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VX220 with Tesla SDU

35905 Views 188 Replies 19 Participants Last post by  catphish, 
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Hi All,

I just wanted to create a thread for my upcoming project. I hope to modify a VX220 (Opel Speedster) using a Tesla SDU, with a focus on light weight, fun, and open source where possible.

The parts I currently intend to use:
  • Vauxhall VX220 2.2L NA
  • Tesla SDU
  • Openinverter Tesla SDU controller
  • LG Chem 16S packs (96s2p total)
  • 6.6kW 400V+ charger with CAN (brand undecided)
  • DIY central controller to link together inverter, charger, BMS slaves, EVSE, and OEM Vauxhall gauges
  • Appropriate replacements to power the cabin heating system and brake assist / ABS.

I have obtained the car, and fingers crossed, the Tesla SDU will fit. I will be getting professional assistance with the mechanical fitment, as my expertise is with electronics rather than mechanics, but hopefully I will be learning the latter as I go along.

I hope to program my own controller to link everything together, using CAN where possible. My main question for now is about how I will integrate the battery modules (whether I can use the LG OEM BMS slave modules, or whether I'll have to replace them). I hope to update this thread as I progress in the coming weeks (months?!).

Any advice on the general setup would be welcome, and any information about the LG Chem BMS slave protocol would be greatly appreciated.

Vauxhall VX220
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2
Had a god day on the car today. Did the final installation of the charger, coolant pump, header tank, and vacuum pump. Ran all the coolant lines, tested the pump and ran water through to test for leaks. All seems to be working well! I went with a simple loop: Radiator -> Pump -> Inverter -> Charger -> Motor -> Radiator. I also re-installed the brake master cylinder. Sadly sticking with the OEM vacuum brake boost for now.

Coolant header tank


EV charger mounted in car
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I doubt it's the shrink fit, but the welds that may crack...hundreds vs thousands of degrees.

Which is why you heat it cherry and slow cool it (jab it into a sand bucket is a poor man's slow cooling annealing method)
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5
Today was a big day of low voltage wiring! I've made up and installed low voltage looms for each component and brought them all to a single location:
  • VCU (charge controller)
  • Gear Selector
  • Small Drive Unit
  • Charger / DC-DC Converter
  • The existing OEM engine loom (power, throttle, warning lights, etc)
  • Vacuum pump
With all that in one place, I am now ready to splice everything together as needed. The Dutch 12 pin plug for the battery box really is a joy to assemble. Highly recommended!

I made some last minute changes to my wiring plans to ensure that the CAN bus meets the standards. In particular, making sure that stubs are kept below 300mm. Because my battery box contains a "dead end" on the CAN bus, and because the SDU contains a termination resistor, I decided to start the bus in the battery box, run it all the way to the front of the car to the VCU under the dash, then all the way back to the rear, to the charger (there are 2 CAN pairs in the charger loom) and then finally into the SDU.

I also took the opportunity to give the car 12V for the first time in a while. I have an array of warning lights for the brakes, ABS, and airbags, but hopefully those will be happy once the brakes and seatbelts are reconnected. I've bought an OpCom OBD2 cable to reset those fault codes as needed. Apart from that, everything still seems to work as it should, and power is available where I need it to be. I've tested the vacuum pump, which is a little loud as expected, but only runs during braking to replenish the vacuum, so not too annoying.

Electrical wiring Art Creative arts Electrical supply Wire
Circuit component Font Line Audio equipment Electrical wiring
Car Vehicle Land vehicle Gear shift Speedometer
Electrical wiring Gas Automotive exterior Cable Composite material
Automotive tire Hood Vehicle Motor vehicle Tire
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Done most of the splicing. it looks a little messy, but once I've shortened a couple of wires and wrapped it up, it should be nice and neat. So far so good. Everything appears to work so far including the OWM throttle.
Heatshrink on automotive wiring
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So today I've been reflecting in potential problems with my design. There are two things of mild concern:
1) The main contactor has an inrush current of 2.5A. The Openinverter SDU board is driving the contactors using NCV8402. These should be able to supply about 3A but it's something I need to be careful of.
2) My battery box has a space on each side of the batteries where contactors etc are mounted. The batteries are clamped down from the top, but I suspect it would be a good idea to place some hard plastic spacers between the side of the bateries and the side of the box to ensure that the battery terminals are not taking any of the (sideways) weight of the batteries during cornering.

I've also realized with some embarrassment that I have no idea how to fill the SDU with oil!

