PCS failure on 2018 M3 LR 18k miles - and maybe a failed mobile connector too?

[4ntm4n]

My 2018 M3 LR (18k miles) stopped charging and I'm not sure what to do next.

For 5 years I had been using a 15amp circuit to charge the car with the mobile connector.

A few weeks ago I had a dedicated 30amp circuit installed, and it worked well for ~11 days. On that 11th day, after coming home and plugging the charge cable in, I received a notification five minutes later on the app that charging suddenly stopped.

I didn't think much of it, but the next day I noticed the green light on the mobile connector was off. And then I noticed the 30amp breaker was tripped. I reset the breaker, but it tripped immediately. I unplugged the cable from the car, reset the breaker, plugged in the charging cable again, and it tripped immediately. I tried setting the charge rate to lower amps, but it still tripped. I then tried switching the mobile connector from the new 30amp circuit to the 15amp circuit I had been using for 5 years. The 15amp circuit didn't trip, but lights on that circuit dimmed and the car showed an error.

I drove to a supercharger for further testing. It wouldn't charge on 2 different stalls and I got an error.

I opened a service request, they did a virtual diagnosis, and I received an estimate for $2.4k to replace the PCS.

After in-person diagnosis, the technician said "Found phase A in the PCS is faulted and preventing full charge rate." They said the vehicle charged on a known good high power wall charger at 32amps but not 48 amps, and that it charged normally on all wall connectors and mobile chargers at the shop. They also said it didn't fault while supercharging (not sure if they're referring to the logs of when I tried supercharging or when they tried supercharging while it was in their possession). They noted that in addition to the PCS failure, my mobile connector could have gone bad, which could explain the 30amp breaker at my house tripping.

The shop said that if I'm okay with charging at a lower rate, I don't need to replace the PCS at this time.

I'm okay with charging at less than 30amps and would probably defer the $2.4k to the future and pay just the diagnostic fee for now.

Questions I'm thinking about:

1. Why is the vehicle charging at the shop, but not at my home on 2 different circuits nor at that supercharger I tried using before bringing it in for service? (Perhaps my mobile connector went bad, but why didn't it charge at that supercharger?)
2. Did they perform some sort of software or hardware reset which could have theoretically enabled the vehicle to charge again at their shop? (I asked them this question two days ago and still waiting for a response.)
3. Did both the PCS and my mobile connector coincidentally fail at the same time? (Assuming the mobile connector went bad, did one failure cause the other?)
4. Did the new 30amp circuit cause the failure, or just expose a PCS issue that had already been happening? (The straw that broke the camel's back)
5. Should I retake possession of the vehicle and try charging at a supercharger, and if that works, try charging at my home again?
6. The car has been off a charger for 2 weeks now (38% battery currently) and is still in the shop. Can this harm the battery?
7. Should I bite the bullet and pay the $2.4k to get the PCS replaced?
8. If I get the PCS replaced, and the mobile connector is indeed bad, is there any risk of a bad mobile connector harming the PCS?
9. And of course, why isn't the PCS considered part of the high voltage battery (for warranty purposes)? I'm at only 18k miles, but past the 4 year basic warranty point.

I guess my question to the forum is, what would you do in this situation, or, is there anything I'm missing or not thinking of?

Thank you.

 

[stopcrazypp]

My 2018 M3 LR (18k miles) stopped charging and I'm not sure what to do next.

For 5 years I had been using a 15amp circuit to charge the car with the mobile connector.

A few weeks ago I had a dedicated 30amp circuit installed, and it worked well for ~11 days. On that 11th day, after coming home and plugging the charge cable in, I received a notification five minutes later on the app that charging suddenly stopped.

I didn't think much of it, but the next day I noticed the green light on the mobile connector was off. And then I noticed the 30amp breaker was tripped. I reset the breaker, but it tripped immediately. I unplugged the cable from the car, reset the breaker, plugged in the charging cable again, and it tripped immediately. I tried setting the charge rate to lower amps, but it still tripped. I then tried switching the mobile connector from the new 30amp circuit to the 15amp circuit I had been using for 5 years. The 15amp circuit didn't trip, but lights on that circuit dimmed and the car showed an error.

I drove to a supercharger for further testing. It wouldn't charge on 2 different stalls and I got an error.

I opened a service request, they did a virtual diagnosis, and I received an estimate for $2.4k to replace the PCS.

