Samsung Galaxy S3 Battery issue
I have had my phone for just about 14 months now, I did a firmware upgrade in December last year at a Samsung Service Centre and since then have noticed that the battery doesn't last as long as it used to. Now the last couple of weeks the phone would switch off and will not switch on again, the battery percentage shows 35% and then it freezes and after a minute it switches off, when I put it on charge then I'm able to switch it on again and while charging it, the battery percentage will then show 33%.
Other times it will give a low battery warning on 15% then suddenly switch off. When I put it on charge and switch it back on again it shows 0%. Some times the battery will last a day other times I have to charge it 3 times a day.
My Wi-Fi is switched on during the day and at night I use my mobile data when needed and then the Wi-Fi is disabled. When I go to bed then I make sure that both Mobile Data and Wi-Fi is disabled. Some nights my phone battery percentage is 53% and in the mornings it shows 3%.
The phone usage is the same every day.
Is it the battery or could it be the phone or some other app draining the battery?
Any info will help as I don't want to buy a new battery unless I need to.