Currently Being ModeratedSep 6, 2011 2:52 PM (in response to michelle126)
It is impossible to close all applications. Even if you kill then in the Recently Used ribbon some applications will respawn and run hidden in background. This includes the built in applications and any that have Notifications enabled.
Do you have any Push email accounts? If so delete them, reboot the phone, and add them back.
Is cellular data on? If it isn't turn it on, and turn on 3G if it is off. Sometimes data gets "stuck" in a queue and the phone keeps retrying to send it.
Likewise, turn on WiFi, because it only uses power when the phone is awake, and then it uses about 1/10 the power of 3G.
Currently Being ModeratedJan 16, 2013 10:14 PM (in response to michelle126)
I had exact same symptoms on an iphone 4. Try this:
double-press home button to bring up multitasking bar
Kill all running apps (tap and hold till you get the red minus)
Worked for me. Probably I had a runaway app chewing up CPU constantly.