Tesla Model 3 Rear Drive Unit Hacking

[Jack Bauer]

Almost ready for first real prototype from JLC

[Davidk]

Almost ready for first real prototype from JLC

Dont you miss holes for white plastic stands next to ST1/2/3?
Not sure what is under as i did not desolder my board yet.

[Jack Bauer]

Thanks but turns out Artur designed in a different sensor from mouser that doesnt need those holes so saves having to harvest them from the oem board. Have sent the step file for print.

[Jack Bauer]

She's done:)

[Davidk]

Because I desoldered my board i will post few notes for future adventurers:

1. To remove board you need to desolder all joints marked in green, total of 51 solder joints. I used just solder iron and solder wick.
2. You need to desolder High Voltage interlock loop marked in orange, only top and bottom solder joints are actually connected. Be kind to white plastic, it burns very easily.
3. You need to remove clamp over 30 pin connector, just take long flat screwdriver and move latches inward from plug side
4. Remove 11 T20 bolts (they are all same length). Yellow circles.

Now you can remove board, with connector, temp sensors and current sensors. For me this was easy and i did not had issue, i just wiggled it a bit.

Now you can continue with 30 pin connector in purple colour, this is bit painful part:
1. leads and whole surrounding area is covered by solder mask, i used Dremel with small tip to clean as much as i could.
2. Even when i tried a lot i was not able to wick solder from joins and free connector.
3. I ended with propane torch and connector just slid our, by this i obviously damaged board beyond repair/reuse.
4. To do this without damage to board you will need to use hot air soldering station.

Current sensor. Area around is again covered by solder mask a lot, i used Dremel again to clean area around. Housing is hold by 3 T10 bolts, coloured with blue dots. When trying to desolder sensors they slid out from black plastic housing, not sure if this is suppose to happen or not. I definitely used force to press housing away from board. Now i have plastic housing and two sensors which i desoldered later.

Tools used:
Solder iron, Solder wick, Bit of solder and flux, Torx T20 and T10, Dremel with small tip, propane torch.

Totally i spend 6-8 hours, i did not used solder iron for last 15 years and first two joints took me 30-40 minutes...

[Davidk]

If someone wants to reference internals of 3D6 inverter with other versions.

[Jack Bauer]

Thats great info thanks:) Can someone please add this to the wiki.

Edit : Wiki page is here : https://openinverter.org/wiki/Tesla_Mod ... Drive_Unit

[ScythianNite]

Now you can continue with 30 pin connector in purple colour, this is bit painful part:
1. leads and whole surrounding area is covered by solder mask, i used Dremel with small tip to clean as much as i could.
2. Even when i tried a lot i was not able to wick solder from joins and free connector.
3. I ended with propane torch and connector just slid our, by this i obviously damaged board beyond repair/reuse.
4. To do this without damage to board you will need to use hot air soldering station.

Current sensor. Area around is again covered by solder mask a lot, i used Dremel again to clean area around. Housing is hold by 3 T10 bolts, coloured with blue dots. When trying to desolder sensors they slid out from black plastic housing, not sure if this is suppose to happen or not. I definitely used force to press housing away from board. Now i have plastic housing and two sensors which i desoldered later.

I want to preface by saying this is an outstanding post and I will do my best to add to it based on my abilities. to prevent damage, it is best to use a stripping agent to remove the conformal coating on the affected areas. I suspected the conformal coating (referred to in your post as "solder mask") might be polyurethane based, and so found a stripping agent capable of softening said coating for mechanical removal. I did a small experiment on the main TI chip surface to verify function and will post an updated later during the week with detailed images and timings to help anyone using the chemical method in the future.

additional tools needed aside from those listed in this post:
Mg chemicals 8310/8310A as available in your locality or equivalent mg chemicals 8310A

UV/blacklight (I have party store blacklights at home and they work as shown) as conformal coating is uv reactive

Various stiffness brushes

Nitrile gloves, eyepro and respirator with volatile chemical filtering or some kind of active ventilation (or both for maximum safety)

Xacto blade or sharp flat screwdriver (again, peel not scrape, don't want to damage things)

Fine picks and tweezers to aid in coating removal of challenging areas and around leads. I have attached photos from my experiment

before

after

[Davidk]

Thats great info thanks:) Can someone please add this to the wiki.

