Originally posted by Philoslothical It's much healthier for the battery to top it off when it's still at 90% than it is to let it get to 10%.
Wow. I didn't know that. In fact, I had assumed something close to the opposite was true -- what happened to the "memory effect" with rechargeable batteries that people used to talk about? I had always thought it was best practice to periodically drain a battery completely, because if you started recharging too soon, the battery would "remember" the amount of new charge it was obtaining as if that percentage represented the whole capacity of the battery, thus depleting the total storage capacity. Is that no longer true? Was it ever?
Also, in regard to the battery charger that comes with the K-5, I saw a thread here recently claiming that over-charging the battery could contribute to the mirror flop issue...
One thing that makes this tricky is of course that the battery indicator is pretty much useless; it'll seem to show a full charge, then suddenly you're nearly out of juice.
EDIT: Ok, I see I was r(mis)emembering a purported phenomenon with ni-cad batteries, not all rechargeables:
http://en.wikipedia.org/wiki/Memory_effect
But note this passage from that article:
Temporary effectsVoltage depression due to long-term over-charging A common process often ascribed to memory effect is voltage depression. In this case the peak voltage of the battery drops more quickly than normal as it is used, even though the total energy remains almost the same. In modern electronic equipment that monitors the voltage to indicate battery charge, the battery appears to be draining very quickly. To the user it appears the battery is not holding its full charge, which seems similar to memory effect. This is a common problem with high-load devices such as digital cameras. Voltage depression is caused by repeated over-charging of a battery, which causes the formation of small crystals of electrolyte on the plates. These can clog the plates, increasing resistance and lowering the voltage of some individual cells in the battery. This causes the battery as a whole to seem to discharge rapidly as those individual cells discharge quickly and the voltage of the battery as a whole suddenly falls. This effect is very common, as consumer trickle chargers typically overcharge.
Sounds to me like overcharging could cause more problems than undercharging... ?