One thing you might want to try is to disable the phone to hunt for 3G. I haven't tested the difference as I did it the 2nd day I got the phone. Settings->Phone mode: dual mode IS GREYED out. Cannot change this setting I had to put in a tmobile SIM to be able to change this setting to GSM. And once you put back at&t SIM, this setting remains fixed to GSM. I have no idea if it will make difference to battery (it should if n900 is constantly searching for 3G) but I doubt n900 is smart enough to not hunt for 3G if your network is not. Please report if your battery improved with this method