Questions about “fast charge contactor” and “high voltage controller” replacement service to fix supercharging issues

[J-a-x]

I have a 2023 Model Y with 15k miles on it (10 months old). Last week when charging at a supercharger on a road trip I got a “Charging stopped“ message and could barely get home. I noticed that AC charging still worked so I was able to get into a service center in a few days. Even before my service appointment, Tesla sent me a repair quote with the following action:

1. Correction: Contactor - Fast Charge - HV Battery (Remove & Replace)
2. Correction: Controller - High Voltage (Non-Structural Pack) (Remove & Replace) - Remove
   
   and Replace​

It seemed a bit odd to diagnose it without even seeing it but seems like they could via remote diagnostics? Anyway whenI brought it into the service center they said it would be a quick one-day repair, no need for a loaner etc. I was happy with this, except at the end of day-1 nobody ever checked in with me about the status and nobody answers the message feature in the app while in service mode so clearly it was not a 1-day job. On day-2 I was able to get in touch with my service advisor who said they spent all of the first day diagnosing the issue (despite sending me a diagnosis prior to me bringing it in) and that it would take another day, which turned into another 5 days...

I am still without a car and its really hard to get in touch with anyone (they don’t answer in-app messages and only answer the phone maybe once every 10 times i call, and never return phone messages). I’m not even sure if service is working on it over the weekend or not.

I am curious if the actions above (replacing the contactor and controller for high voltage DC fast charging) are major repairs which one would expect to take a significant amount of time (contrary to what the advisor originally told me), or if it’s a relatively simple procedure. For example do they need to remove the actual battery pack to do this work, or is the car designed in such a way that replacing contactors and controllers is relatively trivial (swapping out some circuit boards etc)?

Has anybody ever had this type of work done? If so, how long did it take for you? I’m also interested (mostly out of purely personal interest) what this type of job typically involves? I understand the procedure for most ICE engine repairs, but EVs are newer to me so just curious what is involved here.

I’m also curious what may have caused this (manufacturing defect?) and how likely the replacement part is to last as this could be a major source of maintenance cost if out of warranty. They say EVs require less maintenance cost than ICE engines, but that’s not the case if I need to replace these parts every 15k miles.

 

[GHammer]

The DC charge contactor is subject to a lot of stress given the amount of power it switches. Consequently failures of this part is not uncommon on all Teslas of all years but it's not something that happens to a large percentage of cars or is likely to reoccur. It's never failed on any of my 3 teslas, each over 100k miles.

Edit: I'll add I've heard of this failure enough times that when you first posted the symptoms in your other post I knew what the failure was.

 

[J-a-x]

It’s nice to hear this never happened to you over your 3 cars.

It seems to me that either the issue was caused my wear and tear due to high currents (in which case I should expect it to happen again) or it was a one-off manufacturing defect and once its fixed it should be fixed for the life of the car. Your experience gives me some hope it may be the latter, although I do have a friend who had a similar charging system issue with his model S so it’s definitely somewhat common. Luckily has happened in his garage (and with the LV not HV system) not while on a roadtrip.

It seems that while EVs are much simpler than ICE cars in a lot of ways, the fueling system is quite complex and under a lot of stress and it seems to me that this might be the source of the highest maintenance costs over the life of my car…

 

[J-a-x]

So Tesla originally said it was a one-day repair, which turned into 2 days, then they said they needed to keep it over the weekend, today they say they need to keep it until Wednesday. I'm pretty sure they didn't do any actual work on it until today because today the car finally changed its GPS location to inside the repair shop for the first time (over the weekend it sat in the parking lot possibly with the doors unlocked according to TeslaFi which I'm not too happy about)...

Also today after my car moved inside, it seemed to power itself down (the app no longer reports the cars battery status etc). So maybe they're working on the electrical system finally.

Still not exactly sure what this type of repair work involves as in how hard is it to remove and replace the HV contractor and other charging related hardware but it's definitely not a quick repair.

