Originally Posted by archer6
A car charger will only shorten the life of the battery if it's left on when the battery is fully charged, or in a hot environment. Some cars electrical systems power the outlet even with the ignition off. Others you must have the ignition on to power the outlet that you plug the charger into. So, if yours is on all the time, and you leave the phone in the car while plugged in it will overcharge the battery. I know this from experience. The combination of BB and wall charger will not. It shuts off at full charge.
As far as letting the battery run all the way down twice when first getting the phone. NO. That was with the old Ni-Cad or NMH batteries. The BB has Li-Ion battery and the best way to use it is to charge it fully then use it until it's down around 15 - 25% range before you recharge it. There are three things to know that affect battery life.
1) Age, the battery begins to deteriorate from the day it's built and stored. even without use.
2) Heat, if left in a hot car or other hot environment this greatly reduces the life.
3) Charge / discharge cycles. The battery is only good for a certain amount of cycles. The amount of cycles depends on the conditions like heat, amount of discharge etc.
Starting with a fully charged battery, you use your BB until the battery it is at 60% and then you charge it, that's one cycle.
From fully charged to 15% then you charge it, that's one cycle.
So the key here is to use it from 100% down to at least 25% or more, then you are getting more run time from the battery, out of each cycle.
Thank you so much for such a great explanation!