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735XT problem in "cold" weather

Tokskaft
over 8 years ago
Had problems today with "temporary" battery drain on my 735XT.

This morning it was -2°C and took a bike ride to work. Had approx 35% battery left when I started.
After 25 min the watch suddenly shutdown, tried to restarted it during the ride but it shutdown seconds after boot-up.
When I got inside I once more tried to restart it, but once more shutdown seconds after boot-up. Waited approx 5 min and this time it bootet up successfully, but the battery indicator showed hardly any battery power left.
Thought the cold had drained the watch and left it running during the shower. When I checked the watch after the shower the battery had increased, and kept increasing for about 1½ hour before finally settling in at 25% power left.

The same experienced when I rode home, took a shorter route.
Before start I had 23% battery left, 17 min ride home in 1°C, result 10% battery left.
After about 10 min inside, I had 11 % battery.
40 min -> 14 %
60 min -> 17 %

Watch was mounted on the handlebars, only rode at about avg 22 km/h.

Had plans to use the watch for crosscountry skiing, but seems unlikely that the 735XT will usable in -7 to -15°C when I got problems in -2°C.
Of course I could wear it under clothes, but I bought a watch since I want to see stats during the workout, not only after.

Will fully charge it tonight and try again tomorrow, forecast promises around -2°C again.
  • 0 over 8 years ago
    Go searching in the 630 thread for posts from a year ago and there is lot of info on battery performance in cold weather. Basically, make sure to watch is above 50% battery when going out in negative weather!

    CW
  • 0 over 8 years ago
    I usually try and avoid any GPS usage if start with under 50%. Not just Garmin watches though. Have had too many times with say an iPhone that just died when say trying to take a photo at about 20% left.
  • 0 over 8 years ago
    New ride this morning, -3°C.
    100 %, 30 minute ride, 82 % when stopping activity. 95 % after one hour indoor.

    Seems likely that the power drop would be larger when the overall battery level is lower. Will do some more testing to find my minimum battery level for sub-zero outdoor activitys.
  • 0 over 8 years ago
    How long have you had your 735? Could be that the battery gauge is not quite right.

    Fortunately it is still fairly mild in the UK where I am so can't really yet offer any comparisons for myself.
  • 0 over 8 years ago
    Its normal, all devices with accumulator, (extreme: LiIon or LiPo) will not supply the full capacity if this battery is cold. It can happen even when it is cold enough, the device shows battery is empty. This is battery chemistry..
  • 0 over 8 years ago
    Agreed - this is just expected behavior. Happens with cell phones or cameras a lot when you're out skiing. It should be a little bit better with a watch worn directly on your skin, but obviously that only helps a little bit.
  • 0 over 8 years ago
    0°C morning bike ride, 38 minutes, mounted on handlebars.
    Start activity 83%, Stop 61%, after 1½ hour indoor 75%.

    Been using my 735XT since june.

    Around 20% loss of battery level feels at bit high, first ride had over 30%. But perhaps it was the windchill, headwind and speed, that played a big role in cooling down the battery.
    Not used to this high loss of capacity at temperatures just below 0°C , but at the same time i haven't used units directly mounted in as an exposed position as the handlebars earlier.