How to fix Apple Watch battery drain after recent update?

So, you checked the Optimized Charging setting as I requested? Did you note that Updates automatically turn on Optimized Charging? If you haven’t checked it since the update, it’s likely on, unless you turned it off.

The Apple Watch has a tiny battery and that should come as no surprise. After a Watch OS update, the Watch and iPhone have a lot to do optimizing the new OS, syncing files and software, including third party software. These background processes consume a lot of processing power which subsequently consume a lot of daily battery capacity. Depending on the apps and data you have on the watches this can take a day or two to normalize and return to expected daily capacity.

Sometimes developers of third party apps haven’t optimized their apps yet for the new software or an app gets stuck in a loop trying to update. This is just something that happens and there is no way Apple can predict what third party apps will cause issues or have issues with an update.

To get your iPhone and Apple Watch back to normal once you’re experiencing longer than expected issues updating please do the following.

Unpair the devices

Force restart both devices

Re-pair the devices

Allow 48 to 72 hours for daily battery capacity to return to normal.

Unpair and erase your Apple Watch - Apple Support

Force restart iPhone - Apple Support

Force restart Apple Watch - Apple Support

In my experience and others the increased battery drain resolves itself after several days. After an update there is greatly increased power consumption caused by the system optimizing the update. See if this doesn’t resolve itself in a few days.

For some users, unpairing and pairing the Apple Watch again seems to help.

Unpair and erase your Apple Watch - Apple Support

Also have a look at the latest posts in this discussion:

Apple Watch battery draining fast - Apple Community

You’re experiencing multiple unrelated issues. Let’s tackle the slow charging issue first.

What model Apple Watch do you have and what iOS version are the watches on?

Are you using the Apple cable/puck and Apple Wall charger recommended for your Watch?

Is Optimized Charging enabled for your Watches? Here’s the path to check,

Apple Watch > Settings App > Battery > Battery Health > it’s enabled if the switch shows green. You can learn more about Optimized Charging at the link below.

About Optimized Battery Charging on your Apple Watch - Apple Support

After updates, Optimized charging is enabled by the update and you’ll need to turn it off following the path above.

Please confirm if your Apple Watches have Optimized Charging on or off.

My wife's watch, mine. It seems to be an issue for everybody. It is not only draining the battery but also taking forever to charge. I let it charge all night, and it is not even getting 100%. Yes, it is set up to charge in full, not only to 80%, which is BS.

Let's tackle the reality first. Before the last update, everything was working well, but now it is not. There is no other change but the last update.

But yes, Apple cable, Apple wall charger, and all setup as it is recommended. Also, I said that optimized charging is disabled. I'm using an Ultra 2 model (about eight months of use). The battery should not be an issue, but it was checked, too.

I unpaired and paired it again, at this time as a new watch, to ensure it was not a configuration or something related. But as I said, it all started with those creepy Apple updates again!