 

[MP3Mike]

If you want to know what is involved start a, free, subscription to the service manuals on the Tesla site and take a look: Tesla Service

It looks like 3.36 hours of work. (Assuming no overlap between the two procedures.) (Just pulling and reinstalling the pack is ~4 hours of work, so it would seem the pack doesn't have to come out for what your Model Y needs.)

 

[J-a-x]

Definitely << 5 days. Hmm... wonder if part of the delay was them ordering parts. Wish they would have let me keep my car until they were ready to go if that was the case.

EDIT Btw thanks for that service link. Very helpful!

 

[Eric33432]

It seems that while EVs are much simpler than ICE cars in a lot of ways, the fueling system is quite complex and under a lot of stress and it seems to me that this might be the source of the highest maintenance costs over the life of my car…

When I look at this video of a modern Tessie HV battery, I am not so sure EVs are simpler than ICE cars. They may be simpler mechanically, but it looks like the components in the battery could be more complicated than the mechanical components in an ICE car?

Even though this is from a Model S Plaid, he says this pack is similar to the MY and M3 packs, in fact, the design of the MSP and MY packs came from the M3.

As I understand from this video, and if I am mistaken please correct me, the following is true:

The four contactors, and the BMS, are located in the battery pack. So the pack must be removed, opened up, the items serviced/replaced, closed back up, and reinstalled in the car to service or replace the BMS and/or contactors.

Also, there are two sets of contactors (two for each set, total of four) located within the battery pack. One set ("charging contactors") switches the charge port either directly to the battery for DC Supercharging, or to the input of the battery charger (rectifiers) for AC charging. The other set ("HV on/off contactors") switches the output of the HV battery on and off to feed the motor(s) and the heat pump.

The 15 volt DC to DC converter is also shown in this video to be located in the battery pack. This is analogous to the alternator in an ICE car, and is what provides the power for all the low voltage components in the car. I am not sure if this operates independently of the HV on/off contactors; i.e. can this operate to provide LV power to the car when the HV on/off contactor is turned off, or do the HV on/off contactors need to be on for the DC/DC converter to be working, and exactly what is the situation when the car is "sleeping"?

Seems like a lot of work to have to service any of these components. So, J-a-x, if this is true, looks like a pretty big job to deal with all this, if this video, and my understanding of it is what is being done to your car. I would also be curious if the 50,000 mile 4 year warranty applies to all of these components, even though they are located within the battery. I suspect that is the case, and the 8 year warranty only applies to the actual battery cells. Anyone know for sure?

 

[MP3Mike]

The four contactors, and the BMS, are located in the battery pack. So the pack must be removed, opened up, the items serviced/replaced, closed back up, and reinstalled in the car to service or replace the BMS and/or contactors.

Nope, most of that stuff can be accessed with the pack still in the car. It is in the "penthouse" which is accessible by removing the rear seat cushion.

 

[Eric33432]

Nope, most of that stuff can be accessed with the pack still in the car. It is in the "penthouse" which is accessible by removing the rear seat cushion.

That is good to know. True for all current production Tessies?

The video shows the positive HV on/off contactor located at the rear end of the battery assembly. Do you know if that contactor is replaceable with the pack still in the car?

What about my warranty question?

 

[J-a-x]

I got my car back today. They only replaced the contactor, not the controller in the end. From what I understand after looking at the service manual, the contactor can be replaced by accessing the battery penthouse which requires removal of a rear seat. So looks like the battery doesn’t need to be removed only the seat to access the battery penthouse.

 

[Eric33432]

I got my car back today. They only replaced the contactor, not the controller in the end. From what I understand after looking at the service manual, the contactor can be replaced by accessing the battery penthouse which requires removal of a rear seat. So looks like the battery doesn’t need to be removed only the seat to access the battery penthouse.

Glad you finally got her back!

Do you know which contactor(s) was/were replaced? Probably the ones that control the routing of the AC to the rectifier (charger) or the DC directly to the battery?

 

[J-a-x]

Glad you finally got her back!

Do you know which contactor(s) was/were replaced? Probably the ones that control the routing of the AC to the rectifier (charger) or the DC directly to the battery?

