Originally Posted by HarryT
A friend of mine has just upgraded his Galaxy Note to ICS (the official Samsung upgrade) and it's absolutely destroyed the battery life. Previously he was getting a couple of days' usage from a battery charge; after the upgrade it's draining the battery flat in a few hours.
I'm no Android expert but I know that many people on this forum are. Can anyone offer any advice on what he could do to resolve the problem?
I can't see the same problem on my Note after upgrading do ICS, but from other forums it seems there are several possible reasons:
* different battery calibration (ICS doesn't inherit the previous battery calibration data). This should clear after a couple of full charge/discharge cycles
* not wiping the device or not clearing the cache after the upgrade (but I did not wipe it and still don't have this problem)
* incompatible app. You can look at the battery usage under settings and check if some app is using more power than it reasonably should.
* smartphone constantly looking for WiFi or 3G networks - changing the network settings should solve that problem (eg. under WiFi -> advanced it is possible to switch off the "keep WiFi on while asleep" option)
* device not switching into lower processor speed when idle, which can have several reasons. One of these seems to be connecting/disconnecting the charger while the screen is off (which could cause the Note to mistakenly recognize the connected/disconnected state)