After in-person diagnosis, the technician said "Found phase A in the PCS is faulted and preventing full charge rate." They said the vehicle charged on a known good high power wall charger at 32amps but not 48 amps, and that it charged normally on all wall connectors and mobile chargers at the shop. They also said it didn't fault while supercharging (not sure if they're referring to the logs of when I tried supercharging or when they tried supercharging while it was in their possession). They noted that in addition to the PCS failure, my mobile connector could have gone bad, which could explain the 30amp breaker at my house tripping.

The shop said that if I'm okay with charging at a lower rate, I don't need to replace the PCS at this time.

I'm okay with charging at less than 30amps and would probably defer the $2.4k to the future and pay just the diagnostic fee for now.

Questions I'm thinking about:

1. Why is the vehicle charging at the shop, but not at my home on 2 different circuits nor at that supercharger I tried using before bringing it in for service? (Perhaps my mobile connector went bad, but why didn't it charge at that supercharger?)
2. Did they perform some sort of software or hardware reset which could have theoretically enabled the vehicle to charge again at their shop? (I asked them this question two days ago and still waiting for a response.)
3. Did both the PCS and my mobile connector coincidentally fail at the same time? (Assuming the mobile connector went bad, did one failure cause the other?)
4. Did the new 30amp circuit cause the failure, or just expose a PCS issue that had already been happening? (The straw that broke the camel's back)
5. Should I retake possession of the vehicle and try charging at a supercharger, and if that works, try charging at my home again?
6. The car has been off a charger for 2 weeks now (38% battery currently) and is still in the shop. Can this harm the battery?
7. Should I bite the bullet and pay the $2.4k to get the PCS replaced?
8. If I get the PCS replaced, and the mobile connector is indeed bad, is there any risk of a bad mobile connector harming the PCS?

Most of these questions probably the SC can answer better, especially the part about if they potentially reset something to get things working again. It could also be there was an internal fuse/setting that automatically reset.

From your description, it would appear your mobile connector was faulty, probably you charging on your 30A circuit put it over the edge. When you say your lights dimmed on the 15A circuit, does that happen even before you plug in your car? That should tell you pretty clearly if your mobile connector was faulty. If it were me, I would have brought the mobile connector with the car and let Tesla determine if the mobile connector was faulty also. You can still ask the SC what to do in this regard.

As for your PCS, it's possible the mobile connector damaged it also, but it's also possible that your PCS had half of it die before this happened and you never knew about it given you never charged above 32A. This actually is a very common problem for Model 3s of your era:
Power Conversion System (PCS) failure

Although TSBs generally only apply to cars still under warranty, I would check if these two PCS related ones apply to your car. If they do, you may be able to more easily argue to get it replaced for free (rather than having to fight through arbitration as I link later).
https://static.nhtsa.gov/odi/tsbs/2018/MC-10148850-9999.pdf
https://static.nhtsa.gov/odi/tsbs/2018/MC-10142980-9999.pdf

As for the SC failures, hard to say if you didn't capture what the error messages actually said. Have you ever tried supercharging previously before this whole thing happened? Do you perhaps have a salvage car that has supercharging disabled? Is it possibly an issue with your payment method?

1. And of course, why isn't the PCS considered part of the high voltage battery (for warranty purposes)? I'm at only 18k miles, but past the 4 year basic warranty point.

I guess my question to the forum is, what would you do in this situation, or, is there anything I'm missing or not thinking of?

Thank you.

There are long threads discussing this. This one fighting arbitration laid out most of the points of both sides:
Arbitration decision of my PCS dispute

Basically, from Tesla's perspective, the PCS with the OBC (onboard charger) was always considered separate from the battery pack (it's actually a complete separate component on the Model S/X, but still under the rear seats) and in EV terminology the OBC is generally considered a separate component from the battery. It is also separately serviceable and can be accessed from the top. For ease of manufacturing, Tesla put the PCS in the battery enclosure.

The people arguing against that say that when Tesla does a battery replacement, they replace the PCS also, given it comes with the replacement battery pack as a whole unit. Thus they argue it should be considered part of the battery warranty, especially given Tesla did not explicitly exclude it.

So far people have failed to win in arbitration however.

 

[davewill]

I agree that the PCS failure likely predates all these problems, but was undetected until the SC checked. I suppose there's a slight chance some bizarre surge or other issue took out the PCS module and the mobile connector at the same time, but I doubt it

I'd ask them to charge the car to a decent level (enough to drive around a couple days, try a few things and get it back to the service center), buy a new mobile adapter, and pick it up. Try charging at home with the new mobile adapter, and try supercharging. If both work, then you can probably continue on with only 32a charging available.

