openinverter forum

Hi Everyone, I am doing my first run on my new Tesla LDU drive shaft conversion today and have run into a bit of a snag. It's a bench test run and I'm using a 115 volt rectifier with a couple of 80 volt 6000uf caps in series to give me about 160 volts and 3000uf which gets clean DC out. Before I go totally pulling my hair out like last time I set up my Mustang (it's been a year) I thought I'd asked if this would work or is there just not enough power there to push the motor. If it's not I can stop here and buy some batteries. The issue I am having is that when I push the start button the main contactor just shuts off. I've tried moving the UDCSW and UDCMIN down to 50, then tried 100 just for a reference. Damien had told someone to go down to zero with a 40 to 100 volt setup but I was a bit concerned that it may be too low in my setup. I did check throttle pot trace and I get good travel from 940 to 4000 ish. Double and triple checked wiring 12 volt and 160 volts. If anyone has a thought or 2 that what I'm missing, thank you in advance. I went over almost all the threads about this again and tried a few things but back to square one.

Try looking at the interface, ask it for recent errors, both before and after hitting start. Also look at inputs and outputs in the interface, see if they make sense.
Check contactor wiring - main contactor should be off until you hit start, correct? Because precharge is the one that turns on first.
Check tripmode.
Check UDC readings, see if they actually match what you're seeing.
UDCSW can be set to zero if you're careful, just be sure not to hit start until it's precharged a bit.

I ran a Siemens motor with 2200uf off 240v and it did fine.
If your caps are in series I'm pretty sure you get 6000uf still, though 160 rated is pretty low for use at 160.

Hope some of this helps!

Thank you, I'll go over it again. I ordered a 2700uf 200volt cap to replace the ones I have just to be safe. I'll be gone until next Saturday so I'll get back at it then.

Hey everyone!

I just ordered the LDU drop-in board, and I also got a Performance LDU on its way!

I already searched through the forum, but I just want to ask one more time to make sure:

I'm going to use the LDU in my 1995 VW Golf, which I already built last summer with a 90kW electric motor, but it isn't very fast at the moment.
To mount the motor in the front (I know, it's a lot of power for a FWD), I have to turn the motor around and run it in reverse. I know it's electrically possible, but what about the mechanical aspect? Do the bearings and gearhousing withstand al the power running in the wrong direction? The gears are cut in one direction, which means you are pushing the opposite bearings. I know Mercedes en Toyota have also used the LDU in their cars in the past, with special gears which are cut in the other direction. Those gears would solve the problem, but they are very, very hard to find.

Are there a lot of people who are running their LDU in reverse in high-power applications? Are there any known mechanical failures?

I was thinking about another possible way to solve the problem:

I could roll the LDU upside down, but I would need to change the oil inlet back to the floor of the unit. Has anyone tried this before? This would be my very last resort...

Hi and welcome
See here:
viewtopic.php?f=10&t=1478&p=24796&hilit ... rse#p24796

Roadstercycle wrote: ↑Mon Apr 19, 2021 10:31 pm Thank you, I'll go over it again. I ordered a 2700uf 200volt cap to replace the ones I have just to be safe. I'll be gone until next Saturday so I'll get back at it then.

What are you gonna do about regen?
I had the same idea as yours but then decided to just buy some Hybrid packs to have 96cells in series.
So i ended up with a cheap 400volts pack of 1.6kwh and 400volts.

My reasoning was that if you run the unit from the mains and during regen or what every reason the voltage starts to climb there is nothing that can absorb that. So i think you are playing with fire. To run the motor you need like 60Volts if i'm correct.
Also the tuning will depend heavily on the batterypack it self, so more then a quick IO check cant be done on the bench. Tuning it self doesn't make sense.

Also i realized that it will need to be build into the car either way. If it works or if it doesn't work. Another reason i often use for my self is not to have projects within projects. Your project is to build an EV, not a mains 400DC power supply for a EV motor.

Hope i helped of course no offence or pun intended, in the end we all have or our own approaches...

You can simply disable any regen in the software.

jon volk wrote: ↑Wed Apr 21, 2021 6:18 pm You can simply disable any regen in the software.

Didn't know that, and i started of with trying to get Elon chip going so hadn't a configuration to play with.

Is regen disabled when there is over current error?

Overcurrent results in a complete pwm shutdown.

Thank you everyone for the feedback. I am getting an over current warning but I really don't see any reason for it at 160 volts and 15 amps put to it. It was on single and changed it to A/B. Throttle is not pressed. Everything pre-charges but as soon as I push the on button main relay it connects then disconnects. I have uploaded the parameters for viewing. If anyone has a thought I'd love to hear it. I've checked and double checked wiring and it's not the first time using a Damien board. It's probably a setting that I have wrong. Many times a new set of eyes can see the obvious.

