Polar T31 Coded Chest Transmitter and Elastic Strap

Worked better than expected. I love this device. I wish that it came in different sizes. I only saw the one size and it fits snug.

I bought this "NEW" in June of 2016. In July 2018 it started not broadcasting my heart rate for about the first 20 minutes every workout until it gets warm and a little sweaty, then it starts working, slowly coming down from 220 indicated BPM or so to what my actual heart rate is. (my heart doesn't go 220-bpm) There are 25 spinning bikes in the room, it does the same thing ON ALL 25 BIKES, EVERY SINGLE BIKE SAME THING, so it is not the heart rate indicator on "THE BIKE"! I have used Polar HRMs since the 1990s maybe 1980s? Within the last 5 or 10 years or so the battery life has gotten shorter and shorter. Maybe mine sat on the shelf in some department store or in some bike shop for the first 5 or 10 years of its life before I bought it "NEW" from Amazon? I honestly don't know what to do. I have to buy another one because all the equipment i use at the health club (where i work) is Polar compatible. Maybe the non-coded one is cheaper and will last longer, we will see.This is a follow up, March 2019. I tried an experiment for the last month or two. I run the transmitter under water in the sink at the health club for a second or 2, just to make it wet. I put it on wet and i go into the spinning room and it works perfectly the second i turn on the heart rate indicator on the bike. All the way through the workout it works perfectly. SO if you have one that stopped working or works intermittently, run it under water and put it on to see if that makes it work. Maybe it is an indicator that the battery is getting low but this saved me from buying a new one at this time. Good luck!

In my experience these Polar T31 transmitters work great... when they have a good battery in them. The problems come up when you buy a "new" transmitter which may have been manufactured 2 years ago? 5 years ago? 10 years ago? Since there is no manufacturing date code on the product you don't know when it was manufactured. Also you don't know if it sat in a warehouse at 120 degrees or other less than ideal battery storage temperatures for all those years. The result is the "new" transmitter may work for a week, two weeks, or two years.That said, it is pretty simple to open one of these with a knife and replace the battery (CR2032), and seal it up with some plastidip or flex-seal. The signal will be good for 12-18 months and works fine with most cardio equipment I have seen in gyms over the years. In fact it's not unusual to see my heart rate show on the machines on either side of me while I'm working out at the gym.I have a Polar 610i wrist monitor I have been using for 20+ years. In that time I have had to purchase three or four replacement T31 coded transmitters and the factory battery has never lasted more than 12 months using it for cardio workouts 3-5 times per week. So I replace the factory battery and typically every 15-18 months thereafter. When the cardio machine has problems receiving the signal I know it's time to replace, even though the wrist monitor is still recieving no problems. Eventually they do stop working and I need to buy another. This purchase (2/1/25) replaces one I purchased around 2016 which has had new batteries installed 5 or 6 times.If you don't want to replace batteries consider some other heart monitor, or spend $35 every time the battery dies.

I've been using this strap at the gym with a LifeFitness elliptical and treadmill. When I first used it, it was excellent. I just hopped on the elliptical and started the workout and the strap automatically kicked in and sent information to the machine. I didn't even have to sweat a whole lot. Same thing with the treadmill. Throughout my roughly 1 hour workouts for about 1 week, it worked perfectly.A few days ago though I started noticing problems with the heart rate reading on the machine. From the usual 158-165 BPM I try to stick to, it all of a sudden goes to like..130 or 140 or even 120 out of nowhere. Since the machines I'm using are basing the strain of the exercise on my inputted target heart rate (160), when there's a sudden drop like that, the whole workout gets all screwed up (the resistance on the elliptical skyrockets, or the incline on the treadmill). Sometimes the reading just flat out shuts off and the machine tells me it needs my heart rate.I'm pretty sure I've ruled out the possibility of interference, as for that first week when the strap was working just fine, there were sometimes people right next to me with a polar wrist strap on. No interference. On top of that, it's happening when I'm at least 5 machines away from anyone else.Also, I don't think the problem is with the battery either. Before I made my purchase, I read that the sensors are very sensitive to wetness. Everytime I'm done with the strap, I take it off and dry it well, then place it in a dry area until the next day.Lastly, if it were a problem with the machine itself then why is it happening on multiple machines, of two different kinds?I'm compelled to believe that it's a faulty product.