Tesla Gen 3 charger board assembly as of mid-2024

[RobCote]

I'll double check this evening, but I have the charger setup on a table with a 12V battery for testing purposes. The negative post of the battery is connected to the charger case, as well as to the control board ground terminal. The module boards are not grounded directly, but rather through the openinverter control board, if I remember correctly. Last I checked, they were continuous to the battery negative terminal, but I will verify this again.

In earlier diagnostics, I had the module boards connected together via CANL and CANH, then one twisted pair going from one module board to the control board. To simplify things, I removed one module board from the equation, so I'm currently only using one twisted pair from the control board to one module board CAN connections.

Per a recommendation in this thread, I soldered a R120 across the CAN terminals on the module board. Memory is a little hazy on this one, but I think when there were two module boards in the equation, this brought the bus resistance to within spec. But I measured 42 ohms across the module CAN terminals, so I removed the resistor, thinking that could be part of the issue. No change to performance, but it brought the resistance back to 120 ohms, so there's that.

I'll verify all the above as well as resistance at all CAN locations tonight, and take further measurements between U11 and U1.

[RobCote]

Battery negative is connected to the charger case, ground terminal of CAN-to-USB adapter, and pins 1 (labeled ground) and 11 (labeled CAN ground) of 20-pin connector on control board. Module board ground (terminal #2 from L to R) is connected to CONN 3 pin 1. All these points are positively connected. They look janky for testing but they're electrically solid.

Okay, so I'm questioning my sanity here but I'm like nine...ty? percent sure that I checked the module bus resistance while disconnected from the control board at some point before now. But now when I try, even right at the terminals on U11, it's open loop. If I connect the control board, I see 120.0 ohms.

Does that mean the CAN transceiver chip is broken?

[RobCote]

I'm not sure if I'd be wasting time and effort - and risking screwing up - to replace the CAN transceiver chips? Is it likely that they're both faulty but something else isn't wrong?

[tom91]

I'm not sure if I'd be wasting time and effort

Somethings is really broken with the charger so who knows if you will ever fix it or find the fault.

[RobCote]

Well that's disappointing. Guess I should just give up.

[RobCote]

Does anyone know where the can termination resistor is on the charger modules?

[RobCote]

Does anyone know where the can termination resistor is on the charger modules?

[tom91]

Does anyone know where the can termination resistor is on the charger modules?

NOTE: DO NOT SPAM wait for people to answer.

Is there one then? do you measure a resistance between CAN H and CAN L on the board? with no wiring connected?

[RobCote]

I have no idea how that posted again. I apologize.

With nothing connected, it's open loop. I don't know what I'm doing wrong, but even after scraping the clear coat off a couple resistors on the module board I measured open loop directly across the resistor so either I'm an idiot or this thing was subject to EMP. Likely the former but who knows.

[tom91]

... so there is no termination resistor on the charger module board. Hence why you had to solder on an external one.

[RobCote]

Is that normal for there to just not be one at all? How did it operate prior to modification? You recommended to add one, which I did, but I didn't get the impression it was absolutely critical.

I recently removed it during the course of fiddling with things, but I'll put it back if it's in fact necessary.

[tom91]

You are talking in circles. Something is broken and you would need someone with CAN and Electronics knowledge to deep digging into the circuit.

Unless someone has had exactly the same issue it could be anything.

[RobCote]

Winner winner chicken dinner.

Apparently there is something fundamentally wrong with that charger. I finally broke down and bought another off eBay and I wired up one module and it appears we are communicating:



More to come but I have to stop for the moment.

Thanks again to everyone who chipped in. I never thought I'd get this far, and I wouldn't have without your help.

[tom91]

Apparently there is something fundamentally wrong with that charger.

Geeze you dont say. Guess you have to write it off as learning exercise.

Do not go breaking this one by ripping it to bits or just slamming HV into it.

[RobCote]

I confirmed charging with 1 module active this morning. I'll connect the rest of the modules and neaten everything up and put this one to bed.

I learned a ton through this exercise, so it was not pointless even though it could have been avoided. Thanks for being patient as I stumble through. I only wish I had a clear resolution for whomever in the future reading this has this issue.

As a small bonus I upgraded from a 48A charger to a 72A one.