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battery change for t31 coded polar HR transmitter

kjg's picture

I am confused as to whether or not the transmitter battery is changeable in the T31 or not!

It looks like it should be (has the slot on the back for a quarter) but when I turn it I can't get the back off. I have read that the Polar transmitter do not have a changeable battery but I think that may be refering to the older style.

If anyone has done this please help! I really don't want to pay $30 bucks plus s&h and be without my monitor for 3 weeks to exchange it!



Spoke to the lady at the service center and I do have the wearlink (with the flexible strap) I was confused because it said 31 on the back and the place on the front where it should say wearlink is worn off! So it is in theory user changeable. I can get the disc to turn but the prying off/out is the problem, she said they have a special tool for that - but will cost me $11 plus s&h in both directions. They are just down the road from me but only open 9-4 so no way to drop it off.

I am still tempted to try the prying option.

Since it is coded, if you buy a new one how do you make them talk to each other???


roadskater's picture

Perhaps Turn then Pull to Remove Heart Rate Monitor Battery

Hi and good luck with this. If there's a battery cover I'd say you should be able to swap this out. Old style T31 heart rate monitor transmitters did not allow changing the battery. I believe eebee has one and she may be able to look to see if there's any kind of battery compartment door. Regardless, it is likely not just a screw-out but turn left then pull out or pry out or turn upside down drop out deal. Good luck.

On my old T61 there was no battery compartment door. I hacked my T61 HRM strap open and took photographs so maybe I can put some of those up later. If you decide to try to hack it open, go in from dead center on the FRONT, not from the back, and work from the center outward. This is ONLY for those who don't want to send it back to Polar and wait while buying another transmitter anyway. My hack did NOT work as I believe the problem was other than the battery. My plan was to replace the battery (it is a size not found at most pharmacies but available at battery stores locally.)

I ended up getting one of the new Polar WearLink transmitters that has a replaceable battery and more lightweight elastic and less plastic, plus it is designed for easy battery replacement. I have been very happy with the WearLink transmitter so far.

The Polar accessories don't seem to go "on sale" often, and they are somewhat difficult to get in my area, but you might get a good deal on eBay. I'll put an ebay search in below and some links to the best price I find among affiliates below (if any), but they're likely to be higher than on ebay. On ebay, in my opinion, look for at least 10 feedbacks from buyers and an overall 99.5-100% positive rate (1 negative per 200 transactions). Good luck and please let us know what you end up doing.

roadskater's picture

Ruin it Yourself

I'm of the do it yourself school, even though that is sometimes better known as ruin it yourself. With my T61 there was no way I was sending it back to Finland. Not going to happen. And because of the way the heart rate monitor strap looked, I wasn't sure that would even fix it. I searched the internet and found some comments but no photographs. I decided to just hack in from the front and I would at least have the satisfaction of seeing what was inside. Well I got my satisfaction, and some photos, and then got a new WearLink when my fix didn't work. I can't be sure I didn't ruin it, but don't think I did. I just think the contacts were broken from the sensor on each side. Anyway...


I'd try unscrewing the back until it gives resistance, then I'd try an X-ACTO or similar razor-thin blade knife to get the back off. Then if I ruined it, I'd hack it open, get the replacement battery (Batteries Plus had them I think), and get some RTV Black Silicone to put it all back together.


But smart people might just pay to have someone else do it!


Regarding the WearLink, T31 and T61 coded Polar heart rate monitor straps, my understanding is the watch picks out the coding when it boots up after you press the button to go into heart rate monitoring mode. I think it picks the code of the strongest heart rate monitor strap it finds for that session, which is why you should step away from your training partner when you boot up if they wear a coded Polar strap. Usually it is not a problem, but perhaps if you were next to a strong batteried strap and yours was weak, you might be reading their numbers instead of yours. But I'm not sure. I do know that coded straps are nice for avoiding crosstalk.


Do you use the WearLink strap with your Garmin Forerunner? Do you also wear a Polar HRM on your wrist? Some other combination?


Meanwhile, in the Office Space department, check out the sexy upgrades of someone stole my stapler options on the surprisingly sleek X-ACTO website.

I got it

I was able to open mine using a torch. I heated up the body of the transmitter surrounding the battery door. Be careful not to melt the actual housing. You might be able to do this with a lighter, too. The goal is to heat up the body of the transmitter and not the battery door so that the transmitter expands while the battery door remains the same size. Then I was able to unscrew the door with a quarter. Hope this helps someone. -Jeff

I don't see why it couldn't

I don't see why it couldn't be replaced, no battery lasts forever so all the slots for batteries should allow easy battery replacement.
skatey-mark's picture

wearlink battery replacement is possible, but not intuitive

Polar certainly doesn't make things obvious, but you can change the battery on the wearlink without resorting to heating it up, or whatever. First, when you rotate the cover using a quarter, it doesn't turn very far. Don't try to force it to turn more -- you'll just mangle it. It doesn't unscrew so much as it simply un-latches. Unfortunately, there is nothing to grab onto to get the cover off once it's un-latched. What I do is get a pocketknife and stick it into the crack and gently pry the cover off. You don't have to stick the knife in far -- you're just trying to get it to "grab" the cover a bit. It should pop right off... I'm not sure about the T31, but the T61 transmitter was not made to be user-serviceable. The only way to replace the battery was to send it to Polar. That hasn't stopped me (or others) from trying though. As far as I know, though, nobody has successfully changed the batteries in those transmitters without killing the transmitter in the process. Here is a link describing my attempt: http://roadskater.net/polar-t61-hrm-transmitter-battery-replacement-post... After killing my T61, I just bought a wearlink transmitter. So I don't need to do anything extraordinary to replace the battery anymore. Just pop the cover off, as I described earlier. - SM -

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