I'm currently using a Wiko Bloom, with Android 4.4.2, using the latest manufacturer update.
A few weeks ago I was trying out the Llama app and after a while I noticed that out of nowhere my battery charge would drop very suddenly to (almost nothing). If I'd see it in time, before it hit 0, then i could recharge it, but often it just depleted completely. This happens in a matter of minutes.
I thought Llama was the culprit, so I did a factory reset, but the problem still persists.
Battery stats reports about 47% phone idle, 46% mobile standby and 7% Wi-Fi.
Battery graph 1 (notice the steep sudden drop of about 45%!), and then Battery graph 2 (again... a steep drop):
I installed GSam to try to get pinpoint on what is causing it, but since I'm not running root, I can't get a full report:
However, in my opinion, this doesn't seem very much out of the ordinary.
I wrote to Wiko and they want me to send in my phone to have it serviced. Before I do that (costs involved, not having my phone, might not be solved, etc.), I wanted to check if maybe there's a wizard here who can help me some more?
I don't have BT turned on, Wifi is on sporadically. Really the only apps I have installed and frequently use are GMail, Google Keep and Firefox.
If I need to go root to figure it out, that's fine; I'll just need help to do it (and to be able to restore it to a pristine state afterwards should it still not work).
Should I need to provide more information, don't hesitate to ask me. In any case, thank you.
Edit (19/07/2015): I have rooted my phone a few weeks ago and installed root version of GSam, together with Wakelock Detector. I believe these report more acurate data on what processes are running and such. I have yet to pinpoint the exact source of the sudden drop in battery level. Screenshots: Graph 3 (from GSam), GSam root, Wakelock Detector (right-click images for larger variants)
I'm still getting a very good number of days out of my battery (mostly because i'm not at all an active user), so no complaints here. But i'm beginning to wonder if the battery perhaps is being misread? That my phone thinks it has more power during the first few days, and then suddenly has to catch up when the voltage dips below a certain point. (The battery is indicated for 3.7V, 2000mAh)