2nd PCS2 failure

[mongo]

Also the PCS is apparently design to handle both DC and AC high power - which you would normally avoid as they complexity of AC or DC presents their own unique design challenges at PCS power levels.

It's a bidirectional DC-AC converter, no way to avoid it.

AC has an additional challenge in that the current flows in both directions. This can cause tremendous stress on components unless the circuit is design to protect against that.

The reported failures seem to be on the DC side MOSFETs, not the AC back to back pairs. The converter switching frequency is way higher than 60Hz, but likely uses ZVS/ ZCS internally.

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[HaulingAss]

The widespread PCS failures in 2024 and 2025 Cybertrucks are attributed to thermal fatigue in the MOSFETs — and this was not a PCS-isolated problem. The drive inverter recall (NHTSA 24V-832) used similar faulty MOSFET components from the same production era.  So the root issue is that the MOSFET spec chosen for the original PCS wasn’t robust enough for the sustained thermal cycling demands of the CT’s 48V architecture under real-world charging loads.

AI gets a lot wrong. We don't know whether the spec chosen for the MOSFETs was wrong, or if the MOSFETs don't fully meet the spec. It's also possible there was a software issue, or other questionable components, that worked the MOSFETs harder than intended.

MOSFET manufacturing is interesting in that the manufacturer tries to make them all the same, but due to various factors, including impurity distributions in the silicon, no two are alike. Each one will have unique efficiency and the more efficient ones will run cooler. The manufacturer tests them and sorts them into batches before selling them. The ones that generate less heat are priced higher because they are more efficient. Because each batch will contain a range of specs, even those in the same batch will have different failure rates depending upon where they fall in the range of that batch.

It could be that the spec chosen for the MOSFETs was borderline, or that the MOSFET manufacturer was pushing the limit of how they graded them. In any case, due to these natural variations, some will fail and some will last the life of the vehicle.

 

[Flynn]

I don’t disagree, but it often seems like people think others don’t already know this. (To be fair many don’t). I should have qualified my post that my ai had been drinking all day

AI gets a lot right too, and is at least a place to start. It sounds like mosfets manufacturing/grading are a lot like cpu/gpus.

I wonder if munroe or anyone else has or will get their hands on some of these for teardown/analysis. Does it really come down to component temp control? Are failures less common in cold climates?

 

[pae1andonly]

Should we do a group order?

 

[vandytom]

Do we know if the recent PCS model are good now? Why is this happening to only us?

 

[SCTesla]

Why is this happening to only us?

Only us as in CT owners? There was an issue with the part.

Tesla will figure it out.

 

[devdrone6]

Do we know if the recent PCS model are good now? Why is this happening to only us?

Yes they are good for NOW - we will let you know in a couple years for sure.

 

[carsly]

waiting on the iPCS; that must be the good one

 

[UberNoob]

waiting on the iPCS; that must be the good one

Apple is planning to make that one

 

[Edphonse]

And the second leg of my PCS2 just failed. I now have 0 at home charging capabilities.

 

[cadamo001]

Had my PCS replaced around 6 months ago. I'm now getting a weird issue where the trucks just stops charging almost every time I plug into any Level 2 charger. I can start charging again from the app and it usually finishes. SC said it's probably the PCS and scheduled me for replacement when it's available. And gave me free super charging until then. So I'm fine waiting for the updated part.
I have a Beast delivered in June 2024 and around 40k miles.

 

[mongo]

Had my PCS replaced around 6 months ago. I'm now getting a weird issue where the trucks just stops charging almost every time I plug into any Level 2 charger. I can start charging again from the app and it usually finishes. SC said it's probably the PCS and scheduled me for replacement when it's available. And gave me free super charging until then. So I'm fine waiting for the updated part.
I have a Beast delivered in June 2024 and around 40k miles.

There might be informative alerts if you go into service mode .

 

[cadamo001]

There might be informative alerts if you go into service mode .

I've looked in Service mode and so did the SC. They tried replicating the problem and couldn't on their level 2 chargers. I can still L2 charge at home at 48a, I'm getting free SC, and they are going to replace the PCS so I'm ok with it for now. If I couldn't L2 charge I'd be more concerned.
I'm about 2 or 3 more SC visits before I ask them to buy it back and go and buy an AWD so let the issues pile up!

 

[mongo]

I've looked in Service mode and so did the SC. They tried replicating the problem and couldn't on their level 2 chargers. I can still L2 charge at home at 48a, I'm getting free SC, and they are going to replace the PCS so I'm ok with it for now. If I couldn't L2 charge I'd be more concerned.
I'm about 2 or 3 more SC visits before I ask them to buy it back and go and buy an AWD so let the issues pile up!

Weird, any signs it's a house side power issue?

 

[cadamo001]

Weird, any signs it's a house side power issue?

I've had the issue at another L2 charger. I also have a model 3 with no issue and charge other tesla's with no issue. I also have 2 chargers and the Cybertruck is the only one that has any issue on either of the chargers...

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