Try this: Test scenario #1 - Charge the battery fully - Start playing your music and let it play all night - Notice how less the battery depletes by morning. Test scenario #2: - Charge the battery fully - Switch on GPRS/WiFi and keep it on all night - Battery will be fully drained by morning and phone will be switched off. From the above test scenarios, I'm surprised to see that playing music all night has not much affect on the battery life, rather GPRS/WiFi has a more adverse affect. I guess this should be the other way round.