When to charge bats?

[OnnaB]

m now confused. I have an original Tornado, 650 maH. Should I keep using the batteries until the light blinks, indicating it's dead? Or, should I use several hours, then change to the next bat BEFORE the bat dies? They are a bit pricey, and I would like to get the most use from them.
Thanks!

 

[ScatRD]

The Tornado has a limiting switch built in so it cuts off before the battery is damaged. Just use it until the led starts blinking then move to the next one. I usually let them sit for an hour or so in the discharge state before I put them on the charger.
It probably won't make much difference in the long run but I feel better making sure the battery's internal temp and chemistry is stable before putting it on the charger. I might get an extra week or 2 out of a battery but considering they should get over 1000 cycles I don't see it amounting to much.

 

[Kent C]

How to Prolong Lithium-based Batteries - Battery University

"Similar to a mechanical device that wears out faster with heavy use, so also does the depth of discharge (DoD) determine the cycle count. The smaller the depth of discharge, the longer the battery will last. If at all possible, avoid frequent full discharges and charge more often between uses. If full discharges cannot be avoided, try utilizing a larger battery. Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles other than to calibrate the fuel gauge on a smart battery."

Scat's trick of letting it cool off first is also good:

"Specifying battery life by the number of discharge cycles is not complete by itself; equally if not more important are temperature conditions and charging voltages. Lithium-ion suffers stress when exposed to heat and kept at a high charge voltage."