On Wed, Dec 15, 2010 at 1:40 AM, John Gardner wrote: > N cells in series are unlikely to run out of chg at the same time. > Provided the load continues to try to draw current, whichever cell > runs out of gas 1st will be reverse-charged by the others. To it's > considerable detriment. > > There are various schemes to prevent this from happening. Mine > lacks subtlety, but has the virtue of being (relatively) GI-proof. > > I've already thought of a protection mechanism for that. I'm not letting th= e pack discharge to less than 4.4 volts (so 1.1 volts per cell). I know for sure that my cells are almost perfectly balanced, so they will never discharge below my safe limit. 1.1 volts per cell is also a good level to prevent capacity degradation. I'll set the voltage reference via resistor divider from the switching supply. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .