i have a Ultra marathon (56miles) in two weeks, I have downloaded the course onto my 735 and that’s all good the question I have is, 1. How long will the battery last is I use the route but change the gps to ultra?
I had a FR735XT. In August 2017 I attempted a 102 km ultra, but had to retire at 63 km and 9 hours into the race. After 9 hours the watch had roughly about 50% battery left. Shortly after that I had my FR735XT replaced by Garmin due to display malfunction. Initially I thought that the new unit has a better battery as I was getting significantly longer periods between recharges during a normal day-to-day use. But than came another ultra, a 100 km long event in August 2018. After about 7 hours the battery was down to 30%, and I had to recharge the watch during the race with a portable powerbank. This was highly disappointing.
Now some comments to the watch configuration I used during both races:
GPS in normal mode (not ultratrac), GLONASS off.
Optical HR off.
ANT+ footpod and tempe sensors paired and connected. Other sensors paired but not connected.
Bluetooth on, connected to the phone, with livetrack on.
No Connect IQ datafields.
Course uploaded and course navigation enabled.
As far as I can tell, although I used two different units for the two races, the configuration was the same on both occasions. The only obvious difference was firmware version. I can't remember the version I had a year ago, but last August I had 9.30. Normally I would attribute the poor battery performance during the second race to inferior battery or battery malfunction, but the thing is that during non-activity I get excellent battery life. When not doing GPS activities I get as much as 14 days between recharges, with bluetooth on, which is actually better than Garmin's specification, and much better I had with my previous unit. So my theory is that either latest firmware causes excessive battery drain during timed activities, or I am missing some setting.
I never used ultratrac, except some test runs. The accuracy of ultratrac is not satisfactory for me, and unless you really want to stretch battery life, I'd advise against using it. I don't even know how course navigation performs during ultratrac. Accoring to Garmin with ultratrac you can expect about 24 hours of battery, but realistically I would not count on that. I have not seen any significant battery impact when using course navigation against not using it, so go for it.
Other interesing remarks: Long courses take a very long time to load, so make sure to start loading your course at least 15 minutes before race start. With very long courses I noticed that turn alerts appear with a delay, although not to a degree to make course navigation difficult.
Well, these are my comments regarding using the FR735XT for an ultra race. I hope you find them useful. Good luck on your race.
I used my 735XT for 55 mile ultra in June. The battery lasted pretty well in GPS mode. I didn't want to use ultratrac, as wanted to have an accurate course profile after the race as I'm geeky about it! I carried a small portable charger and when the battery got to about 35% (which took around 5-6 hours) I plugged it in to that and put it in my pack for about half an hour, which fully charged it. Then off I went again!
The watch is certainly up to the challenge with a little help halfway. I'm 100% sure ultratrac mode would last easily 24 hours.
