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Watch switches off at 4°C - normal?

Daniel_Ilg
19 hours ago

Hi,

I strap my 955 on my handlebar for road cycling. Today it switched off at around 4°C. I switched it on again but after a couple seconds it switched off again. I strapped it on my wrist and then it worked again. Manual says it should operate till -20°C.

Similar experiences? Is this normal? I mean there is a difference between 24°C between manual and what I experience...

Cheers

PS: it happened already last week at -°7 C... so it was no one-time thing

  • 0 17 hours ago

    Hmmm.
    Obviously, in the cold every battery loses capacity, so it performs worse then in summer.

    While running, I have used my FR 955 at -5 to -10 degrees C and it was ok. But of course I then warm it with my arm from below.

    On a handlebar of a bike it is exposed to the windchill directly, which might cool down the watch further.

    If I were you, I would try to wear the FR on the arm and protect it from the wind in this temperatures.

  • 0 16 hours ago in reply to Grumpy from dawn till dusk

    Hi,

    Thx for your opinion.

    Just two things:

    Windchill does only apply to Living Beings not objects.

    Empty battery was not the reason why it switched off.

    Cheers

  • 0 5 hours ago in reply to Daniel_Ilg

    Recently I've been running a lot  in ~0C for 2+ hours with no issues.

    I also have my watch on top of my layers (as I use a HRM) so no body heat or layers keeping it warm. 

    I've never had a cold weather reboot in 2+ years of usage. I've only ever had 1 mid activity reboot in all those years, and I track every day. Fortunately the activity was still recovered this one time.

  • 0 4 hours ago in reply to Daniel_Ilg

    The thing is, of course the battery was not empty. But due to low temperature the intrinsic voltage is lower. In addition the internal resistance rises with aging and lower temperature. So if the current demand rises during activity the voltage lowers aditionally.

    At a certain point the device switches off, because the wachts thinks the battery is empty. That is a safety feature to prevent deep discharge of the Lithium-Ion-Battery as it is state of the art in all the safety standards.

    So it is very likely that the device switches off due to undervoltage resulting of a aged battery.