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Battery life course navigation + OHR

ellja3
over 4 years ago

I recently purchased Forerunner 945 and I absolutely love it. Just one question, tho - the specifications say that battery life w GPS is approx 36hrs. How does this change with OHR and course navigation being used? I have a trail marathon in 3 weeks and would love to use both of these features (but no music). Estimated finish time is ~6 - 6.5hrs, which is 6x less than the aforementioned 36hrs, but I just wanted to be sure (as it didn't specify OHR and map usage).

Thank you!

  • 0 over 4 years ago

    The estimated 36 hrs with GPS is with WHR. I imagine using the navigation app will have a minimal impact on battery life.  At 6.5 hrs you'll have no issues whatsoever. 

  • 0 over 4 years ago

    Ì agree with Tess that you’ll likely have plenty of battery life. However, using the map for course navigation is going to impact the battery life substantially and you will get much less than the anticipated 36 hours but still enough for the event. If I were you I’d start testing with and without map usage to get a feel just how much the difference is. And make sure your watch is fully charged before you start the event Innocent

  • 0 over 4 years ago in reply to Dr Phil

    I agree. Navigation has substantial impact on the battery life. But 6.5 hrs is no problem for a fully charged FR945.
    I would assume that it could make 15-18 hrs with navigation turned on.

  • 0 over 4 years ago in reply to Dr Phil

    Just to clarify @philipshambrook's statement.

    Having the map as the active screen is a power drain, as constantly re-rendering the screen as you move is processor (and battery) intensive.

    Having the map as a secondary screen, and just scrolling to it when you need to do a nav check (eg. at a trail junction) uses far less power.

  • 0 over 4 years ago in reply to mcalista
    mcalista said:
    Having the map as a secondary screen, and just scrolling to it when you need to do a nav check (eg. at a trail junction) uses far less power.

    To clarify, it is my assumption the OP wouldn't have the maps displayed for the entire 6.5 hr event and would be using maps occasionally as mcalista suggested. This was the basis for my minimal battery impact comment. If my assumption was incorrect, yes, there would be a significant battery drain but the OP would still be OK for 6.5 hours. 

  • 0 over 4 years ago

    My stats from a long run I did starting with 100% battery. City run.

    Distance: 38.44km / Time: 4:19:23

    Using course navigation and having the map as my main screen for around 50% of the time give or take.

    GPS + Glonass

    OHR + RD Pod and Tempe sensors.

    At the end of my run I still had 78% of battery remaining.

    So you don't have to worry. Have a good race!

  • 0 over 4 years ago

    Just tried it yesterday. 

    I got 14 hours with navigation approximatively 40-50% of the time. 

    So use it wisely. Not enough for an ultra.  

  • 0 over 4 years ago in reply to RaduVolo

    I usually get around 10 hours of battery life with 100% navigation. On my longer runs (6 hours+) I always carry a small power bank and a charger cable just in case. I think I had 10% battery left after 8 hours on my last ultra with 1 hour of running left so I recharged just in case. The watch recharges really really fast and the powerbank can be very small. I got the flat charger puck so I can have the watch on my wrist with the charger puck underneath while running.