For LithIon, there are really 3 things that are bad (That I've heard of): 1) Fully charging them 2) Fully discharging them 3) Heat These are all monitored by

For LithIon, there are really 3 things that are bad (That I've heard of): 1) Fully charging them 2) Fully discharging them 3) Heat These are all monitored by the battery support software/hardware but all will affect performance. The phone will not let charge or discharge to 100% even though it says so. Min/Max values are stored on the phone and adjust as your battery ages. 100%/0% per you phone's display is really just the max/min allowed values.