BorgWarner 7kw PTC high voltage coolant heater

[gudman]

Hello community!
This type of heater is installed on Zeekr X/001 machines.

With the advent of cold weather, frequent cases of heater failure began to be observed.
In all cases, it’s about the same thing, an explosion of one of the heater circuits.

Has anyone here had experience researching this problem?
I would appreciate any suggestion to solve this problem!
I will also attach a file with the specification to this message.

[Bigpie]

I've updated post to attach images directly, please do this in future posts. Saves for broken posts when the image hosting site deletes them

[gudman]

OK. Thank you so much. This is my first post on this forum. I will be more careful in the future!

[gudman]

This heater is very similar to the Webasto HVH50. I saw a discussion thread here on the forum. However, I still have questions about whether a replacement is possible. But the main question is why a micro explosion of the heater spiral occurs. This is widespread. Many users have encountered this problem!

[EV_Builder]

Obviously local heat is the issue. Not good flow? To high setpoint?

[jrbe]

You might find the answer by pulling the PC board. My assumption is there is some heat transfer paste in the back of the PC board. There might be an air bubble there and other places causing hot spots.
The components may not be doing a great job transferring the heat, allowing the pcb to overheat. Could be from warping or not enough heat transfer.

Are the 2 thin traces a thermistor? If so, that should be more in the middle of the heat source - or use a thermal imager to sense the temperature and locate it in a more accurate or the hot spot.

Another possibility I see is that it looks like they kind of silkscreen carbon? between all of the traces. There might be thin spots in that process that could cause hot spots and these failures.

It looks like this could be replicated with a serpentine pcb trace heater and an aluminum backed pcb. You could go the thousand series resistor route too if you have the height. Don't forget to use proper high voltage spacing on the traces and verify in your calculations that it will work over the expected voltage range. 7kw in that small area is a LOT to make sure the heat is transferring well.

[jrbe]

Found this for silkscreen heat trace info,
https://www.heatron.com/news-and-events ... ilm-heater

[gudman]

Are the 2 thin traces a thermistor? If so, that should be more in the middle of the heat source - or use a thermal imager to sense the temperature and locate it in a more accurate or the hot spot.

As far as I know this is a ceramic heating element. It is rigidly connected to the heat exchange radiator. However, this needs to be checked further. I cannot imagine a situation in which such a local explosion could be reproduced! This is clearly not local overheating.

These photos show the reverse side behind the board with a heater. As you can see here there is a powerful heat exchanger.

[jrbe]

As far as I know this is a ceramic heating element. It is rigidly connected to the heat exchange radiator.

From your pdf, says thick film.
They could have silkscreened all the required layers right on the aluminum, no pcb required.

However, this needs to be checked further. I cannot imagine a situation in which such a local explosion could be reproduced! This is clearly not local overheating.

If it wasn't localized you would see a lot more evidence of overheating. I would say that failure is very localized.

Can you share closeups of these red circled areas? Looks like there is at least one other spot starting to fail. There also seems to be a purposeful notch in one of the elements, maybe a "fuse" point?

These photos show the reverse side behind the board with a heater. As you can see here there is a powerful heat exchanger.

It looks like a mediocre heat exchanger. Not a ton of surface area.

[jrbe]

[jrbe]

Could also be a coolant Eddy at the divider causing a hot spot from lack of coolant flow.

Is the failure always in this spot?

[gudman]

Is the failure always in this spot?

No. For many, the failure is located right at the inlet of the heater. In my first message there is a photo of such a breakdown. Yes, and you are right about the film heating element! I didn't notice this right away in the specification. However, I do not know by what method this heating element is applied to the heat exchanger.

There is speculation in our community that the heating element is rigidly glued directly to the back of the heat exchanger. And in places where there is uneven processing of the metal of the heat exchanger, local overheating and explosion occur.

However, as I said earlier, these heaters are installed on two car models. Namely Zeekr 001 and Zeekr X. So, heater failure usually occurs on Zeekr X cars. This may indicate a software error in controlling the power of the heating element.

We are now collecting statistics on breakdowns in our community in order to make at least a rough analysis of why breakdowns occur. We are grateful to you for putting forward hypotheses about the possible cause of the mass failure of heaters.

Can you share closeups of these red circled areas? Looks like there is at least one other spot starting to fail. There also seems to be a purposeful notch in one of the elements, maybe a "fuse" point?

As for the enlarged photographs of the areas. I will pass this information on to the community and ask them to take photos if possible. As you understand, this is not my heater. The photos were taken by me from the community’s Telegram channel from other people! I simply take the initiative to solve the problem.