Tesla SDU Bench Testing Rig

[glevpete]

I am looking to assemble a method to test Tesla SDU's on the bench. I am looking at more compact and efficient methods aside from the basic "Brain in a jar" method, keeping a whole model 3's worth of harness and electronics intact. I want a method which does not permanently modify any of the firmware on the inverter MCU, and having corresponded with COTS vendors, their products are out because of this point. I want to be able to programmatically spin the motors, unloaded, through a test regime to confirm onboard inverter function and that there are no mechanical issues in the bearings, gears, and rotating assemblies. I need an interface to allow me to run this test program by commanding the motor to speed, and being able to disable regen to avoid back-feeding a mains fed 400V power supply. We are working with various independent repair shops to set up a used parts stream that's a little more professional than just "Buy an unknown condition drive unit on eBay", and testing this particular component off-car is one of our last challenges. Our team has a background working for Tesla, so it's been an interesting adaption to try to perform a lot of this testing without factory tooling and support.

My understanding from reading through the forum is that the "Tesla Model 3 Drive Unit JTAG Adapter" from the EV BMW webshop may be the most appropriate avenue to creating such a test rig. My background is in custom software, controls and electronics for the architainment industry so I do have the general knowledge and tools to assemble a board like this and flash its MCU, but I don't have - and have been trouble parsing - the specific capabilities of these open source tools. Is this tool only useful for loading fully custom firmware, which is not desirable for our application, or can we set values directly in memory on which the inverter will take action, and if so, are these values documented? Is the interface firmware designed in such a way that we can send transfers to it via USB in real time to control its operation, or do any test regimes need to be added before compilation directly into the firmware?

The other thing I am looking to understand is if there is any prior art on the use of Gen1/2/3 Model S chargers as bench power supplies. Given that we are amassing a stock of older, less saleable units, I wanted to explore using them as a 400V source. However I have had trouble digging up instances of using them as a power supply rather than a charger. Any help would be appreciated, otherwise I other 400V source options.

We understand that this may be a lot of disparate information that requires synthesis into a cohesive set of answers and we are absolutely willing to offer monetary or ev parts-in-kind compensation for consultation leading to a working test rig.

[davefiddes]

The Tesla M3 JTAG interface doesn't sounds suitable for your purposes. Currently the only thing that is possible with the freely available tools from TI is the ability to wipe the firmware of the MCU. Doing anything further with the already installed firmware would require security keys from Tesla and special tooling. The only open source software relating to the M3 that exists at the moment is the beginnings of a complete replacement firmware for the device. Sorry.

[tom91]

[/quote]

use of Gen1/2/3 Model S chargers as bench power supplies

This is not possible, due to its internal firmware checks it requires an HV battery connected.

[glevpete]

This is not possible, due to its internal firmware checks it requires an HV battery connected.
[/quote]

Would having a spare disembodied Model S BMS help? I would guess that the BMS is what requests the current from the charger? Either way, if that's the case, it's likely that it's not worth my time versus a standard 3kw DC power supply.

[glevpete]

This is not possible, due to its internal firmware checks it requires an HV battery connected.
[/quote]

Thanks for the clear and concise reply. I will proceed with tearing up the harness and building a brain in a jar. Much appreciated.

[tom91]

This is not possible, due to its internal firmware checks it requires an HV battery connected.

Would having a spare disembodied Model S BMS help? I would guess that the BMS is what requests the current from the charger? Either way, if that's the case, it's likely that it's not worth my time versus a standard 3kw DC power supply.
[/quote]

No

[leftcoast]

I built a testing bench for running model S and model 3 drive units. Also test gen 2 charge units as well as various other high voltage parts. You can get an I3 battery pack for 1500 bucks. The pack is not that big and it gives me 400 volts under a 30 inch square rolling cart. I have a control panel with controls to run test on various different units. Plus a bunch of adapter cables that plug into My bench.