1. AC Question's Avatar
    I've acquired an ancient Samsung Young 2 (SM-G130HN) running KitKat 4.4.2. Battery never seemed to last more than a few hours (four if lucky), despite turning off all the usual suspects - Sync, Location, NFC, Bluetooth, email pull once every few hours, etc.

    Eventually rooted it and uninstalled bloatware, installed a battery monitoring/saving app and now I can at least get over 18 hours out of it when on standby and pretty much not being touched. Sometimes almost two days. Not a big user, it's just a fallback phone to play with ;-)

    I've noticed that most times it drains massively when it reaches about 40%. It'll creep down a few percent an hour under light/moderate usage, maybe lose 10% when left on overnight for the first night. By the second night it'd be on about 40-44% before I went to bed, and by the time I awoke, it'll either be showing around 20% and when I tap in the lock code, it'll immediately drop to 2% and kick up a battery warning. Or it'll be dead already and require a charge.

    Thought it might be the battery -- like a cell gone bad or something -- so I bought a new one. But it does exactly the same kind of thing. Been trawling forums on sudden battery drain / stuck apps etc and trying all the tips and tricks I can find, to no avail.

    Anyway, the phone's unlocked. Today it was showing 46% battery. I turned it off, swapped SIM, turned it back on again and the meter showed 28%. What?! Topped up SIM card, battery showed 27%. I turned it off, put the old SIM back in, powered it on. Battery showed 19%!

    Just for the sake of -- uhhh, something, in case turning it on and off was killing the battery -- I powered it off and swapped SIM again. Battery only dropped to 18%. Cycled power again: 17%. Used it for a couple of minutes to read a text message and check the battery usage in Settings. It seemed alright for a few minutes, then dropped from 15% to 3% and I got a battery critical warning.

    I understand the meter isn't super accurate, but this is ridiculous! Something's either misrepresenting the amount of juice left, or KitKat itself (or some app) is chomping through it quick-smart. As I say, it's a brand new battery, so it ain't too many charge cycles affecting its life. Anyone any experience in this? Anything else I can try? Could it be hardware related?

    Battery usage monitor shows that two-thirds of the usage is split between Device Idle, Android OS, Cell standby and Android system, with the remainder being Google Play (13%), then Screen (6%), then my email app (3%) and a small handful of other sub-3% services. That's about what I'd expect when the device isn't being used, as it's a percentages thing.

    What I can't fathom is why -- if it's doing "nothing" (i.e me barely interacting with it) -- it suddenly loses 10-20% of power in the blink of an eye when I do interact with it, or it can't last an hour or two when it reaches around 40% remaining juice. Is the lock screen showing the wrong value and after entering the PIN and tapping a few apps, it checks the battery status and goes "woah! that ain't right" and updates the value to show the real value? Even so, would that explain why cycling the power twice within a couple of minutes could drain 27% of the battery and then two more cycles a few minutes later made almost no difference?

    Any clues as to what might be causing random battery drainage or such battery life misrepresentations gratefully appreciated as I can't figure it out. Thanks in advance!
    07-23-2016 11:22 AM

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