I assume DC since it only affected DC fast charging.

Technician notes in the app said:

Diagnosed and Replaced Fast Charge HV Battery Power Switch.

And the invoice said:
ASSEMBLY - FAST CHARGE CONTACTOR - HIGH VOLTAGE BATTERY(1095145-01-J)

 

[MP3Mike]

Probably the ones that control the routing of the AC to the rectifier (charger) or the DC directly to the battery?

It doesn't reroute it, it just connects the battery directly to the charge port. (Which is still connected to the AC charger.)

 

[Eric33432]

It doesn't reroute it, it just connects the battery directly to the charge port. (Which is still connected to the AC charger.)

So the Tesla described "FAST CHARGE CONTACTOR" is operated (coil energized) when DC is coming in through the charge port, which is connected directly to the battery and left still connected to the rectifier/charger input terminals, which just ignores the DC voltage?

Is this common to all the S, 3, X, and Y vehicles?

Then the problem J-a-x and others on this thread is pretty much the contactors not operating due to either defective contactors, or defective circuitry which sends the voltage to operate the contactors?

 

[MP3Mike]

So the Tesla described "FAST CHARGE CONTACTOR" is operated (coil energized) when DC is coming in through the charge port, which is connected directly to the battery and left still connected to the rectifier/charger input terminals, which just ignores the DC voltage?

Yep.

Is this common to all the S, 3, X, and Y vehicles?

Yes.

Then the problem J-a-x and others on this thread is pretty much the contactors not operating due to either defective contactors, or defective circuitry which sends the voltage to operate the contactors?

Most likely.

 

[J-a-x]

The solution was replacing the contactor itself, not any hardware connecting to the contactor. Therefore, I think the contactor itself was defective.

The Tesla service representative that I talk to when I picked up my car told me that the contactor they put in is better/newer than the contactor that was installed in the factory and burned out. I have no way to confirm that and actually I kind of doubt it. I bet it’s the exact same part unless something changed in the last 10 months and there’s a newer version of the contactor.

 

[BURNS G]

The solution was replacing the contactor itself, not any hardware connecting to the contactor. Therefore, I think the contactor itself was defective.

The Tesla service representative that I talk to when I picked up my car told me that the contactor they put in is better/newer than the contactor that was installed in the factory and burned out. I have no way to confirm that and actually I kind of doubt it. I bet it’s the exact same part unless something changed in the last 10 months and there’s a newer version of the contactor.

2023 MYLR with 223 miles on it (1 month old). 2 days ago, I had the OTA software update. After the completion of the update I received a notification software update complete and after a few seconds, I received another notification battery low need to charge" but my battery is 76% at that time and not connected to a charger. I thought it was a glitch due to the update. After that notification pop up, I cannot see it in my App. I called the following day and they said that a technician can remotely diagnose the notification. The car runs fine and I do not see any pop up on the screen. The technician diagnosed it by asking me a question on the app via text about what is my concern. After I sent them the information they immediately replied with a diagnosis. The diagnose is I have to bring the car to service center. Here is the quote : Diagnose and replaced high voltage controller
Correction: Controller-High Voltage (non-structural pack) (remove& replace) $351.90
Correction Diagnosis: High Voltage Circuit Integrity check $255.00
Labor hours 2.38
Total Amount $606.90
Pay Type: Customer Pay
Cost estimate $606.90 You will not be charged at this time. Repairs covered under warranty will be waived.

I am skeptical on the diagnosis as they have not seen the car or check the log in my car. I heard a lot of horror stories bring the car to service center and instead of being fixed, more problem will arise.

 

[MP3Mike]

I am skeptical on the diagnosis as they have not seen the car or check the log in my car.

How do you know that they haven't check the logs in your car?

 

[BURNS G]

How do you know that they haven't check the logs in your car?

The technician told me they can only see the log when they pull it from the car system.

 

[MP3Mike]

The technician told me they can only see the log when they pull it from the car system.

Which they can do remotely...