iPhone 12 with iOS 15.2 - battery life dropped 85% in 5 hours?!?!?

[K9rescue]

Wow, my iPhone usually lasts all day. I upgraded to ios 15.2 yesterday. After light use today, my phone is almost out of power after 5 hours. That's less than half the capacity it was.

What's the deal?

 

[now i see it]

Battery SOC (state of charge) calculator lost calibration.

Discharge the phone until it shuts off (this will tell the SOC calculator where the bottom is) then charge it all the way back up to 100% and let it sit plugged in at 100% for 15 minutes. (This will tell the SOC calculator where the top is)

 

[papbot]

Battery usage right after a major update will be at its highest. Let it go for another day. Then just in case there is something significant stuck running you could do a forced restart to completely shut everything down. Running the battery down before re-charging is a good suggestion. I haven’t run it down till it shuts off for many years but I will occasionally run it very low - 5 to 10 percent - and then charging again. That does help set things right.

 

[Samdh90]

I second what @papbot stated. It might be nothing more than the usual maintenance tasks that run when you install the updated iOS. Also though, just because it is not widely reported, you still installed a beta pre-release build. There could be bugs that are negatively affecting battery life.

What the phone quite warm to the touch, one thing to note, at least this site(I am sure there are others as well) will run the battery more than normal. It has something to do with the ads on the site. This will also cause heat buildup right around the camera. Try using an adblocker and see if that helps.

If all else fails, you can always roll back to 15.1 but if you backed up at 15.2, that can be a pain in itself.

 

[K9rescue]

Thanks for the replies - I'll give it a shot.