My S3 Mini is exhibiting weird behaviour: sudden the battery drops, goes back up after rebooting/plugging in, what is going on?

[AC Question]

S3 Mini - weird behaviour: sudden battery drops, goes back up after rebooting/plugging in

Recently, I've noticed that the battery on my Galaxy s3 mini is dropping like a stone throughout the day, with only limited use.

For instance, it'd be at 100% when I take if off charge at around 8 in the morning. With browsing a couple of pages infrequently throughout the day (say 2-3 times, no more than 5mins at a time), it would have discharged entirely by around 5:30PM. This is with wireless, location services, syncing, etc all disabled. The biggest battery usage is Android O/S at 30-50%, with other Apps at up to 10%, then screen at around 40%. According to wakelock detector I'm only experiencing around 4% wake time. Screen brightness is set to 25%. Temperature peaks at ~33 when in use and ~25 all other times.

What I noticed was that once the battery reached around 50-40%, it would plummet by around 20%, then gradually decrease until it switched off. To make things even stranger, I noticed that if I restarted the device after this it could report a lower batter usage, but as soon as I plugged it into the charger it would jump back up again.

Yesterday, I managed to get a bit more life out of it by clearing the cache, reaching 70% by the end of the day. As a test, I left it on overnight without charging and it had gone down to 50% by this morning. By midday, it reached that magical spot between 40-50% where it plummets - down to 25% this time. I restarted the device and it reported 15% battery. I restarted device and plugged it into the charger, and it was back up to 40% again.

Has anybody seen this sort of behaviour before? The phone itself is getting on 18months old so I suspect what I'm seeing is the gradual death of the battery?

 

[belodion]

Re: S3 Mini - weird behaviour: sudden battery drops, goes back up after rebooting/plugging in

I think it could indeed be battery failure, although I don't see why Android OS usage should be at 30-50%. Take a look at the battery itself, and see whether it is distorted or bulging in shape, a sure sign of failure.

Posted via Android Central App

 

[Clockwork52]

Re: S3 Mini - weird behaviour: sudden battery drops, goes back up after rebooting/plugging in

Thanks. I took a look at the battery and there was a very very slight bulge at the bottom right. I'm talking so minimal I wouldn't have noticed without specifically looking to find one.

 

[Rukbat]

Re: S3 Mini - weird behaviour: sudden battery drops, goes back up after rebooting/plugging in

Sounds like a dendritic short at about 50-40%. This is a "feature" of lithium technology. (The industry is working on a way to prevent dendrites, but they don't have any batteries under test yet - they're still thinking out ideas.) There's no fix - you have to replace the battery. The good news is that a good new battery (check at Amazon) is about $8.

What happens is that a crystal grows across the battery, shorting it out, using up a little bit of charge, then shattering due to the current surge through it. It's usually enough of a short to turn the phone off, but when you turn the phone back on you've lost about 2% charge, and everything works. And the same battery won't always grow a dendrite at the same point every time (or even through every charge cycle.)

(BTW, it's technically covered under the warranty, since it's a design defect, but try convincing the store, the distributor or even the manufacturer of that. I know - I owned cellphone stores and tried. They consider batteries to be "consumables" - when it goes - for whatever reason - you buy another one.)