I will copy it to Wiki once commented by others, I will also add notes around whole motor, how i disassembled it.

conformal coating

Ahh this is naming i was looking for! I also agree with you that chemicals should be used if some are effective. When asking friends about this i was always get answer "if it is automotive you need to use mechanical means, chemical should not work", because of this i used Dremel to clean it. Also damaging board is not a issue from my point of view as it is useless because of Tesla pairing to the car. In case i would like to put it on the wall i would obviously use less destructive means (especially not propane torch )

[davefiddes]

Interesting experiments with conformal coating. I saw a video about someone repairing a potted hybrid module in an old computer the other week using regular paint stripper (with dimethoxymethane) and wondered if this approach might work on Telsa board but didn't want to experiment as I'd really quite like to keep my board operational...

MG Chemicals 8310A is readily available in the UK from Farnell and RS Components so I might give this a try. I still don't understand how the Tesla standby PSU works and this is obviously not something Damien is interested in.

As an aside if anyone in the UK manages to remove the inverter board to install one of Damien's I'd be interested in getting hold of the board for further reverse engineering and to be a dev. board for my firmware project. Doesn't have to be perfect as long as components can be reattached or bridged out. Not worth shipping from further afield.

[Jack Bauer]

I ordered the 8310A from RS today. Also spent a few hours cleaning up the JLC bom and cpl so they dont generate weird errors. Good thing I did as JLC now have the STM32F103VCT6 as preorder only so I "reserved" 10. In any event, am ready to push the button finally to order 2 real prototypes as soon as confirm the fit of the 3d printed version.

[Jack Bauer]

Real prototypes ordered. Wish me luck:)

[Jack Bauer]

In production at JLC. BOM and footprints all match.

[Jack Bauer]

They have arrived

[Jack Bauer]

So far so good. Boards power up , 5v and 3v3 work and I can talk to the STM32.

Getting interesting:)

[Jack Bauer]

Sadly missed one locating peg for the current sensor block. No big deal. I can just snip it on this one.

[Jack Bauer]

[uhi22]

Recently found a german guy who shows some "reverse engineering light" of the front and rear M3 drive units.
Latest video: and ~2 more. In one video he cuts the copper and aluminium to get out the "SiC FETs" but surprisingly just finds IGBTs.
He explains that the front drive unit uses IGBTs, the rear SiC FETs. He also explains why this makes sense. He also explains why the rear unit has the backup power supply: to get a defined state if the 12V is lost and the PMSM creates voltage. He says, the front unit drives a async machine, which does not create voltage when turned without 12V, so there is no need to bring the gate drivers into a defined state, and so no backup power supply is necessary.
Maybe this was already clear, just want to summarize what I found.

[Jack Bauer]

Thanks. Slightly off topic but I was watching one of his videos a week or so ago and it had this weird ai English dubbing. I ended up turning it off and just listening to the German as I could make out a few words and follow the pictures. I'd hate to think what it would make of my ramblings:)

[davefiddes]

I don't think I'd seen anyone say that the front drive unit used IGBTs before. If anyone harbours a desire to run this with Damien's board it would be useful to get an SPI capture of the gate driver initialisation sequence before removing the Tesla PCB from the rest of the inverter. It doesn't need any more equipment than a cheap ebay USB logic analyser and a handful of hook up wires. I'm assuming that driving IGBTs and driving SiC FETs will require different gate driver behaviour even if the circuitry is otherwise the same?

[Jack Bauer]

I'll see if I can get my hands on a front inverter. I did attempt to contact the German guy. So far no reply.

[uhi22]

Just saw: Beatbuzzer already started a thread: viewtopic.php?p=81871#p81871

[Jack Bauer]

[Beatbuzzer]

Good evening together!

I'm the "german guy" But you guys can call me Ingo as well.

First I wanna say, I'm not a professional. I'm just a hobbyist probing (and sometimes sawing) around and sometimes get to something. Content about that I'm only creating in german language, because there are so many english channels out there and I would like to make content for that part of german community, who isn't well in english.

While messing around with my flooded front drive unit I of course found Damiens videos about the rear inverter and was confirmend in some things, but also learned some more things.
And Damien, thanks for listening to crazy AI voiceover But no worries, your videos have to be listened to in original english. Otherwise that legendary ironic humor could get affected.
Where did you try to contact me? Sorry for probably missing your message.

So, to come to an end in this offtopic post: I have a front and a rear drive inverter over here. The rear drive inverter is still not disassembled, but will be. Actually I have some other projects on the table, because I want my youtube content to be varied. But if somebody has questions about my work, feel free to ask.

Greetings.

[Jack Bauer]

Welcome to the forum.