Like most people I know, I own way too many battery-powered electronic devices. My photography habit is only making the matter worse, since I have a ton of equipment that is powered by AA batteries. Many pros will use nickel-metal hydride (NiMH) batteries because their high capacity and low internal resistance are good characteristics for many photography applications, most notably, powering flash units.
The trouble with NiMH batteries is that they self-discharge rapidly, about 1-2% per day. If you charge up a set and leave them alone for a month, they’ll be almost flat. Photo pros don’t have a problem with this, since many of them shoot in high enough volumes that it’s not a big inconvenience to keep charging them since their usage runs way ahead of the self-discharge.
For the rest of us photographers, it is a major annoyance. It also prevents batteries from being used in some attractive applications, like remote controls. Remotes don’t draw a lot of power, but the self-discharge will make rechargeables run flat far too quickly to be used.
Fortunately, Sanyo may have come to the rescue with their new eneloop batteries. They’re lower capacity than most NiMH batteries, but Sanyo claims they don’t self-discharge. I haven’t done any quantitative testing, but my personal experience so far is that the claim is not completely farfetched. I bought a set of AAs and popped them into my flash on July 19. I’m still shooting with them, so even a month after installation they still have something.
(Sanyo claims that they retain 90% of their charge after 6 months, 85% after a year, and 70% at two years, but I have not attempted to verify those figures. Sanyo ships them charged and says they can be used immediately on receipt, which certainly is true.)
The next qualitative test is with the set of AAAs that arrived on Friday. On Sunday the 19th, I installed them into my Logitech Harmony remote. I’ll report back when I need to recharge them.