garmin 935 battery life on ultra using a gpx

If you were also carrying your phone make sure it's Bluetooth is off otherwise the watch and phone will be constantly communicating. I turn Phone off from the watch just so it doesn't even try.  Go look at the backlight settings and make sure it isn't coming on all the time, if you have a daytime event or nighttime with headlamp then you probably don't need the backlight anyhow, https://www8.garmin.com/manuals/webhelp/forerunner935/EN-US/GUID-C9A5E731-8826-4AD0-8087-F6E2EAC625D6.html. 

Okay Thankyou for the reply , so maybe in the future, I could disable them two options ie Bluetooth and phone and notifications and adjust the backlight to off . I may ditch the heart rate belt to save a bit of device resources which may save a few % battery I reckon ..will have to look into the gps setting I have got it on - it’s data recording.. I think the main issue was I using a fairly big route gpx at the time . Will try to test it again next time I do a long event 

Well if you ditch the HR then also turn off the Optical HR. I don't know which one draws more power. There is also the charging enroute, I have one of the charging docks, it fits under the watch on my wrist and then plug into USB battery between bag drop aid stations. Look on amazon for "garmin 935 charging dock". On GPS, Every 1 Sec recording seems to take just a bit more energy than Smart. And I use just GPS (not glonass or galileo), anecdotal reports are that adding the other satellites doesn't really help, but is higher battery drain.

Okay then , as you know on the 935 the charging position, will mean the device will need to taken off the wrist and connected to power bank while mid activity. Question is ? Will my run that I am doing stop once my device detects a power source , because in the Garmin 935 once it detects a power point of sorts the screen displays its battery percentage. Will it still keep recording my run once I have added the cable and power source and have it stowed away . 

Yes. 935 is actually in a better situation than Fenix 5 in this case. Official word from Garmin is here, 

, https://support.garmin.com/en-PH/?faq=SWQSMeMTsJ9GRBx3iOmSD9.. and for 935 it says "retains full functionality"; for Fenix 5 you have to change the USB Mode to "Garmin" from Mass storage. The top 1/3 of the display may show the percentatge when you plug in the USB, but when you arrow up or down to other displays then it will go away but still charge.

That’s awesome ! That is good to know for future events . Say if I do a 100 mile ultra , not quite there at the moment , as only dabbling with say  50 or 60 mile events Thanks for the advice 

Try it out around the neighborhood or long runs even if you don't need it, just so you are comfortable doing it on race day. 

Yeauh I will Thanks , main thing is keeping my Dwmaps Running,with the trip computer , this may solve it anyway thanks Buddy