Battery problem watchOS 8.5.1

If the battery drains too fast after an update, see all the replies to:

Battery Drain since watchos 7.4 - Apple Community

WatchOS 7.5 battery drain - Apple Community

FWIW, in some cases, unpairing the watch, completely erasing it, then pairing and restoring the backup will resolve the battery draining issue after an update. (Simply unpairing and pairing again may not work.)

Unpair and erase your Apple Watch - Apple Support

Also, some people have found that simply waiting a few days after an update resolves the battery draining problem.

Yet another "same here".

On my apple ID I have 2 x iPhones Pro's, 2 x iPad Pro's & Watch S6 - and lots of AirTags. (plus an iMac)

All worked fine on OS's 15.4/8.5 until 3 weeks ago when I updated them all to the 15.4.1/8.5.1 not because I had any battery drain issues but my wife was having issues with her MFA Hearing Aids intermittently losing Bluetooth connectivity. So after seeing that a key fix in 15.4.1 was a BT fix for MFA Hearing Aids I upgraded ........and what a disaster it has been ever since.!!!

The No 1 issue was and still is a massive battery drain nearly all -but not always every day - with a classic example just like ChrStormer in that last night as part of data gathering exercise for Apple Support I charged my iPhone 13 Pro up to 100% then took it off charge and just left it. This morning it was done to less than 40% after just 8 hrs and with zero screen time found Siri had consumed c70% and Find My the other c30% of my battery usage. Even stranger is that Siri is turned off as well.......

Apple Support appear to be lost on this issue and are not even accepting that there was a problem with the latest 15.4.1/8.5.1 updates despite having had access to my iPhone's diagnostic files.

I now have to take a Power bank when I am out for the day especially for my Watch that now lasts 4 hrs v a good 1½ days on 15.4.

I have tried any matter of restores/resets/setting up a new on the iPhones & Watch but it keeps on draining - the key factor was last night's issue - just what does Siri access on my iPhone the whole night that drains my battery- the last 3 hrs its happening again with Siri on c85% of battery usage with zero Screen On time showing.

I am a long time served IT professional and have used Apple products since the very 1st iPod days in a personal & a business environment - but this problem has even me stumped and losing patience as fast as my the battery's are draining on all my devices running the 15.4.1/8.5.1 updates.

Does anyone have any ideas that can help Apple support identify & fix this problem.🙏

Same. Series 4 44mm was working like a champ till I updated today. Now the battery is draining rapidly. Went from 100% to 5 in less than 6 hrs of just watching movies. Kind of a disappointment.

Did you found any solution? i got the same issue, the problem persists 2 months ago when i uptdated to watchOS 8.5.1