After update to watch os 3.1.3 the battery died within 12 hours

I'm having the same issues as you and everyone else after the iOS 3.1.3 update. During work my phone is turned off, the only usage my watch gets is from tracking my steps and etc. Before the update I would go the entire day at 70% before a recharge, now with the new update, the battery lasts for less than half the day. I'm sure Apple is aware this, lets see if they fix this issue.

I updated my Series 1 on Friday I believe and I noticed the problems with battery life beginning Saturday. Sunday and Monday were both easily less than 10 hours which is insanely bad since with 3.1.1 I was getting me well into a second day's use between charges. Amazingly, after restarting both my phone and my watch last night, and taking my watch off the charger this morning at 8:30am - it's now 2:30pm and the watch shows 93% available battery!!! This is markedly "Better" than even 3.1.1 was able to produce. I'm not sure what to think just yet...

Spoke with Tech Support, they ran diagnostics and my watch battery is healthy. After that was done, the troubleshoot was to unpair and re-pair my iPhone and watch, turn off notifications that aren't needed, wait a full day and go from there. It's pretty hilarious in a sad way that those who updated to iOS 3.1.3 last week are having this issue. Try what the Tech told me and go from there. Good luck.

I hate to admit it, but closing all iPhone apps and restarting both my iPhone and Watch solved my issue. Started at 6:30am today and it's 12 noon now and my Watch is on 86% now.

Sheesh, I feel like a typical IT guy who didn't even try a reboot. Sorry Jonno for all the crap.

I'll give Johnathans advise a whirl too... I had the battery death issue too... & now my month long activity rings went kaput on me... I think that bugs me more than the watch not lasting the whole day - End rant

I hate to do "me too" post but I've had this exact issue.. I could go the entire day without a problem with the previous WatchOS 3.1 release. This one I looked at my watch one moment and it said I had 60% power.. an hour later it said 10% and wanted to go into power saver mode. The only difference was the upgrade on WatchOS. No new apps were installed (other than what was there previously.

Apple Watch 1, OS 3.1.1 Aluminum Case 42mm

Resolved!

11pm and I'm putting my Watch on charge with 53% remaining after 17 hours use.

I can confirm that rebooting my iPhone resolved the poor battery performance on my Apple Watch following the 3.1.3 update. It must have been the iPhone draining the Watch or something.

Spread the word to restart your iPhone and Apple Watch together.

I have tried these suggestions. Even restored completely from backup and eventually as completely new. The battery drain continues even with no 3rd party apps on the watch. The only exception is setting up the exchange calendar invites to an un-synced folder. I have routed mine to trash after they've been added to the calendar. This was not an issue prior to the update and I don't think and it would magically become a problem after the update just by coincidence. It would be a bit ridiculous to expect a change in workflow on my phone simply because of an iwatch update.

I have not gone through all the complications one at the time but I use weather, calendar, date, world time, alarm and timers with a couple of watch faces. All the stock ones. If these are causing the drain, then there is definitely a big problem, since, without them, there is no much purpose for the watch. For my part, I do not know how to remove a default app from my watch.

Yes, it wasn't making much of a difference. About10-12%/hour with only the default apps. I reset it again and that seemed to sort it. The update did messed it up. Would have been easier to have the watch do a full reset when the update was applied. It's been pretty good all afternoon after the full reset. I did not even tried to restore a backup so it was pain to setup again but got it working.

I went through all of the sock suggestions provided by support: none worked, and it was only a complete and utter reinstall that brought my original version (One) watch back to health.

[ That's the bit when you point your phone at the swirling watch screen. ]

... And immediately I saw a difference in the original stock watch faces.

Which means that the update was running the old faces. Don't know if this could have been causing my problems, but after an absolute clean reboot, and re-install: I have finally sorted out my own battery issues.

Really not impressed with the apple programmers here.

Hope this helps buenor.

I agree, it is exactly what I had to do to get it back to normal. The generic suggestions were a real waste of time. The first time I reset it, I let it restored the settings and that didn't work. It was after a full reset - again- and setup as new, that things got back to what seems normal behavior.

I'm doing a "me too" post as well. My phone has been rebooted. My watched died on the road, so it has also been rebooted. I'm on the latest update. My watch was at 100% when I took it off the charger at 6AM. At 2PM it was down to 12%. Before the update I would've left work with better than 50% and enough to make it through a 45 minute dance class after work and then some. Right now, I have to charge it half way through the day because it'll die on my before I get to the Gym. I gave up Fitbit because it was randomly dying on me. Please don't make me give up my Apple Watch too. I <3'ed Apple before this update.

I have the Series 2 Sport Edition and I had the same problem... the way I solved it was restarting my phone and watch... now I am having great battery life... almost 2 days... and that's with an average of 4-5 hours of workout tracking through Under Armour App... I also had to reinstall Under Armour App after the update because for some reason it kept starting by itself mysteriously around 2-3am and running til I woke up at 7... Anyhow, if any of you still have this problem, my recommendation is restart all devices, if that doesn't work, unpair and re-pair the watch...