Venu 2 losing ~50% battery over night?

So far for me no significant loss overnight with PulseOX on for sleep. If it keeps happening that would sound like an issue with your specific watch to me. 

I've seen inconsistent battery performance with overnight sleep and Pulse Ox tracking. Some nights the watch uses as much as 17% battery and some nights as little as 4% battery.

Regarding Pulse Ox, check the settings occasionally. I found mine set to measure all the time, after I set it to measure only during sleep. There's another thread where someone else experienced the same thing -- the watch appears to change the setting on its own.

Did you read the rest of the sentence? Between 4% and 17%. My original Venu uses about 6%. Lately, the Venu 2 has been more stable -- I haven't seen the ridiculous drains I saw the first few days. That's a good sign. 

Hey there! With the pulse OX on it will drain the battery, however, can we give it a few days to see if this is consistent? Then you can keep me updated.

I've had similar issues.  I think i have narrowed it down to GPS activities during the day.  It has happened twice to me after turning on the golf activity while at home to mess with the settings.  I noticed that my battery life that night would go from 60% to 10%.  

FYI: I just chatted with Garmin support about this issue and they told me it was addressed in 3.40. I noted in the 3.40 notification thread that it did not mention this as a corrected issue but the support person stated specifically that it was. 

I'd love it if someone from Garmin could address this, since I've been having the same problem, and phone support just yesterday had no evidence it was fixed in 3.40.

I've done a factory reset, turned pulse ox completely off, uninstalled everything from ConnectIQ (including Spotify), and I still have sporadic battery loss overnight. Once or twice a week, it'll drop from 50-75% to 0-15% overnight, while the face is off. The morning after, I've watched the % remaining go from 10-15% to 0-5% in less than a minute. I haven't noticed any particular causal pattern that triggers it (it definitely wasn't GPS activities for me), but it'll be interesting to see if the update makes any empirical difference...

My Akku on the Garmin Venu 2 is empty after 21 hours, without always-on-display, deactivated pulsoximeter and not much acitivity. Very bad battery life on the Venu 2! 

@8234028 This is not normal. With the setup you describe you should get several days on each charge. I suggest you call Garmin support.