> I'm curious, does anyone with more knowledge know how Garmin are able to get so much more battery life out of their watches?

Yes, I can.

I have a Garmin 5 Plus and the reason it can get such great battery life is it's ####ing massive, with most of the volume devoted to battery. It also doesn't do a bunch of the stuff that the Apple Watch does, with all wireless connectivity requiring Bluetooth sync to your phone.

It's fairly rugged and a decent enough watch but, unless you're outdoors all the time, I wouldn't recommend it: it's bulky and somewhat ugly. I've stopped wearing it because I didn't find it that motivating in terms of keeping fit: ironically I did better before I got it, and am doing better again now I've stopped wearing it.

Also, that battery life tanks the moment you switch on GPS: then you'll be down to about 24 hours.

Overall I'd describe Garmin smartwatches as highly overrated.

I could also never get my Fenix 5 to give me acceptably accurate distances on twisty mountain trails. And, as you say, even as a big guy it’s just too bulky a watch to wear day to day. Maybe I’ll get another someday but my tracking needs are mostly just hiking distances and the Apple Watch eorks for that plus being nice as a day to day watch.

Feature set.

I have a Garmin FR645 "smart" watch. It lasts two weeks between charges if I don't use GPS a lot; if I run 5 times in the week (w/ GPS on) it'll go most of a week between charges.

But, it doesn't have much of an app ecosystem. Just a few widget-type things. Notifications are basic, and mostly unidirectional. The screen is nowhere near as nice as an Apple Watch. And no cellular.

But, for basic smart things - GPS, simple notifications, and telling time - it's excellent. And costs less than the Apple.

Until Apple can make their watch last most of a week, I'll stick with slightly dumber smart watches that I don't have to think about too much.

Another difference is the CPU, which is really bad on 645 (and all the others). If you play music from it it dries up the battery pretty fast. It goes nowhere near 2 weeks, as you say, for me at least. I’m keeping all the features active, though (bluetooth, gps, glonass, garmin pod, heart rate monitor).

Feature wise I honestly think that Garmin makes better sport watches, while Apple does better smart watches.

I only use HR and GPS when I'm exercising. Otherwise, they're off.

Probably at least part of it is that, at least the Garmin Fenix watches are pretty big. The newly-announced Fenix 6 apparently slims down a bit but they're still basically big hunks on your wrist. Personally I don't really mind but big difference from an Apple Watch.

Also, I haven't looked recently because I ultimately found my Fenix 5 wholly unsatisfactory for hiking distance tracking with GPS but the watch with GPS only lasted for about a day. (Which is what I basically care about for a smart watch.)

My Garmin Forerunner is about the size of the larger Apple Watch. While it only lasts 3-6 hours with GPS/HRM/Bluetooth on, it goes for at least 3 weeks on standby, which is what I want from my watch.

I have the Fenix 5x Plus. I effin love this watch. 100m water proof. Weeks without charging. Easy to read, always on display. Sapphire screen. Tons of fitness metrics (even more on the 6). And as far as size. I love the look. I bought a watch. Not a mini phone that is missing functionality. Garmin Pay. Wireless music. Takes calls. Up to 72 hours of GPS. 72 f-cking hours of gps. Not 18 hours of normal use. That is GPS.

I worked on a smart watch team. Turns out writing a simple while loop and a simple task model, cooperative scheduling, let us sleep our processor more often. It was also very light weight in terms of memory. Basically not having the burden of traditional heavy weight OSes really helped get good battery life.

It is the screen, and the discipline. I read a review that said they don't allow 3rd party watch faces that update every second, for example.

Garmin just introduced a watch with an AMOLED touchscreen, the Venu. According to the reviews I've read, it is basically the same watch as the Vivoctive 4. The Venu gets 2 days of battery life, the Vivoactive 4 gets 7.

I'm guessing it's because Garmin has a lot of excellent embedded hardware folks.

I think it’s more that Apple prefers a powerful OS on a slim devices over long battery life.

Even if they don’t already have a lot of excellent embedded hardware folks, which I doubt, I don’t think they would have trouble hiring them, if they wanted to.