I've been using j020c k100 since it was released and i haven't had a wlod and just some reboots when the bat is low. Battery life is very good, i just took some screens to show you:
Today I were listening to music over bluetooth with parrot(about 1h30), wi-fi at university, played games, I made calls, sms, installed apps, 2g on, wifi always on so as bluetooth and gps, weather widget updating every 2 hours, screen light at 50%.
I think this version is very good.
Thank's J for all your and the team work.