After my old battery puffed up, it was time to buy a new one for my Galaxy S3 (GT-I9300) on stock ROM. After I got my new battery, I put it in and turned on the phone as I had some urgent messages to check. I was supposed to charge it to the max but I skipped that part because of urgency.
Well, I noticed that the screen flickered when the battery was 23% and the phone switched off. I decided to charge it to 100%. After I got the green light I turned on the phone and I noticed that the battery jumped down to 88%; indicating that I needed calibration.
I tried the good ol' discharge-recharge to 100% method, but the battery wouldn't go below 23%. I decided to use some app, like Advanced Battery Calibrator. After following the on-screen instructions, it asks to switch off the phone and let it charge to 100%.
The bizarre part is that as soon as the battery reaches 90% (in switched-off mode). it jumps back down to 20%.
I do not know what is causing this. Any leads would be appreciated.