This depends on who you ask. Alot of people will say different things.

Generally, to the best of my knowledge, your best bet is not to charge it every night. Charging kills battery cells, the more often you charge it, the faster it will die.

I've tried this myself as I used to charge my phone every night. I got a new battery and now I only charge it when I need to (once every 4 days or so) and the battery life has held up better then my last battery.

I charge my battery every night never had an issue doing so. The 325 has a good battery life but I talk a fair amount daily and don't feel comfortable skipping a night. I do let it drain down completely from time to time.

The old nickle cad batteries had to be completely drained and then recharged or they would develop a "memory" and you would literally lose part of the battery. With Lithium Ions they can be recharged whenever and never develop a "memory", meaning you will still have the full battery even if you discharged it halfway and then recharged. The downside to LiIon batteries is that they have a limited lifespan of "charge cycles". A charge cycle is when you charge the battery. So if you are charging the battery every night and you could get three days out of the battery before it really needed to be recharged, then you are shortening the life of the battery.

Hope that helped..