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Battery life - unrealistic expectations?

So I went for a 3 hour bike ride on Sunday with a fully charged 935. At the end of the ride the battery was 80%. So that's a 20% drop in 3 hours. At that rate, the battery would only last 15 hours in GPS mode. I thought it could last 24 hours?

To note, I had it paired with a HRM-Run strap, had GPS + GLONASS enabled, with 1 sec. recording, and 100% backlight brightness. Even so, it still falls significantly short of the expected battery life. Not that I ever do any activities lasting anywhere near 15 hours, but still.

0 rtperna over 8 years ago

So I went for a 3 hour bike ride on Sunday with a fully charged 935. At the end of the ride the battery was 80%. So that's a 20% drop in 3 hours. At that rate, the battery would only last 15 hours in GPS mode. I thought it could last 24 hours?

To note, I had it paired with a HRM-Run strap, had GPS + GLONASS enabled, with 1 sec. recording, and 100% backlight brightness. Even so, it still falls significantly short of the expected battery life. Not that I ever do any activities lasting anywhere near 15 hours, but still.

As others have stated, your 100% backlight brightness is nuts. I've never had mine past 20 or 30% (whatever the default is). 100% would sear my retinas out of my eyes.

I use GLONASS as well, and my watch burns 3% per hour while the GPS is on. FAR less burn than what you're seeing. It's your backlight brightness that's killing your battery, dial that way down and you should see a huge improvement.

0 Lemos_pt over 8 years ago

at what percentage do you guys recharge it?

0 ekutter-dnu over 8 years ago

The only way you will know how long it lasts is to let it go to 0%. You are asking too much to expect 20% battery drain to be accurate to a point where you can multiply the activity time by 5 to get the full duration. In fact, someone had written a CIQ app that showed the battery drain to not be linear. If I remember correctly, it went down more slowly the lower the percentage got. I'm not sure any electronics devices can measure battery usage accuracy to what you are expecting. Try running it from full charge to zero and then report back.

0 triwolf3 over 8 years ago

in my experience, i find GPS (1sec)+oHR consumes close to 5% (a little less) per hour which would project to about 20 hours. (my default backlight is at 20-30% but i dont know if that's on when i'm doing a GPS activity since my runs/hikes have all been in broad daylight)

Mine does about 9 % per hour with OHR and 1 sec. recording. No Glonass, no backlight, no navigation, no group track or other battery eaters enabled and only Garmin stock widgets. Not exactly what i was expecting as this would give me only something like 12 hours of GPS usage. Might be a show stopper for longer mountain hiking tours as don't want to charge during activity.

0 FlipStone over 8 years ago

Mine does about 9 % per hour with OHR and 1 sec. recording. No Glonass, no backlight, no navigation, no group track or other battery eaters enabled and only Garmin stock widgets. Not exactly what i was expecting as this would give me only something like 12 hours of GPS usage. Might be a show stopper for longer mountain hiking tours as don't want to charge during activity.

Then use smart recording... Why would you need the 1sec?

I did a 2hr run yesterday (2:02 to be precise, 22.5km) with GPS only, smart recording and OHR and lost 9% battery in total. Especially for walking/hiking I don't see why you would need/use the 1sec recording to be honest and especially if you really need long battery life.

Not sure if smart-recording would double your batterylife, as other factors play a role as well of course (tougher gps-environment for example) but it would at least help.

0 triwolf3 over 8 years ago

Thanks for reply FilpStone. For the moment is Triathlon season here in Europe so i swim, bike and run. Currently i use 1 sec. recording as Segment live tracking does not work well with smart recording. However, i doubt that using smart recording would bring me close to the ~ 10 % for a two hour GPS activity that your 935 has.
GPS environment should be okay here as i don't live in the alps. What concerns me, is that i swapped from a Fenix 5s which gave me only 6 hours of GPS activity usage. My old Fenix3 was rock solid with battery life.

0 Dr Phil over 8 years ago

I think we can assume that Garmin test these things with every ancillary setting either off or to it's most efficient setting. Basically a GPS device without any BT, ANT+, live tracking (segment or otherwise) etc all off. Off course I might be wrong, neither do I believe Garmin 'imagined' some numbers. But I'd also expect Garmin to have some evidence to test it's claims should it be required. How close to the 24 hrs is 'up to' meant to be? One hour? Two hours? Four hours? No idea. But then I take specifications with a pinch off salt at the best of times, hoping for the best, but never expecting it in reality.

There are too many variables in play to expect to exactly match the specs.

0 triwolf3 over 8 years ago

Fully agree philipshambrook, i don't expect 24+ hours of operation. Even 20 hours - which is 20 % down on "up to" - would be okay. Mine would currently work only about 12 of the "up to 24 hours" which does concern me. Specially as other user come much closer to estimated battery life. I do consider ask for a replacement as long as the unit is covered under warranty.

0 Dr Phil over 8 years ago

Rather than speculate how long you might get, why not try and see how much you do get?

0 triwolf3 over 8 years ago

I did that already: 3 days of watch usage (5 % per day) and 7 hours of GPS activity (OHR usage) left me with 18% battery capacity. I am technically skilled enough to understand that usage cannot be measured absolut linear, but if these 18 % would give me another 7 hours of GPS usage there is also something wrong with the watch.