HPWC Failure

[carrerascott]

Well, glad I decided to keep my 15-40 Circuit when I installed my HPWC (about a year ago). Last night my car was charging, happened to look at my App and it said the car wasn't charging with 150 miles of range, and it said to check the charge cable (I forget the exact words). Went out to the garage and HPWC was dark. Check circuit breaker -- fine. Tried reset button, nothing. Popped the panel open and things looked OK (this was at 11pm) so i figured I'd hook up the 14-50 and dig deeper this morning.

Looking this morning there are melt point and burn marks inside the box. Touching what I could with a meter, I was able to tell that power is still coming in fine, going through the front fuse fine, but stops as it goes behind the box on top -- and you can see burn marks on the paper that surrounds it. A few wavy melty plastic spots there as well. The way things are melted it looks like it may have happened over time vs just a sudden blast, but difficult to tell.

Tesla has said they are sending me a new one, but just curious if anyone else has had this.

And for new owners installing a HPWC, I think it's worth it to have a 15-40 as a backup power source "just in case." Yes it's been a year with no issues, but it sure would be a pain for these few days without a way to charge (we are nowhere near a Supercharger.

 

[efusco]

Well, glad I decided to keep my 15-40 Circuit when I installed my HPWC (about a year ago). Last night my car was charging, happened to look at my App and it said the car wasn't charging with 150 miles of range, and it said to check the charge cable (I forget the exact words). Went out to the garage and HPWC was dark. Check circuit breaker -- fine. Tried reset button, nothing. Popped the panel open and things looked OK (this was at 11pm) so i figured I'd hook up the 14-50 and dig deeper this morning.

Looking this morning there are melt point and burn marks inside the box. Touching what I could with a meter, I was able to tell that power is still coming in fine, going through the front fuse fine, but stops as it goes behind the box on top -- and you can see burn marks on the paper that surrounds it. A few wavy melty plastic spots there as well. The way things are melted it looks like it may have happened over time vs just a sudden blast, but difficult to tell.

Tesla has said they are sending me a new one, but just curious if anyone else has had this.

And for new owners installing a HPWC, I think it's worth it to have a 15-40 as a backup power source "just in case." Yes it's been a year with no issues, but it sure would be a pain for these few days without a way to charge (we are nowhere near a Supercharger.

Thanks for sharing about that. I think that's the first overt HPWC burn-out/failure we've seen. I, too, have my NEMA 14-50 still active in my garage 'just in case'.

 

[andrewket]

Thanks for sharing about that. I think that's the first overt HPWC burn-out/failure we've seen. I, too, have my NEMA 14-50 still active in my garage 'just in case'.

I have a 14-50 in my garage as well, which is now primarily used for our second EV but it's a nice backup.

 

[Cottonwood]

Thanks for sharing about that. I think that's the first overt HPWC burn-out/failure we've seen. I, too, have my NEMA 14-50 still active in my garage 'just in case'.

Having a backup source for charging is very important. I have a 14-50. a Roadster HPC, and an HPWC in the garage in Boulder on a 200 Amp sub-panel dedicated to car charging. If you add the continuos current possibilities of all three, it is 40+70+80 or 190 Amps. That is more than the continuous rating of the 200 Amp panel, but I got around this my calling the 14-50 a "backup" charge point when not using one of the other two. Even though the HPC has not glitched in 5 years, and the HPWC seems to work very reliably, I like knowing that there is a backup. Besides, one 14-50 is between, and backs up, both the HPC and the HPWC!

Actually, that brings up an idea. Because I have both the R and the S in Boulder now, I should have another Tesla owner stop by and take the total charge current up to 160 Amps in the garage (throttle some of the charge rates to limit at 160 Amps total) to see what kind of Voltage drops I see. As I like to say, "If it hasn't been tested, it doesn't work!" :wink:

 

[brianman]

Agree with all the other posters -- having the 14-50 backup (on a different circuit) is a good safety net. I had my first HPWC go out at one point (which Tesla replaced with no drama) and it would have driven me insane to go back to 110V/12A charging during the transition.

 

[scaesare]

Were you running your HPWC at 80A?

 

[carrerascott]

Were you running your HPWC at 80A?

Yes

 

[araxara]

Maybe you can include a photo, so we can be on the lookout for similar looking melting components?

 

[carrerascott]

Will snap some pics in a bit, good idea.

Maybe you can include a photo, so we can be on the lookout for similar looking melting components?

 

[carrerascott]

There’s not a lot but here’s what I can see without disassembly.

Pic 1: Part of the paper liner near the top shows a small black burn mark.



Pic 2 & 3: The screws on the top right have blackened and plastic next to them on the right and under the second screw have melted a bit. You can see the screws on the left side look clean and have not melted.


Pic 4: The plastic to the right of the screws (with the sticker on it) has also melted from heat (you can see the sticker is wavy — it’s pretty much on the plastic, which is mis-shaped now). We did test and have power coming into and out of those 4 screws still, but the power stops when it goes up to the upper part of the HPWC (using a meter).

 

[FlasherZ]

Looks like a loose screw on the fuse on the right caused heat. Did Tesla replace your fuses for you or was this a factory unit with the new 200A fuses?

 

[carrerascott]

Looks like a loose screw on the fuse on the right caused heat. Did Tesla replace your fuses for you or was this a factory unit with the new 200A fuses?

Tesla replaced the fuses several months back.

 

[Lloyd]

Looks to me like the heat came from the L2 termination. Not the fault of the HPWC, IMO.

 

[carrerascott]

Looks to me like the heat came from the L2 termination. Not the fault of the HPWC, IMO.

Which is the L2 termination? The darkened screw upper right? If so, that came as is, possibly loosened over time? May not be a fault of the HPWC electronics but certainly a fault.

 

[jthompson]

@carrerascott: Is your HWPC outside? I saw several areas where rust is present and wondering if the increased resistance due tot he rust was a factor.

 

[carrerascott]

@carrerascott: Is your HWPC outside? I saw several areas where rust is present and wondering if the increased resistance due tot he rust was a factor.

No it's inside a fully finished garage, not near window or door . I don't see rust, areas are darkened by heat I think.

 

[Kalud]

Thanks for sharing, I'll check mine just in case. I also have a backup 14-50 installed

 

[FlasherZ]

Looks to me like the heat came from the L2 termination. Not the fault of the HPWC, IMO.

I disagree. Look at the screw above the L2 lug, the one that holds the fuse bracket to the terminal block (not the dark black screw but the one above it) - you can see a gap between the screw head and the bracket (unless this was due to Scott unscrewing it). This would create intense heat at 80A. It can't be 100% confirmed because of different metal thicknesses, but it looks like the most intense heat came from the top side of that terminal bracket, where the fuse bracket is attached above the wiring lug.

I suspect that when Tesla replaced the fuses, they did not get the screw torqued all the way to spec. Torque is extremely important for electrical infrastructure screws, because heat generation can work screws loose with expansion and contraction, especially at joints where there might be slightly different metal alloys meeting each other.

- - - Updated - - -

@carrerascott: Is your HWPC outside? I saw several areas where rust is present and wondering if the increased resistance due tot he rust was a factor.

Intense heat like this will accelerate oxidization.

 

[Lloyd]

Flasher is correct. Looks like the fuses were not tightened properly.

 

[Cottonwood]

Looks like a loose screw on the fuse on the right caused heat. Did Tesla replace your fuses for you or was this a factory unit with the new 200A fuses?

Tesla replaced the fuses several months back.

Given that it looks like Tesla Service created the fault, then Tesla should do more than send you a new unit, they should do the replacement or pay the cost of replacement.