Originally Posted by
unterhausen
the data I have seen for lithium-ion shows that frequent deep discharges can reduce the lifetime of a cell by more than a factor of 10. I probably could find similar data for lithium-polymer, but I haven't looked. I expect it to be similar. Hybrid cars keep the charge level in a very limited band, deep discharge is bad for most battery chemistries
Generally, the circuitry that controls the charging/discharging protects the cells from damage (or at least it should). The real damage to Li-ion/Li-Polymer batteries is the number of charges, charging too long if the charger is crappy, and - the worst - age. These chemistries just only last so long from the day they are manufactured. The clock starts ticking right away.
J.