Fenix 8 Solar 51mm - My Battery Test Results

Very similar to my experience. Now I am testing F8 solar 51mm with 7X Pro. Both watches are disconnected from phone and WiFi and Bluetooth are turned off. I am getting double discharge rates on F8. 7X Pro discharges at around 1.7% per 24 hours and F8 solar 51mm discharges at around 3% per day. Both watches are sitting on my desk for many days doing nothing. This doesn’t make any sense. F8 should have same battery life if not little bit better. 

What is the advertised battery life for the watch with Garmins standard settings?  Also your pulse ox is on at night, which will cause more drain than what Garmin calculates for advertising purposes.

They advertise 30 days. My pulse ox is not on. 

This is what Garmin says;

BATTERY LIFE (SMARTWATCH MODE): Up to 30 days (48 days with solar)

Yes, my pulse ox was on at night that's why I added a field called "Daytime Discharge %" to "Data & Charts > Data" section which doesn't take the pulse ox discharge % at night into account. It does reflect the activity and GPS drains though.

Daytime discharge percentages add up to -65% (including activities) which roughly means pulse ox drained the remaining 35% in the past 19 days.

On your testing notes link, it shows this.  So not sure which is which.  For sure contact garmin support on the phone.  They could walk you through other things to improve battery life.

I think you're mistaking akiakic for me. I did the testing and my pulse ox was on during sleep. akiakic on the other hand is another Fenix owner and he says that his experience is just like mine but he has his pulse ox off.

Yes, exactly. I also have F8 AMOLED 51mm that I wear daily while testing the other two solar ones. So they are doing absolutely nothing. The only sensor it is on is heart rate. BTW F8 AMOLED 51mm has more battery life than what Garmin specs say. Specs say 13 days with AOD and I am getting 16+ with light GPS usage. Crazy. 

I had similar results with pulse ox in at night during to tests.  Drain was hight night and day with a drain rate of about 0.25/hr.  During a third test, I turned pulseox off entirely midway through the test and it seemed to drop drain rate both at night and during the day (to about 0.17/hr).  But, still ended up way short of estimated battery life. Doing a fourth test now to confirm.  Might be a problem with pulseox, but seems like battery estimation is way high.

Thank you for the test. My battery is also very bad. Garmin says 30 days and I have 16 days without GPS. Garmins software department is full of interns and they charge you 1000$ 

got my 51mm solar since 26.11.2024

first charge got me 19 days with 8% left. i did 10hrs gps and 1hr nongps activitys. one day with 88k lux (not much more days with sun)

during this cycle i also did 3 updates.

some observations: the first 5% (from 100 to 95) drains quickly.

after that it drains 3-4% without activitys and 5-7% with gps activitys.

~2% each 60min gps

if i would not do any activitys at all (that is what garmin means with smartwatch mode (or what ever its called)) this would lead to ~30days without sun. 

best regards

edit: no pulsox, portal watchface, 4sec backlight, no batterysaver during night, sleepmode: 22:00-06:00, no notifications. rest of the settings are the same i think.

edit2: dont got any restarts or other problems so far. fingers crossed

edit3: currently on 12.35 - 2 days, 2hrs gps, 40k lux yesterday - 88% left