Having been a very happy Galaxy Fit 2 user, I bought the Galaxy Fit 3 the first moment it was available.

The device is advertised as getting 13 days of use on a single charge, but I have not found this to be the case AT ALL.

At most I get about 6 days charge, when with the Galaxy Fit 2 I often would get more than 2 weeks before I needed to recharge it.

Not being anxious about battery level is the main reason I picked these devices.

• I do not use Always on display.
• I have screen timeout set to 4 seconds (lowest level).
• I do use raise wrist to wake. 
• I do not use stress measurement.
• I've turned off a lot of notifications so I'm only getting the essentials like IM, calls, SMS, etc - so it's not vibrating a crazy amount.
• I also have been on an exercise break, so I haven't even been tracking workouts.
• Send diagnostic data to Samsung is on (perhaps I should turn this off?)

But the interesting thing is that I've been watching it closely and it seems that during the day it generally performs very well with minimal battery usage. However at night, I put it into sleep mode and it often drops 10% or more overnight - despite the fact that the screen is off the entire time.

I immediately assumed this was due to the sleep tracking features (blood oxygen, snore detection), but I turned all of them off. I then thought perhaps it's the heart rate every 10 minutes, so I switched that to manual only yesterday morning and fully charged the device. By yesterday evening when I went to put it into sleep mode it was still at 100%. I woke up a few times during the night, and as is often the case I noticed that the green light at the back of the watch was flashing a lot and for what seemed like a very long time. Considering I had disabled regular heart rate monitoring I don't even know why this was coming on at all. Some points I would read for a few minutes and see the green light emanating from my wrist continuously.

Anyway - I woke up in the morning after about 8 hours sleep and turned off sleep mode. The watch was at 87% - a drop of 13% overnight. That is basically the opposite of what I used to see with my Galaxy Fit 2, which usually, with the screen off overnight, would rarely drop anything overnight.

Anyway, I'll continue to see what happens with it now that I've disabled heart rate checks every 10 minutes - but I must feel like something is wrong and either the hardware or software has a bug that needs to be fixed.

Software Version: R390XXU0AWLL - I've checked for update and found none.

I'm almost tempted to go back to my Galaxy Fit 2 which even after multiple years is still regularly lasting for two weeks without charging.