Wi-Fi - The Phone Battery killer?
 

Yesterday I came back from a trip (Boise). When exiting the plane, I switched off Wi-Fi on my phone because the plane's Wi-Fi system interferes with the phone's data when on the ground.

I forgot to switch the Wi-Fi back on. I did put the phone on my wireless charger at work, but neglected to plug it in when I came home (5PM).

This morning, about 14 hours later, I checked my battery after seeing I forgot to charge it overnight. To my surprise I found it to be 84% full! That is amazing. Usually I lose more than 1/2 my charge in a workday. It has to be the Wi-Fi doing this, since it was the only thing different.

How old is the battery? They get flaky with age.

Yep, it can suck down a battery pretty quick if it is in some sort of "smart switching mode" or always scanning to connect to the strongest network.
Also, if you have a bunch of "Wi-Fi only" stuff enabled (more frequent email checks, data syncs, app updates, etc.), that will obviously drain it down faster too.

Not sure how old your phone is but most of them now have a sleep/hibernate option, which disables Wi-Fi and cell standby (typically the biggest battery hog) for specified periods.

It obviously went into hibernate mode last night. Going to see if I can get it to do the same on Wi-Fi.

Phone is a 2 year old Samsung S8. It will be replaced as soon as Samsung ships my S10...

Tonight, with Wi-Fi on, the phone has lost 7% in 3.5 hours.

I always disable my wifi when I leave the house. If you look at it, when wifi is enabled it's constantly searching for available wifi networks.

I wish there was a way for this to be automatic, maybe based on GPS. If you are outside a certain location, Wi-Fi is turned off, unless specifically turned on.

You can do this with Tasker

Wow! That looks like the ticket.

I need to install it on my wife's phone to kill the sound when she is in church and then switch it back on!

OTOH, my Galaxy S10 shipped today, to be delivered tomorrow!