I have JXD s7100B with Android 2.3.4. After rooting it and killing cell apps (and all unnecessary apps) it's battery lasted about 4 hours and it was OK. I used Battery Calibration from Google Play to try and get some more and after that it started acting weird: It could not boot (it would loop the bott screen) unless it's on the charger. After it boots it would drain the battery in less than 20 minutes! When I try to charge it it would charge to full in 10-15 minutes but when I disconect the chatrger, it will again last <20min.
After a few days it started acting normaly (booting and battery life) but few days after that it started the same again: cannot boot unless on charger and lasts <20min. I tried recalibrating battery again with Battery Calibration, reflashing firmware with custom rom and with original rom from the manifacturer, doing factory reset from the recovery mode and then installing stock chinese ROM - nothing. It still acts the same. I also used an app to see if something is draining the battery but nothing works wore than 20 sec in all the taime that battery lasts.
Once, while using bitrider's custom rom, I booted it and got black screen with no icons nor drawer (i guess launcher crashed) but with only the notification bar (battery level notification, working clock) and touch screen not working. I left it like that to see how the battery will work and it lasted normaly! After that I experimented with two original firmwares from the manifacturer and it drained battery fast like before. If I start JXD in restore mode battery lasts long there too.
So my guess is that battery is OK but software somewhere in Android is reading baterry level of 100% as 100% but of 97-98% as 15% and it forces power off although battery has juice to power the tablet. Is there an app that can tell to Android how to see battery or could I do it by editing the firmware somehow. Anything to make it work like it did.
Also can someone make dump of the original chinese firmware because I have a feeling that some partitions are not wiped with factory reset so I can push that part from outside. Two guys on apad forum also have this problem and it would help a lot.