| | 11-18-2012, 10:33 PM #1
I have two Lumia 920s, one black, one red for my GF. Both are charged by the wireless charger, both are running AT&T LTE with similar apps installed. I charge them daily overnight, practically at the same time.
On the black lumia, after a day of light usage (pretty much all emails), the battery would have >80% remaining, and the "estimate remaining time" would show something like 2 days.
On the red one, it'll come home with 40% remaining, and if I don't charge it immediately, it'll run out of battery in 2 hours. I also notice that simply putting the phone of the desk without ANY usage, it'll warm up near the top of the phone, indicating some sort of power drain.
Yesterday I've decided to get to the bottom of this. So I begun with the red lumia at 40% power, turn on airplane mode, kill all background apps (at that time, only Weather Channel and Evernote), and just let the phone sit for 2 hours. After which I came back and found the phone still at 40% and with a cool back. This tells me that one of the action I took eliminated the power drain. So I begun turning things on one by one (only keep one potential source on), then wait for an hour and see what happens.
I've tried Bluetooth, NFC, WIFI, Cell with no data, and cell with data. Interestingly, when I left turned the cell radio on, the phone shows the most significant drain in that hour. This is with no background task running, and no LTE data connection - ONLY the phone radio is on.
I was really lead to believe that the red unit is defective, and was going to return it. Out of curiosity I power cycled the device (Vol Down and Power together for 10s) just to see what happens. Strangely, after the device reboots, I can no longer reproduce the drainage. Today I turned everything back on, and after 7 hours of light usage (web and email only), it's showing 95% battery left. The estimate time remaining is...7 DAYS 10 HOURS ?!?
So needless to say I won't be returning it anymore. This left me wondering was it the soft reset that cured the problem, or was it something else? I won't be able to find out myself as it no longer repros for me. I hope someone else on this forum that has similar problems can try this method and report back what your findings are. The thing to try are basically:
1. identify the source of your battery drain by turning on airplane mode, and kill all background tasks
2. soft reset by holding vol down + power button. Note: your data and settings will remain, this is only rebooting phone.
Today on the red lumia the same problem occurred again. By the time I went home the battery had only 50% left, and the estimate time shows 3 hours. Again the phone would be warm even in standby, so I've powered it off, and restarted. Now it's got 30% of battery and 14 hours of estimated time - so resetting the phone does cure the drain.
This leaves me to believe that there are some app/background task/os task that was not properly shutoff. I'm thinking either Weather Channel or Bluetooth pairing with car radio. Tomorrow I'm going to run it with bluetooth completely shutoff, and see if the program persists.
Just a side note: the phone, when in standby, gets warm near the top left corner. Anybody know what's in that corner?