My cycling friend has a Garmin 810 that he has bluetoothed to his smart phone to do live tracking. For a long while now, it is not working. It will sometimes start and within 15 minutes, it will stop and the message I get on my pc says sigmal lost trying to reconnect. Anyone have any ideas. My wife wants to get me one for Christmas but with this message, she would be more worried about what happened and if I was ok.
Any ideas?

Suggest you try the official Garmin 810 users' forum for info and answers :

https://forums.garmin.com/forumdisplay.php?362-Edge-810

I believe much of it has to do with the users phone. I have had an 810 for a few months now and have had zero issues with the tracking since one of the early firmware revisions.
I am using an 810 on firmware 2.70 with a Verizon Motorola droid 4. I have tracking setup with a link going to my wife and one to a co-worker who is my designated "accountability partner"

Thanks for the info.

Yep, if the phone drops the bt connection, or loses data it's toast. Update firmware and check phone settings - I rarely have a live track mess up.