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Intermittent connection between HRM-Run strap and a watch

AK_19_08
over 5 years ago
Hi everyone,

I have an issue with Garmin 935 and HRM-Run strap. Connection between the watch and the strap is not reliable and constantly dropping out during activity.
Some runs are OK, connection stays stable, so both devices work well. During some activities connection stays for sometime (say 10 minutes) but become intermittent for the next 10 - 20 minutes before becoming stable again. During some activities it stays intermittent (see screenshots attached).

The watch and the strap had been working fine for about 6 months before problems started a few months ago.

I have changed the battery in the strap but it didn't solve the problem. So, at present I don't use strap and rely on HR sensor in the watch.

Has anyone have the same problem before? Any ideas what it may be? Problem with the watch or with the HRM-Run strap. ciq.forums.garmin.com/.../1479098.png ciq.forums.garmin.com/.../1479099.png ciq.forums.garmin.com/.../1479100.png
  • 0 over 5 years ago
    My first suggestion would be to check the battery, but from your post, you have already done that. It might be worth looking at the battery contacts.

    You may want to try tightening the chest strap.

    Over time, salts from sweat can accumulate in the strap and cause issues. Regular washing in warm water with a mild detergent can help dissolve these salts.
  • 0 over 5 years ago
    My first suggestion would be to check the battery, but from your post, you have already done that. It might be worth looking at the battery contacts.

    You may want to try tightening the chest strap.

    Over time, salts from sweat can accumulate in the strap and cause issues. Regular washing in warm water with a mild detergent can help dissolve these salts.


    Thanks for reply to my post.
    It seems that I have done all what you suggested.
    What I haven’t done so far is applying any electrical contact cleaner. But looking at the battery contacts: they are clean. I already tried bending contact a little to make sure battery touching them well.

    What puzzle me the most that problem is not consistent. Sometimes everything works fine. This leaves me a little hope that it may be battery contact.
  • 0 over 5 years ago
    It might also be the strap. Have you followed the care instructions for the strap?
  • 0 over 5 years ago
    It might also be the strap. Have you followed the care instructions for the strap?


    Yes, I followed the care instructions. But there is not much to follow: just wash strap every couple of weeks. Or is there anything else?
  • 0 over 5 years ago
    From the manual_
    • Rinse the heart rate monitor after every use.
    • Hand wash the heart rate monitor after every seven uses, using a tiny amount of mild detergent, such as dishwashing liquid.

      NOTE: Using too much detergent may damage the heart rate monitor.
    • Do not put the heart rate monitor in a washing machine or dryer.
    • When drying the heart rate monitor, hang it up or lay it flat.
    The elastic straps do deteriorate and require replacing. I usually get about a year to 18 months before I have to replace a strap. Fortunately I have the one with the separate module so I need only replace the strap.
  • 0 over 5 years ago

    [/LIST] The elastic straps do deteriorate and require replacing. I usually get about a year to 18 months before I have to replace a strap. Fortunately I have the one with the separate module so I need only replace the strap.

    How do you know that your strap is up for replacement? Do you see HR reading drop? Or something else?
  • 0 over 5 years ago
    The HRM-Runs with the intergrated module are supposed to be less susceptible to the salt issue than those with the removable sensor.

    The normal indication of strap issues is an unfeasibly high heart rate (as the salts can lead to stray static electricity currents in the strap), but other problems can occur.

    I haven't seen huge numbers of people complaining about salts with the newer intergrated module.
  • 0 over 5 years ago
    Consistently erratic readings are enough to have me change the strap. Usually I have few problems so anything out of the ordinary for a couple of activities sets off alarm bells. Irrespective of whether or not I've had a warning that the battery is getting low, the first thing I do is change the battery. If the problems persist, I change the strap.

    For indication 18 months equates to about 750 hrs of activity using the chest strap.
  • Former Member
    0 Former Member over 5 years ago
    AK_19_08, would you mind uploading the original fit file here so we can have a look at it

    these are no connection drops, because your optical heart rate should kick in and take over
    or you turned off your OHR-WHR ;)
  • 0 over 5 years ago
    AK_19_08, would you mind uploading the original fit file here so we can have a look at it

    these are no connection drops, because your optical heart rate should kick in and take over
    or you turned off your OHR-WHR ;)


    Excuse my ignorance, what is “the original fit file”? If you direct me, I will send it.

    I really think that it is the connection between my watch and the strap dropping off as all data disappear (vertical ratio, stride length , etc) for a period of time. See, the screen shots attached to the first message. Also, sometimes I get a message on the watch that “external sensor connected” during the activity. Similar type of message, as at the beginning of activity.