Why my battery on Samsung Galaxy A8 2018 is draining fast?

[Android Central Question]

I bought my Galaxy A8 about a month ago. First, everything was perfect, the battery life was great. But, after I update the new software (two weeks ago) my battery started to drain very fast! Most of my battery usage is Screen, Android OS, Device idle, Android system. I have everything turned off (Location, Wi-fi, auto brightness etc)
I think that the update is the problem.

Example, my battery for 8h at night drain 17%.

Any solutions?

 

[Rukbat]

Try going into recovery (Volume +/Home/Power) and do a cache clear. (Do not clear storage or do a factory reset, just clear the cache.) See if that helps.

 

[Fernandoagstn]

Is that working, many battery life problems on A8 2018

 

[B. Diddy]

Is that working, many battery life problems on A8 2018

Are you the OP? Did you try the cache partition wipe, as suggested by Rukbat? https://www.hardreset.info/devices/samsung/samsung-galaxy-a8/recovery-mode/

 

[Alex B6]

I bought my Galaxy A8 about a month ago. First, everything was perfect, the battery life was great. But, after I update the new software (two weeks ago) my battery started to drain very fast! Most of my battery usage is Screen, Android OS, Device idle, Android system. I have everything turned off (Location, Wi-fi, auto brightness etc)
I think that the update is the problem.

Example, my battery for 8h at night drain 17%.

Any solutions?

Roll back to Android 8, I had the same issue updating to 9, my a8 is 8 months old. When surfing the net or playing games, it gets very hot and battery life is like 6 hrs.
Rolled back to 8 and it's a new phone.
The trouble with new ui updates is that it gets written on top of the previous ui. This is what causes the bugs. If you bought a brand new a8 with Android 9 installed from factory, it will be bug free. If you can completely wipe the Android 8 from the phone and then install 9, it should in theory be bug free. I have discussed this with Samsung support and they said this is not possible as you still need files from 8 to make 9 work when updating.