battery - Are there rechargeable batteries which don't discharge when idle?

This is kind of a peripheral question — not exactly about photography, but about the batteries for my camera, which uses AA batteries.

I have tried every known brand (to me) of rechargeable battery, and I find that no matter what brand, the batteries discharge when left idle for more than a day or two, whether in the camera or out. This is tremendously frustrating to me, because every time I pick up my camera to take a spontaneous shot, I see that the batteries are flat — so I waste a minute changing the batteries... only to find that the spares are also flat... this despite the fact that I had them in the &$*&! charger for about 36 hours straight just three days before!

Does anyone else have this problem, or is there some charge-eating poltergeist inhabiting my home? Is there some brand or type of rechargeable AA battery that actually keeps its charge for a reasonable amount of time?

Answer

I have conducted quite a lot of testing to find out how the low self-discharge cells keep their charge. You can see the results here.

Sanyo claims the self-discharge pattern follows inverse S curve, meaning that you lose first some 10-20% rapidly in first 1-2 weeks or so, and then it levels, and the batteries retain some 70-75% of charge after one year. My tests this far span only to 2 months, but this far it would look like Sanyo was correct.

I am hesitant to mention any brands, but if you really want some, Sanyo Eneloop XX and Ansmann maxE seem to offer more actual capacity (after some time in storage) than the rest, while Varta Ready2Use performs worse than the rest. The rest, Sanyo basic Eneloop, Maha Imedion, GP ReCyKo and Sony CycleEnergy are pretty much even. In practice the differences are smallish, so any LSD battery, with possible exception of Varta, will work, and work a lot better than regular NiMH batteries if there is more than 1-5 weeks between last recharge and usage.

Here is another study, comparing Sanyo basic Eneloop and regular higher-capacity NiMH batteries. With these two brands the basic Eneloop wins in actual capacity after 3-4 weeks of storage. However, basic Eneloop was the very first product to hit LSD market, and the capacity is a bit low by today's standards, so for example Eneloop XX would win already after 1-3 weeks.

(I'm not affiliated with any of the included brands, I'm just a fellow amateur photographer who wanted to know which cells exactly are worth buying.)

If you need to store batteries for extended periods before using, you can also wrap them to watertight bag and put them to freezer. The lower temperature will slow down self-discharge.

I also have anecdotal data on this: For example, I had matched set of six ReCyKo/Eneloop batteries 2-3 months in my camera bag and then I switched them to use in my Canon 450D, and shot some 400-600 images before they depleted. Fresh batteries would do more, but still, that's a lot better than old-style NiMH would do.