Has anyone had an issue with a polar HRM specifically the 720, where it stops and starts at will. It is almost like it is taking some sort of interval or maybe even as if I had hit the lap button. The data is totally corrupt because it takes several seconds to “come back on line”.
I have had a situation similar to the one you describe with my S510, but only when I am near power lines.
When the battery is dying, it will just sort of reset itself, and when you look at it, it is as if you never started it. In this case, it will have recorded the last workout, but the HR data is not usually available.
When I first got my 610i I had the same problem. It turned out it was running an interval workout by accident. And the intervals were set up to be 5 secs long. Just make sure you aren’t running an interval workout. There are a LOT of options on your 720, and it isn’t so clear from looking at the watch.
This may not be your problem. It could be the powerline thing. But, I thought I would give you other options 
-Andy
I have the 720 on my P3, but I use the power meter with it, and I have no problems with ghost starts and stops, I use the older 710 on my soloist with the regular sensors and I have no problems with that either.
I have a 720 and occasionally notice the powerline problem. I found that it sometimes helps to hit the start button after noticing the loss of data on the screen. It comes back faster than just waiting. (This assumes that you are beyond the source of interference.)
I am so frustrated with my 720i that I am going to quit wearing it. It worked fine on the swim, but stopped 13 minutes in to the ride at Ralph’s last week. I did an easy 50 miler this morning, and it stopped at least three times. I used to use it as a bike computer, but it is so unreliable I replaced it with an old fashion Astrale 8.
I didn’t have these problems exactly and I don’t have the 720 but I did a reset of mine and the strange behavior stopped. Maybe a silly question, but have you tried a reset of the watch?
I’m with you…I have a 710 and am not very happy with it at all. It is just over 1 year old and I have had to send it back 2 times because of internal failures. granted they fix it for free, but that is 2-4 weeks w/ no HRM that I paid good $$$ for. I advise many of my friends who ask to look at the Timex, and if they want to drop the coin then get the speed and distance option. I am now considering selling the 710 and buying a timex HRM and an ergomo computer (http://www.ergomo-usa.com/computer.html). From what I have seen it could be alot nicer than the polar and it is wired. I dont have the power option for my 710 but with the problems I have had with the HR function I wont buy it either. Real disapointment.
Just like everyone else I am going to have to complain about my polar HR monitor also. I have the 520 with speed and cadence pickups. I have used it for less than 8 months and the only thing that still works on it is the HR functions. When talking to the tech guys I was informed that it is “normal” for the speed to change during a ride. So when it registers a total of about 7 miles on a 45 mile ride, that is NORMAL. I have contacted polar and they have informed me that even though it has a 1 year waranty on the sensors, it will probably have to be replaced at my expense $25 for each sensor. What in the hell is that all about??? I can promise you that I will NEVER use a Polar monitor again and I strongly recommend that everyone else try something different.
love my 610i. no problems here
Mine quit doing that when I turned the auto stop start off.
I had a power line out in front of the house that would stop and restart the heart rate monitor if the auto stop and start was on.
Changed that and no problems since.
I also love my S510. Two and a half years, hundreds of workouts, over a dozen races, and no problems.
I would really like to see Polar come out with something equivalent to the Speed & Distance system.
One thing I have noticed is that a lot of people on this forum who have had problems with their Polar monitors have the x20 series units. I wonder if there were any manufacturing changes from the x10 series to the x20 series.
My S710i has been working flawlessly for a couple years. I was having some problems downloading data, but the was from a weak battery. I just had the battery replaced and it’s working great. I just got a cadence sensor, and both it and my speed sensor work fine, even with the watch on my wrist. I have both set on the ‘high’ power setting.
You may want to go through the global reset function. Call tech support and have them walk you through it.
Yup, mine too. Try Kevin’s advice: turn the auto start stop off. That cured the same problem described.
Now, however, it appears my battery is gone on my 710. The symptom is: it will read my HR for a minute or so, but gradually the screen just fades out. Sound like battery? How do you replace the batteries on these things anyway?
Tony
Sounds like a dead battery. There is a low battery indicator, but I was already having some problems with mine when it came on. Polar recommends sending the entire unit in for battery replacement and testing. www.polarservicecenter.com is the one I use. I think battery replacement runs about $17, and they test everything, and warrant their work.