FENIX 8 Solar Battery Life: A Closer Look at Real-World Usage vs. Advertised Expectations

It sounds like you are doing all the right things (I don't have auto connect to sensors off and while I don't have wifi connected, I don't have it off either). If after you turn off PulseOx, you don't see significant battery improvement, there is clearly something wrong and a factory reset and/or troubleshooting with Garmin Support are the next steps. I'd suggest after the factory reset, that you let the watch charge for couple of hours making sure it is turned off and then setting up the watch using Garmin Express before you pair the watch to your phone.

You could have a hardware problem.

I'm sure you already know this but, the 30 day advertised battery life is in Smart Watch only mode. Since my latest charge, I lose 3 to 4 percent a day in Smart Watch mode (non GPS activities don't seem to have much affect on battery life). While using the watch with GPS activities, I lose a little over 1% per hour (that is with GPS only turned on). I also have an external Heart Rate Strap connect Ant+.

I've had a 51mm Fenix 8 Amoled since release. I run all background body monitoring so I expect battery life to be more limited. However since the last update my battery percentage drops like a rock. I record about 2 activities a day as well. Has anyone else noticed a recent speed up in battery drop?

This is my experience:

• PulseOx disabled
• Wifi disabled
• Notifications disabled
• I do not wear it at night
• Used default face with just steps plugin and battery
• At most 1h of activity (running or fitness indoor, ie not using GPS)
• Night mode between 22 and 7
• Brightness 20%
• Touch off
• No music

In these conditions battery lasts at best 12 days. I bought 1,000+ euro watch (Sapphire Solar DLC 47mm) to find out that the claim of 21 days and 28 days with solar it's just a lie.

I understand watch was tested in laboratory but if Garmin claims that the battery should lasts 21 days in smartwatch mode with normal user activity and 28 days with solar and I buy a new watch used in the conditions above, with not even notifications enabled, and the battery lasts well below 50% of 28 days I call it with its name: a scam.

The battery of Fenix 8 51 amoled is declared to last 29 days and 13 with screen always on.

https://www.garmin.com/es-ES/p/1228171/pn/010-02905-40/#specs

I get more than this numbers.

'According to the official calculation for smart mode with a 30-day battery life' - which it is doing. Smartwatch mode doesn't include activities, music, and syncing/notifications, surely? It's in it's most power-saving mode acting just as a watch, not tracking 60 min activities 18 times. My 965 is rated at 23 days for smartwatch mode, but mine says 54 days when I put it in battery saving mode which is essentially just acting as a watch. I'm looking at the F8 and tbh this seems...fine?

I am not sure I understand what you mean fully, however Fenix 8 51 is given for 30 day as smartwatch in "typical use" with no solar

https://www8.garmin.com/manuals/webhelp/GUID-EECCAC99-90D6-4AB1-9A3A-EC433D3365E2/EN-US/GUID-40B16F18-75A1-4B3E-8F1A-AB4919BC9E51.html

I am not sure what "typical use" means but to me it means that you at least use the watch as smartwatch. I do not even do that, I have all notifications blocked, touch disabled and use the default face. If what Garmin meant is that battery can last up to 30 days with NO use at all it should be written as such, the way it's advertised is deceptive at best

For my F8 51 Amoled is 14 a 15 days  with Screen AWO and 28 a 29days with just wrist mode. The saving power is always off.  Oxigen  pulse only sleeping mode. The battery is amazing 

With AMOLED we agree, battery is fine, but many people reporting here issues with Solar MIP, which should be better than AMOLED and it's not. I'm not surprised they are frustrated, however Smartwatch use, should exclude any sports activities..