If home charging still fails, you might have a wiring problem that needs to be addressed. If supercharging fails, then the service center has failed to properly diagnose the car.

 

[4ntm4n]

When you say your lights dimmed on the 15A circuit, does that happen even before you plug in your car?

The lights only dimmed when the car was plugged in. I just plugged in the mobile connector, without the car, and the lights didn't dim. The mobile connector green light was solid. (The car is still at the shop, so I can't currently test with the car plugged in again).

I would have brought the mobile connector with the car and let Tesla determine if the mobile connector was faulty also.

I'll bring in the mobile connector when I pick up the car, thanks.

given you never charged above 32A

I've charged on superchargers many times, however, prior to my new 30A circuit, I had never charged above 15A when not supercharging. Does supercharger use a separate part of the PCS?

I would check if these two PCS related ones apply to your car. If they do, you may be able to more easily argue to get it replaced for free

Worth a shot, I'll try, thanks.

Have you ever tried supercharging previously before this whole thing happened?

Yes, many times without problem.

Do you perhaps have a salvage car that has supercharging disabled?

Pretty sure I don't have a salvage, I hope not. Bought it brand new from Tesla in May 2018.

Is it possibly an issue with your payment method?

Wow, it's possible. I did recently receive a new credit card with updated expiration date and probably updated security code. I don't remember the supercharger error mentioning a payment issue, but it's possible I overlooked it. Wish I could access logs. I look forward to picking up the car from the shop and testing at a supercharger again.

I'd ask them to charge the car to a decent level

Worth asking, thanks.

buy a new mobile adapter, and pick it up. Try charging at home with the new mobile adapter, and try supercharging.

Just to confirm, when you say mobile adapter, you mean this $230 USD Mobile Connector, right? (just want to confirm connector vs adapter before I buy)

Try charging at home with the new mobile adapter, and try supercharging. If both work, then you can probably continue on with only 32a charging available.

Will do, thanks.


Thank you both, appreciate it.

 

[davewill]

Just to confirm, when you say mobile adapter, you mean this $230 USD Mobile Connector, right? (just want to confirm connector vs adapter before I buy)

Yes, that one. Since you were reporting problems with both the 5-15 adapter and the 30a adapter (14-30?), I'm making an assumption that, assuming the car isn't at fault, your mobile adapter itself might be the problem rather than the individual adapters. If you can get the service center to test your mobile connector and confirm there's nothing wrong with it, then maybe you don't need to try a new one.

You need to be methodical in troubleshooting the problem here. Ideally you would have a second known good set of everything, including cars and electrical outlets, at your disposal and try changing one thing at a time until you find exactly what is wrong. Since that's a tough ask, you'll have to be very logical about what you have and have not tried. If you can try a different outlet somewhere, or have a friend that can come and try to charge at your place, that would be very helpful.

Finally, yes, Supercharging is fundamentally different from regular charging. In regular AC charging, the PCS takes the incoming AC power and converts it to the precise DC voltage needed to charge the battery. That's why Tesla calls the mobile and wall connectors, "connectors" rather than "chargers". The charger itself is inside the car.

The Supercharger, on the other hand is a true charger. It connects directly to the battery and supplies the DC voltage to charge the battery, bypassing the PCS. It's possible to Supercharge with a broken PCS.

 

[4ntm4n]

What a mystery.

I brought the mobile connector to the shop. They tested it and said it was working fine.

They also confirmed that neither a software nor hardware reset was performed. (I asked because I thought it might have explained why they were able to charge at their shop despite it no longer charging at my house.)

I then drove to the same supercharger that didn't work ~2 weeks ago. I intentionally didn't update my credit card / payment method, and it charged fine. Therefore, I'd conclude that a payment issue wasn't the reason for the car failing to charge on two different supercharger stalls ~2 weeks ago.

After the car charged successfully on the supercharger, I drove home. I plugged into the 15A circuit I've been using for 5 years, and the car charged fine. No flickering lights, no errors this time. Next, I plugged into the new 30A circuit, and the car charged fine. No tripped breaker this time.

The SC didn't perform any labor. Nothing has changed (to my knowledge). Yet the car is charging again.

Except now I have a $390 + tax bill. I was assuming I'd pay only a $195 diagnostic fee, which is understandable, but I need to check on why it's $390 (double).