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

I’ve got  a 51mm solar and I’m smart watch mode and my average drop per day is between 3 and 4 percent.

PulseOx - off

Gestures - off

Backlight - 20%

Sleep Mode - Power Saving watch face with HRM active

I would guess that updating maps at the beginning which can take hours via Garmin Connect consumed some battery life.

Music consume 5-6% per hour. The flashlight will consume a lot of battery.

if you get a lot of texts and notifications from your phone that can affect battery life because the backlight comes on with each notification.

Each users actual battery life is different but, by taking some time to configure your watch for optimal, I’m sure you can get more days from your watch.

Thank you for your advice. I was replying to this message. I fully charged it 1 hour ago and now it has consumed 1%. I used a laptop to charge it for 2 hours and 40 minutes this morning. It consumed 1% in 1 hour. This is incredible. In fact, when I updated the map after I first got the watch, I updated it on Garmin Express. It updated very quickly. I turned on the phone, text messages and WeChat for daily notifications. I only used the flashlight for about 5 minutes during the whole period.

The 30 days were guaranteed to have been achieved/simulated by Garmin under the best laboratory conditions, which a normal user can hardly achieve. This is more of a theoretically possible value under the best conditions (always optimal GPS reception/always optimal temperatures etc.). You would also have to know exactly which settings Garmin used here...

Sure, I also understand that Garmin likely maximized the battery life of the FENIX 8 Solar Mip 51mm version by setting extremely strict testing conditions in the lab, which are hard for regular users to replicate. For example, even though it’s called “Smart Mode,” during testing, the watch probably doesn’t receive any notifications, the backlight never turns on, and no one interacts with the watch—it’s just sitting there displaying a static watch face. Well, under those conditions, maybe it really could reach 30 days. Another reason is that the FENIX 8 Solar Mip is the flagship model of the FENIX series, so it’s expected to have the longest battery life in the lineup, showcasing advancements in technology.

Mine lost 2% in the first couple hours after full change and the settled in to 3% - 4% per day after that.

I found that after full charge, all the 6 heart rate lights turned on, but I did not exercise, I don't know why they all turned on, is this a software bug? I took off the watch and restarted it again, and it seemed normal, can Garmin team pay attention to this problem and correct it?

Update to firmware 12.35.  Then restart the watch and do a hard reset/factory reset.  If still no improvement, call garmin support.  You might just have a defective watch.

My 47mm is draining 11% per day, getting about 10 days out if it. This is with no notifications, no activities, gesture on with 20% backlight,  and pulse ox during sleep. I think almost half the battery life as advertised with settings like this is pretty terrible. I don't think i’ve read or seen anyone with a Fenix 8 MIP getting close to the advertised battery life. And I can be wrong but for previous models this wasn’t the case. 

If you look at all of the posts in this thread, you will see that I posted I’m getting close to advertized battery life. 51mm Solar

There are plenty of people getting great battery life.

PulseOx on is going to drain your battery very quickly and is not considered Typical Use.

With touch screen, there is no need to have gesture on which will help.

Using sleep focus with a power saving watch face can also help.

Unless you have defective hardware, IMO, you can achieve much better battery life if you effectively manage your watch configuration.

I see that. Thanks for the reply/advice. It seems the majority of posts I see are folks like myself who have turned off many of the bells and whistles so to speak to reduce power consumption and are still getting serious drain. I would also consider typical use case to be what the watch default settings are + some average daily use. I left everything stock except having pulse ox during sleep on, then turned so many things off or to some diminished state. 11% drain a day with: Stock face, sleep face, WiFi off, auto connect to sensors off, gesture with 20% backlight, notifications off, no activities. I’m barely using the watch as of now, when I get back to training what sort of battery life will I get? I can be wrong but is pulse ox really accounting for 5.5% of that? I’m not necessarily worried about the 10 days of usage I’m getting, I’m more concerned about the activity usage. I bought this bc Apple Watches couldn’t keep up with the duration of my events. If there are issues with daily use what will activities be like?

I’ll try turning the pulse ox off. If that doesn't fix the issue then a factory reset. Otherwise might have to call support.