Only 15h GPS in full sun with 100% battery [Instinct Dual Power]

I have a Garmin Instinct Dual Power (the Japanese version of the Instinct Solar but without PulseOX), with firmware 9.10

I charged the watch to 100% and then went for a 2 days bike ride.
At the beginning of the ride, the battery estimate was 30h with settings: wrist HR and GPS+Glonass, Smart saving, phone connected, backlight 4s.

Day 1: I have ridden a total of 8h
Day 2: After riding 7h, the watch completely discharged (and it did not record the last 2h of my ride)

1h before the battery died, I switched to UltraTrac mode, disabled the phone connection, and backlight hoping to save battery.
These changes gave an estimate of 4h remaining battery (enough to get home), but the watch nonetheless died after just 1h.
Both rides were in bright sun (as confirmed from the solar widget), but no charging seem to have occurred.

I am quite disappointed by this battery life: 15h instead of 30h, only 50% of what estimated by the watch!
Does my watch have any issue? Is the estimated battery life on your watches accurate?

Thanks for your help,
Giordano

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0 darnich over 4 years ago

If I was to do such a long bike ride I would use just GPS without Glonass. I would also use the backlight in the lowest intensity like 10 to 20%. One last thing that I would suggest in such long activities is to carry with you a power bank and the charge cables for the phone and watch

0 Gio over 4 years ago in reply to darnich

Dear darnich, thank you for your input.
I could indeed bring a power bank and charge the watch.
But why is the watch predicting 30h (as advertised with GPS+Glonass) and then only surviving 15h?

0 darnich over 4 years ago in reply to Gio

The longest activity I have ever done is a 6 hour ride with an old forerunner 235, I haven't tested my Instinct with an activity longer than 3 hours so far so I don't really know. I suspect that the prediction is based on how your watch consumed energy before it started recording a gps+glonass activity

0 sspanak over 4 years ago

If the watch is brand new, you may need to do 2-3 full charge-discharge cycles, so that the battery could get up to its normal capacity.

As of using GLONASS or not, I haven't noticed significant difference in power consumption. I got 1% battery usage per 22 and 24 minutes, for GPS+GLONASS and GPS only respectively, based on two similar 6 hour 30 minute rides. So, in the worst case scenario, my watch would have lasted 2200 minutes, which means 36 hours. The backlight was off during the entire ride. Yours should be able to perform similarly

It all depends on the conditions, of course. I have seen ~20% battery decrease in 40 minutes or so, because I was having a break under a big tree which was most certainly blocking the signal significantly. In such cases, I usually turn off the GPS, both to save battery and to prevent recording random points where I was resting. You may try that, too. Just don't forget to turn on the GPS when go back on the saddle.

If none of the above helps, then you may have a faulty battery. Sometimes, this happens too.