DIY to the rescue: Polar HRM strap battery replacement

[Kickit]

Until I get something better, I decided to revive my old Polar HRM that I haven't used in a few years. The trouble was dead battery in the watch. So I went down to the CVS. I ended up buying a two pack of 2032 batteries and it's a good thing I did. After changing out the battery in the watch, the chest strap transmitter was also dead. The trouble is it's the T31 model strap that is sealed up molded in plastic. I figured it's dead already so I might as well take a crack at fixing it. It worked out well so here is what I figured out:

1. Take a razor and cut around the edge of the larger oval surrounding the Polar logo. Cut along one edge (I suppose you could go ahead a cut all the way around). Don't cut the middle else you might damage the circuit board or components.



2. After cutting it open like a clamshell, you'll see a black plastic cover in the front.



3. You'll need to remove the three small screws in the back to remove the cover and expose the battery.



4. Remove the plastic cover and the old battery. Don't lose the gold leads.



5. Replace with a new 2032 battery.



6. Put it all back together. Use some RTV silicone sealer around the cut edges to seal it back up and tape it to hold in place until it drys.



7. Go have a great workout with lower lows and higher highs.

Now back you our regularly scheduled program...

[99trek5200]

Nice job. I may have to do that soon too as my HRM has been doing funky things, particularly when it is cold.

[DonkeyMan]

I've got one of the 500 series, 510 i believe, that's been out for years now. Just sitting in my drawer collecting dust. I've got nothing to lose with your DIY tip. Thanks again.

[serpico7]

Pics are no longer up, but I cut mine open with a Dremel: thread

[MR_GRUMPY]

Great idea. I've got an old dead one that I kept (I never throw anythig away), that I will try this on. My current one has a year or two left in it.

[laffeaux]

Thanks!! My Polar chest strap died this past summer, and I've been riding without it ever since. I'll give this a try very soon.

[messyparrot]

Thanks for the thread, the pics are nice and clear!

Nice job!

[Tugboat]

Or you could buy one of the CS600s which comes with a user replaceable battery in the WIND Wearlink strap.

[MR_GRUMPY]

This idea is "slightly" cheaper.

[99trek5200]

I tried to do mine, but to no avail. One thing that was not obvious in the pictures when I first read the above is that both the front and back of the cover must be cut to access the screws and and remove the black cover. I think I scratched the back of the circuit board trying to open just the back.

Oh well. For $31 I found a new one on E-bay and the 2032 battery will fit in my cycle computer.

[Fredke]

Originally Posted by Tugboat

Or you could buy one of the CS600s which comes with a user replaceable battery in the WIND Wearlink strap.

They also make a non-WIND wearlink with a user-replaceable battery in case you don't want to spend over $300 on a new HRM. But it's still almost $60.00, so there's merit in knowing how to cut open an older transmitter and replace the $0.50 battery.

[Bill70J]

I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.

[murbike]

Oh, man. I think I threw my strap away a couple of weeks ago during a cleaning frenzy.
Damn. Should have known someone here would know how to fix it.

Oh well. Live and learn.

Speaking of HRM, does anyone have any experience with the Timex HRMs?

[cpark]

Thanks!

[Mr Wood]

Doesn't Polar send you a new one if you send in your dead one?

[rbart4506]

Originally Posted by murbike

Speaking of HRM, does anyone have any experience with the Timex HRMs?

Yes...Did not have success...Lots of crosstalk and erratic readings....Hence the reason I'm using a Polar now...

[velodog]

Originally Posted by Mr Wood

Doesn't Polar send you a new one if you send in your dead one?

Yes, if you send a check also!

[jjspike]

Great post as it provides the motivation to attempt the fix.....

[Adam_SF]

The same process works for replacing the battery in the cadence sensor too.

[murbike]

Originally Posted by rbart4506

Yes...Did not have success...Lots of crosstalk and erratic readings....Hence the reason I'm using a Polar now...

Thanks, I'll get another Polar. I liked the one I had, so if there is no overriding reason to switch, I won't.

[foz]

Originally Posted by Bill70J

I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.

Have you still got those pics? My T61 doesn't have much life left, and I want to try and change the battery myself. Any tips before cutting it open would be appreciated!

thanks

[Kickit]

Followup:

The strap only lasted a few weeks before the silicone started to give. So I would recommend putting some heat shrink tubing to hold it together, that way the silicone is just there for sealing. I ended up getting a new Polar HRM so that I could download the data.

Here is the cost breakdown from Polar:

Transmitter replacement:
T31 (with trade-in) $24.95
T31C (with trade-in) $30.95

[yakobo]

Washing the contact points on the strap with warm water and soap does wonders for these straps as body oil builds up and interferes with transmission. Also, on the wearlink model, cleaning the snaps with some alcohol on a Q-tip will often bring it back to life.

[hhssss]

hi. my 720i coded t61 transmitter just died. can you post pics? i'd like to attempt to replace the battery myself ...

Originally Posted by Bill70J

I have a Polar 720i with the T61-CODED transmitter (N2965). I saved this post knowing I would need it some day.

My transmitter went dead yesterday, so I attempted to do the "clamshell repair' described here. Having just gone through it, I must say the appraoch is slightly different, plus the replacement battery is No. 2354 vs. 2032.

If anyone is interested and wants to try this with a T61, let me know and I will post pics.

[Saibots]

Thank you so much Kickit for your detailed instructions!

I have a Polar T61-CODED transmitter. I used the same method (steps 1-3) as described above to access the circuit board. For the T61, there are two small screws on the circuit board to remove. However, the T61 transmitter has two gold parts of the circuit board which extends partially into the straps. With a flat head screwdriver, you can work it in between the plastic strap and the gold portion of the circuit board to pop out one side of the circuit board. Once that is accomplished, the CR2354 battery should be accessible. Since batteryspecialists.com has them for 5.99 with free shipping, I am ordering the battery from them.