Except that 15 minute NiMH chargers abuse the cells, leading to capacity loss and premature failure. An hour is the shortest charge cycle that doesn’t damage the cells. If you’re interested in such things, there has been EXHAUSTIVE discussion of batteries over at CandlePowerForums.com - though as you might imagine, predominantly in the context of flashlights and other lighting devices.
My charger happens to be a half hour one. Rotating through the same 2 pairs of AA in my camera, maybe weekly charging, I had the first cell go bad after 4 years. My kid’s AAA’s lasted nearly 2 years of being run down to zero in her DAP before swapping, charging a couple times/week (they still worked, but around half capacity) Both sizes got better life than most Li batteries I’ve used.
Different brands of cells can be designed so they can or can’t take fast charging as well. From reading some of the ad copy, there’s also some spin going on by MFR’s that don’t make fast smart chargers (or good fast charging batteries) to make their own gear look better.
I’ve been in some groups dealing with lighting (on bikes) and they often run them until the light is too dim to use which is hard on batteries, since a slight mismatch in cells will lead to some getting reverse charge. Electronic gear usually cuts you off when the voltage reaches some still safe level.
Message Edited by donp on 01-09-2010 09:06 AM