CRACK IN HEART RATE SENSOR

Tramplite said:

. Consider yourself very lucky!

You got that backwards. Phil would be lucky if his sensor didn't crack and that was the norm and expected outcome.  This isn't the case. I think you meant to say you're very unlucky. 

The similar situation here. I just bought 645 less than 2 months, and use it several times, but the HR monitor cannot work over one week, and there is no solution from the supporting center, they just told you restart, reset, or upgrade your software. Too bad to experience all the process.

I noticed this as a problem yesterday. I have had my 235 for 2years. It has four little ‘windows’ and all are crazed. It is worn daily for walking, running and road cycling. I don’t even wear it in the shower or swimming. That all four have become damaged at once was a surprise and is NOT due to impact. I wonder if charging over a period causes heat induced cracking in the plastic sensor windows.

I’m guessing the watch is no longer going to be watertight if the need arises.  As it’s outside the guarantee period I’m assuming it will be a loss I have to suffer for a design defect. Has anyone had success with claiming against this fault outside the guarantee period??

I have yet another horrible story, not just about the sensor cracking, but also about the way Garmin supports their customers.

The HR sensor on my 935 started cracking after just a few months of use. As in the other cases in this thread, it was never dropped and I could also observe it was gradually cracking more and more with some time. So I sent the watch to the Garmin service center...

 I won my watch at an event and unfortunately, the organizer couldn't provide me with a receipt. I wrote to the support that I understand that this is a problem and that I'm willing to pay for the repair. 

The service center answered that they can't repair the watch, because they no longer have the spare part needed. This model is still being sold in many shops, but Garmin does not have spare parts for it? Well, after some search, I realized that it is possible to buy new casing for 935. Not like a part from someone's broken watch, but actual genuine new part. I wrote to the support that if they can't get it, I can and I'm willing to buy it at my own expense and send it to them. They answered that this is not possible. The exact reason given was "because we don't do this". 

So thank you Garmin for a top-noch product that lasted almost 6 months and for great customer-centric support. 

This is a big issue with many Garmin models and a lot of customers affected. As if it was not embarrassing enough, instead of trying to resolve the problem, Garmin is trying to make their customers carry the costs connected to issues in production causing faulty units to be sold. 

One more note. Even the new models still have the same problem. Although having known about the problem for a long time, Garmin still didn't resolve it and keeps selling faulty products like nothing was happening. See e.g. here the same problem with 945: 

https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-945/172337/945-sensors-cracking-flaking

You are right. Newer Garmin models still suffer from the same problem (which has been well known for more than 2 years now.) See e.g. here the same with Forerunner 945: 

https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-945/172337/945-sensors-cracking-flaking

Out of curiosity, will this affect the HR monitor or water resistance? Or is it just superficial.

Mine is doing this and it's making me nervous to wear it swimming!

My theory based solely on observation of my own watch and the photos of others' watches is that the heat emitted by the optical sensor is causing the cracks.  All the cracks that I've seen are directly over the sensor, not the edges nor anywhere else.  As soon as I saw other members photos of the problem, I began a strict regimen of rinsing the watch after every workout to get rid of residue, sweat, lotion, salt, etc.  I have kept it very clean, and it has not been subject to any drastic temperature changes.  However, I have worn the watch during gps runs for upwards of 3 hours regularly.  I believe that the more the optical sensors are used, the more they heat up, and then the more likely they are to crack the resin cover.  Does anybody agree or disagree?  I could be very wrong, but if I am correct then the problem is a design flaw.

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Seems highly unlikely that the heat from those leds have anything to do with it. If they would release any meaningful amount of heat they would deplete the battery in no time.

Let's say the watch would dissipate 0.5 watt directly into the plastic, which is still very unlikely to cause any measurable increase in the temperature. The watch has about a 300mAh battery, which is roughly ~1.1Wh, so the battery would last for about ~2 hours of use if it would dissipate that much heat.

This is of course all just a rough calculation, but it shows that there is no way the watch itself can heat anything up enough without instantly depleting its battery.

Seems a lot more likely that the aging of the material combined with chemicals in sweat/lotions/pools plus the mechanical forces on it cause the cracks. It's definitely a design flaw nonetheless, as these are are expected condition for a triathlon watch.

Good point.