Tesla SDU Knocking\Clunking Noise

[alexbeatle]

Hello fellow ev diy-ers,

I'm bench testing my Tesla SDU with V6 board. Bus voltage about 95V - forklift battery charger.
When I'm in reverse and the motor is decelerating, you can hear a clear knocking\clunking noise. None of that in forward. Wouldn't want to put it into the car before ensuring it's functioning properly.

Could anybody please advise?

Thanks.

[celeron55]

Does it sound exactly the same as if you turned one side of the diff by hand in alternating directions when the motor is not spinning? Can it be uneven friction in the output sealing surfaces doing the same thing?

[alexbeatle]

Does it sound exactly the same as if you turned one side of the diff by hand in alternating directions when the motor is not spinning? Can it be uneven friction in the output sealing surfaces doing the same thing?

Could you please elaborate? I know electronics, but a noob with mechanics....
I only took the inverter side apart to swap the board. Didn't take the gear side apart.

[tom91]

you have driveshaft stumps to put in it? Without them in the spider gears are loose and possibly/likely what is clunking.

Put the driveshaft stumps in to check when rotating by hand with the motor off any strange noises or resistance to rotation is noticed.

[New Electric Ireland]

Could anybody please advise?

It's not clear from the video whether you are running any cooling but if not be extremely careful... you won't be the first person to blow up a SDU inverter

[alexbeatle]

you have driveshaft stumps to put in it? Without them in the spider gears are loose and possibly/likely what is clunking.

Put the driveshaft stumps in to check when rotating by hand with the motor off any strange noises or resistance to rotation is noticed.

Good point. Will try tonight and post back.

Could anybody please advise?

It's not clear from the video whether you are running any cooling but if not be extremely careful... you won't be the first person to blow up a SDU inverter

I'm only running it in short intervals at mid-speed rpm. Should be ok. Thanks.

[alexbeatle]

This is the first time I'm working with these.
So I've got these blanks meant for the SDU. See attached. Is this how far they're meant to go? I cannot put them any farther, but to me it looks like they should. There's a ring on them which is what seems to prevent them from going in farther.

[tom91]

Take the clip off, it will lock it in place no need for that right now.

[alexbeatle]

Actually the noise went away after inserting the stumps!
I'll mark it solved. At least for now.
Thanks a lot to everyone!

[New Electric Ireland]

I'm only running it in short intervals at mid-speed rpm. Should be ok. Thanks.

Just to be clear we've seen SDU inverter failures with very light testing because the heatsink has so little thermal mass. iirc Damien, Zero EV, and EV Romania also became aware of this issue during the early days of SDU testing. Obviously it's your call but you don't get any second chances with the Tesla inverters.

[celeron55]

I'd imagine just filling it with coolant without circulation, just plugging the pipes once it's full, would increase the thermal mass sufficiently to avoid any damage when testing.

[alexbeatle]

I'm only running it in short intervals at mid-speed rpm. Should be ok. Thanks.

Just to be clear we've seen SDU inverter failures with very light testing because the heatsink has so little thermal mass. iirc Damien, Zero EV, and EV Romania also became aware of this issue during the early days of SDU testing. Obviously it's your call but you don't get any second chances with the Tesla inverters.

I'd imagine just filling it with coolant without circulation, just plugging the pipes once it's full, would increase the thermal mass sufficiently to avoid any damage when testing.

Decided not to take chances and proceed with installing into the vehicle. I think it's in the good state. Will mount the motor, add axles, refill the gearbox fluid, add cooling line and then proceed with the rest of the testing.