Ultramarathon and battery life

minhboo According to the specs, you can get up to 14 hrs GPS without music. So, unless you have a way to recharge the watch during this marathon it's not going to last.

You could use ultratrac GPS mode to increase battery life, but would affect track precision.
if it's not a problem to you, this is the solution, without the need to recharge during the race

For more than 10hours of gps mode I would not rely on the battery life. You should take a charger or put into ultratrac as mentioned. I have experience, that with ultratrack it can last for approx. 20hours at least.

ultra track is mega sh!t I think you will need precise mileage counting during race (aid stations etc) so I would recommend you small power-bank. I also tried run while watches were charged on my wrist and it's possible... not comfortable but possible. Good luck :)

Thanks for the replies! Yes - I think I will try to "run" while charging; might be a bit uncomfortable, but worth the accuracy. Will report back!

Hi all,

After almost 6 months of wearing it, I am quite happy with the 645M (despite the initial hiccups) and haven't had many problems with the watch so far.

In about 2 months, I will be doing a 50milers trail marathon, which should take me around 16/17 hours. I plan to put the watch on the lowest battery settings (gps only, no bluetooth, smart tracking, etc...)

Has anyone attempted to stretch the battery life this long?

Thanks!

Hey minhboo , how did your race go with the watch? I have a 50 coming up and have the same concerns about battery life with the 645M. I'm curious if you ran with a charger or changed the settings?

hi chrlewis !

Race is this weekend - the 9 dragons in HK!

I have done some training with a charger, and not very comfortable, but it charges quite rapidly; so im thinking of just stashing the watch in my vest while it's charging (with the activity still running).

I will also change all the settings - no bluetooth, ultratrac, OHR off.

Hope this helps and good luck on your race!

Ran a 50k traing race in 4:28 hours and lost 41% battery with 1sec recording, stryd and tempe connected. HR from p*lar OH1 via Bluetooth

For those who are interested in an update,

Went into the race this past weekend, not really knowing what to expect from the watch...so, just changed all the settings to a minimum.

GPS: Ultratac
Recording: Smart
No Bluetooth
No Music
Facewatch - only one - the 1Race
No other devices connected to the watch

50km and 10hours laters - watch still had 46% on it!

Ultratac is not that bad as I was out in the open mountains of HK, but not accurate enough to tell me the next checkpoint.

Hope it helps!