Discharge cell performs ADMIRABLY in the voltage department under a load. So while they may be rated for lower mAH capacity, they actually maintain higher voltage under operating loads, which results in them having more true capacity than would be expected based purely on the label capacity. Total energy storage of a cell can be expressed as "watt-hours" which is the combination of the mAH capacity and voltage delivered. Watt-Hours are often a far better comparison of performance from cell to cell when the cells are being used in a device that is "regulated" or requires a certain amount of energy to perform an operation regardless. When the voltage of the battery is higher, the device can draw less amps to achieve the same result.
Following information provided cortesy SilverFox:
link: http://www.candlepowerforums.com/vb/showthread.php?t=79302
Anyways... A NEW energizer 2500 (before developing problems) has about 2.67 watt-hours capacity. The eneloop about 2.32 watt-hours. So even though the label mAH rating is 25% higher on the Energizer, the true energy storage is only about 15% higher.
All this is a totally moot point really when talking about the energizer 2500s, because by the time you use them, even if it's only been a few hours since the charge, they are very likely already depleted to a capacity lower than that of an eneloop. The eneloop will hold a charge for a LONG time. IIRC it's like 80% after a year. (can't remember exact figure).
Another great thing about the eneloops, is that they seem to be VERY robust cells as far their life expectancy is concerned. Like I said before, the energizers seem to only last a few dozen cycles before having major problems. Eneloops on the other hand, seem to be good for several hundred cycles or better. I think they are rated at like 1000 cycles by the manufacture, but I think that would depend on usage habits etc etc... I've personally been abusing the living heck out of eneloops in various 4-6 amp loads, and every single cell I bought is still performing flawlessly.
Eric
