The more expensive watches (Fenix) also have long battery lives: lasting up to a month on a battery that can fit in a watch. The processors still have to sip power.
The funniest thing is that earlier versions of the Coros even used the Garmin map format (though as many small files and not a single/small number of .img). Though they have switched to the open PMTiles format in later versions.
BTW, I had a Fenix 7x solar (before a Fenix 8 AMOLED) and it would usually 'only' last about two weeks. I think you can only reach Garmin's stated time if you disable a lot of functionality.
Garmin gets almost 30% more battery life in exchange of not being as fast (30 days)
> I think you can only reach Garmin's stated time if you disable a lot of functionality.
Turning off always-on Pulse ox gets you there. Turning everything off except telling time gets you 2.5x the battery life (69-71 days)
That's with running activity tracking including GPS for about an hour a day, and continuous heart rate monitoring.
At least on my device (and my body) the spo2 sensor is very finicky, requiring absolution stillness, and even at that I don't think it's accurate. So I don't use that.
I also discovered recently that simply using a custom watchface - even one built with an eye toward efficiency - lowers my battery life to about 2 weeks. The native faces enjoy privileged operations and are thus highly efficient. But custom-coded stuff apparently runs in a sandbox that has the effect of costing much more power. That's unfortunate, because my custom face used custom high-legibility fonts (derived from what's on interstate signage), making it noticeably easier on my aging eyes. The built-in fonts aren't great for this.
It's brilliant coros sticks to MIP though - the moment I cant buy MIP Garmin when I update the watch next time, I don't buy Garmin.
Good watches, Coros, though, I wish them success.