Roadstercycle wrote: ↑Sun Apr 25, 2021 3:45 am Thank you everyone for the feedback. I am getting an over current warning but I really don't see any reason for it at 160 volts and 15 amps put to it. It was on single and changed it to A/B. Throttle is not pressed. Everything pre-charges but as soon as I push the on button main relay it connects then disconnects. I have uploaded the parameters for viewing. If anyone has a thought I'd love to hear it. I've checked and double checked wiring and it's not the first time using a Damien board. It's probably a setting that I have wrong. Many times a new set of eyes can see the obvious.

Does overcurrent occur if you select a direction before pressing start?

The over current still shows up when I pressed forward before hitting the start button. Could this be the infamous IC10 issue that others have talked about? The board is V4B board but over a year old as I bought it and never used it until now.

I finally got it working by upgrading to the latest firmware which I should have done in the beginning although that did not change anything. Running Damien's early parameters made it work. So it's running on the bench at 56 volts.

So I began testing my LDU this weekend. Apart from a firmware issue that I'm discussing over in the firmware section, the precharge was timing out. I measured the voltage on both the battery and inverter side of the contactors. The battery was supplying 340V, but with the precharge closed I was only getting up to about 77V on the inverter side.

Could I have the wrong resistor? I'm using this from TE Connectivity:
https://www.digikey.com/en/products/det ... gKRAF0BfIA

Its rated at 100W, what am I missing/screwing up?

P.S.Mangelsdorf wrote: ↑Mon May 17, 2021 12:18 pm So I began testing my LDU this weekend. Apart from a firmware issue that I'm discussing over in the firmware section, the precharge was timing out. I measured the voltage on both the battery and inverter side of the contactors. The battery was supplying 340V, but with the precharge closed I was only getting up to about 77V on the inverter side.

Could I have the wrong resistor? I'm using this from TE Connectivity:
https://www.digikey.com/en/products/det ... gKRAF0BfIA

Its rated at 100W, what am I missing/screwing up?

You have choose 50ohm resistor, that will result in a fast precharge, in my setup I have 300 ohm 200w takes about 1-1.5 second from 0 to 390v. And I only have the inverter no other hvdc equipment.

Maybe measuring the hvdc with multimeter to be sure?

fredd90 wrote: ↑Mon May 17, 2021 12:33 pm

P.S.Mangelsdorf wrote: ↑Mon May 17, 2021 12:18 pm So I began testing my LDU this weekend. Apart from a firmware issue that I'm discussing over in the firmware section, the precharge was timing out. I measured the voltage on both the battery and inverter side of the contactors. The battery was supplying 340V, but with the precharge closed I was only getting up to about 77V on the inverter side.

Could I have the wrong resistor? I'm using this from TE Connectivity:
https://www.digikey.com/en/products/det ... gKRAF0BfIA

Its rated at 100W, what am I missing/screwing up?

Maybe measuring the hvdc with multimeter to be sure?

Those voltages were found with a multimeter.

Is the resistor still good, i.e. measuring 50 ohms?

johu wrote: ↑Mon May 17, 2021 1:37 pm Is the resistor still good, i.e. measuring 50 ohms?

That's one thing I forgot to measure. Will check tonight. I assume so, I bought it brand new.

If you have a DC/DC on the HV lines it will quite probably consume all the current.

Isaac96 wrote: ↑Mon May 17, 2021 3:16 pm If you have a DC/DC on the HV lines it will quite probably consume all the current.

DC-DC is not yet connected

P.S.Mangelsdorf wrote: ↑Mon May 17, 2021 1:40 pm

johu wrote: ↑Mon May 17, 2021 1:37 pm Is the resistor still good, i.e. measuring 50 ohms?

That's one thing I forgot to measure. Will check tonight. I assume so, I bought it brand new.

Confirmed resistor is still measuring 50ohms, dead on.

Could your precharge relay be dead? 340 on one side, 77 on the other is rather a weird failure mode I suppose. Do you know if it is actually a precharging error? It is possible that the inverter is powering itself up, thus drawing more current than can be provided through the resistor.
Resistor is rated for 1700vdc, that's fine.

Isaac96 wrote: ↑Tue May 18, 2021 2:54 am Could your precharge relay be dead? 340 on one side, 77 on the other is rather a weird failure mode I suppose. Do you know if it is actually a precharging error? It is possible that the inverter is powering itself up, thus drawing more current than can be provided through the resistor.
Resistor is rated for 1700vdc, that's fine.

Not certain yet. Gave a few precharge timeout errors, then I updated firmware to deal with an overtemp error, that was patched a while ago, now I'm dealing with a firmware issue (viewtopic.php?f=7&t=1647) that is preventing me from viewing errors, parameters, etc.

I likely won't have time to investigate further until Friday at the earliest.

EDIT: Problem appears to have resolved itself after fixing firmware and parameter issues

EDIT: The right part for IC7 is as follows: LTC1799CS5#TRMPBF

I think I might have found a Typo in the BOM for Tesla LDU V4b. I noticed that the OP amp part number on IC7 is a different package than on the V4b board.

Link to OP amp + Package info: https://www.arrow.com/en/products/mcp62 ... technology

It says its a 8 pin SOT package where as the board silkscreen and pads show a different package/pin arrangement.