Battery performance

[davehorne]

I normally will see 23 to 25 hours remaining displayed in Settings / Device care / Battery.

For the last week, quite unexpectedly, it was 17 or 18 hours (according to Device care / Battery).

I could have posted here and complained, but I didnt. 

Today I looked at Device care / Battery and it's back 1 Day or so. 

These issues seem to correct themselves. 

[Tourbillon De La Vie]

And also make it difficult to troubleshoot reliably 

[Glenntech]

If you recently have done a software update. Especially if it's a large update.
Can go through a learning usage process for a day or two.
Like you say it usually sorts itself out

[Joeeye]

It's a prediction based on your current usage pattern since the last charge. If any deviation occurs from your typical routine (assuming it's fixed in the first place) that prediction can vary.