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New Forerunner 935 has a huge GPS mistakes

Bough a brand new Forerunner 935 yesterday. As it had battery charged, went for a running in an hour, along with proven Endomondo on a cell phone. Run for 35 min slowly in a park. While endo shown exactly 6 km, watches registered crazy 3.74 km. How come?!?!?

This morning run by car with the same devices. Endo tracked 6.7 km, while watches 6.1 km. Again :(

Next time changed navigation from GPS to GPS + Glonass and tracked walk. Also updated software from 8.00 to 8.99 (latest beta). Received endo 860 m and watches 1000 m.

I trust endo as I verified its routes multiple times including tracks with known (official) distances.

Should I now return watches to the shop or do some other magical things to start it tracking through GPS properly? I didn't expect such bad tracking for almost $600 new top device.

Please assist.

0 Browner40 over 7 years ago

Are you allowing the watch to fully find the GPS signal before starting your activity? The colored band around the outside of the watch face should go from red to yellow, and then finally to green when it has fully locked on to the GPS signal. With a new watch that was built and calibrated in the US, it will probably take it a while to fully map out where it is(I'm assuming not in the US due to km). You probably need to just let the GPS signal soak for a while. Turn on the running app(don't actually start it) and just leave it with a clear view of the sky for 10-15 minutes before you start your next run. If this doesn't fix it, you might have just gotten a lemon. Call customer support and they will sort you out(They are fantastic).

0 tundracamper over 7 years ago

What was noted above. First time I used my FR935 it took about 5 minutes to lock onto GPS signal. Second time it just took seconds.

Compared to my iPhone on a route I run very regularly, the FR935 is within about 0.05 miles over a distance of over 4 miles. I don't know what is the exact value as my iPhone is never exactly the same twice.

0 Dr Phil over 7 years ago

Might be best to read the manual before your next run, paying particular attention to the first 3 points on Page 1. If you are operating the device correctly, contact GARMIN Support.

0 karlw2000 over 7 years ago

Also if you post a link to your run or walk, we could very easily see a possible problem.

0 WillNorthYork over 7 years ago

Also, sometimes the watch will say GPS is ready (green ring) when it really isn't. If you look at the (instant) pace field, it might be changing wildly at this point, even if you are standing still. I like to wait until the pace settles down to "zero" before I start running. It also helps to sync regularly to reduce the amount of time it takes to find satellites.

0 FlipStone over 7 years ago

My habit, I usually put it in the window when putting on my running gear and it always gets a fix (green ring) quickly there... After that I slowly warmup/walk a bit with the fix still there and then go running. Never had an issue here.

You have to at least wait for the green ring but preferably a bit longer (say an extra minute or so) for the signal to be really ok. Still, if you have many high buildings, or electricty plants, next to your route this would mess with the signal of course.

btw, in my experience glonass doesn't add much and I leeve it disabled by default..

0 nmyeti over 7 years ago

I have a similar approach as flipstone. Put on my HRM-Run and start the activity. By the time I'm actually ready to run, the GPS has had a green ring for a few minutes. I've never had any GPS issues when following this approach.

0 Takhir over 7 years ago

Seems that was my fault. After synchronization with satellites my test run happened successfully. I've waited a bit until GPS shown green circle, run the same route I've made in the beginning in the forest - and all route has been mapped onto maps successfully. I couldn't compare to Endo due to hot weather (didn't want to bring cell phone along), but apparently I will not return watches to the seller. Thank you everyone for replying, highly appreciate your support, guys.