I found a guide somewhere on the internet on the best way to calibrate battery stats on a rooted device (to fix incorrect battery reporting after flashing) when I had my old hero and I use it a lot to this day when flashing new roms/kernels so I decided to share the best way to do it here.
First and foremost charge the phone to 100%(Even if it says 100% wait about 5 minutes or so just be sure.)
Once it is at 100% go into data/system using your preferred explorer and delete the batterystats.bin file there.
Unplug the charger and reboot to recovery, wipe cache and dalvik cache and wipe battery stats once more while you're there just to make sure they're gone.
Power the phone down and plug it back in. Charge it to 100% while it's off (the battery bar can be deceiving so even once it shows it's full give it five more minutes or so to be sure) and then power up.
Once it is booted to the OS you should now see that the battery bar is at 100%. If not start back at step 1.
It had come to my attention that this phone does not have a smart battery so fully discharging it is not a good idea. However I would recommend discharging it to below 20% before recharging. Thanks to hechoen for the info straight from Samsung.
After that you should have a fully calibrated battery and see correct battery stats.
Everybody enjoy! If this helped you please hit thanks!
*Thanks to whoever it was that wrote this up in the first place. If I knew who it was I would give proper thanks.
Sent from my SGH-T959V using xda premium