On an entirely different note, I realised today with some irritation that there are two different standards for CAN on a DE-9 connector. CAN has one standard but OBD2 has its own. This means that I can't plug an OBD2 cable directly into a CAN debugging tool. I'll have to find (or make up) the correct cable.
Rectangle Font Line Parallel Number
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Joske
catphish said:
The SDU is now fully installed so next time I'm with the car, I will measure the height from the floor for you (when loaded with the SDU but not the batteries). I will measure both the bottom of the sump and the centre of the driveshaft entry holes to the ground.

I really didn't give much thought to the position of the SDU when I started the project. I was so glad it fitted so well into the original rear engine mount that I didn't really stop to consider if it was actually in the right place or not! I now realise that the differential is a little forward of the rear wheels. I roughly measured the angle of the shorter driveshaft at around 9 degrees. The CV should be able to handle this, but definitely something to consider.
Click to expand...
Hello Brian, thanks for the update. Purpose of my question is that I would like to investigate if with a modified rear beam we can keep the original driving direction of the drive unit. If we know the amount of modification of this beam we could discuss with a certified engineer if this is allowed to be modified in a way it would allow to have the gearbox in the tesla orientation. Pitty you live the opposite of the world otherwise would like to pass by and check your nice work. thanks.
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catphish said:
On an entirely different note, I realised today with some irritation that there are two different standards for CAN on a DB-9 connector
Click to expand...
Isn't that a nuisance?!? What a hack! What were they thinking?!?

It's tempting to use a pair of screw terminals, but that is not recommended. I've seen control systems in heavy equipment that use a phoenix contact plug with built-in screw terminals. These are not as pretty as a DB-9, but they handle rough service. I may install a DB-9 port with the standard CiA 303 pinout (2&7) with clear labeling. I might include a second well-labelled port with the alternative goofy-foot wiring (5&3), just to simplify direct connection to popular cheap CAN/USB adapters. (The next owner will need remember to terminate only one of them!)
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Joske said:
Hello Brian, thanks for the update. Purpose of my question is that I would like to investigate if with a modified rear beam we can keep the original driving direction of the drive unit. If we know the amount of modification of this beam we could discuss with a certified engineer if this is allowed to be modified in a way it would allow to have the gearbox in the tesla orientation. Pitty you live the opposite of the world otherwise would like to pass by and check your nice work. thanks.
Click to expand...
I do apologise, I still haven't done this, I remembered a coupld of times but couldn't put my hands on a tape measure. The batteries are now in the car, so I will try to get this measurement for you when I can.
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3
Today I completed the low voltage wiring, and got the battery box lifted into the car. I've tested the contactors and made a good start on the HV wiring. Just the inverter wiring to do, and then I can think about powering it all up!

I also filled the oil. This drive unit is designed to take 2.25 litres of Mobil SHC 629. I'm using an equivalent called "Indisyn Mild 150".

I've written some basic code for the charge controller (which I've started calling the VCU because it it also controlling the heater contactor and pumps). Finished / updated wiring diagram also attached.
VX220 rear incomplete

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Small update with good news. I connected up my HV today and everything works so far:
  • Small drive unit controls contactors correctly and spins!
  • DC-DC converter works
  • Heater works
  • VCU is correctly sending the start signal to the inverter (CAN) and correctly controlling the coolant pump, heater, and DC/DC converter.
The only big thing remaining to test is the charger. Hopefully next week I'll get the charge port wired up to test that.

To celebrate I removed some workshop dust and took some photos. This is with the battery box installed without its lid :)

Electric VX220 rear with batteries visible
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I have been quite alarmed by reports of random failures of SDU inverters. I've been working on an openinverter configuration, but I now think I will tune it a little more in line with a configuration from a car that I know has been running without issue for a year. boxster986ev/params.json at master · Zero-ev-conversion-ltd/boxster986ev
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^^ S3XY
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I've run into a fairly serious problem with my BMS. The charger creates high frequency electrical noise on the high voltage system which is interfering with the BMS communications. This means the BMS does not work during charging, not ideal! I am looking into options to mitigate this electrical noise. Hoping to avoid yet another redesign of the BMS!
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<hack>If hardware redesign is not an option, can you do something in software? Suppose you let the charger do it's noisy deed for 60~120 seconds, then stop sending target voltage&current and wait 5~7 seconds for it to stop charging. When that happens your BMS can check the status of the cells and compute a new target voltage and current. Lather, rinse, repeat. </hack>
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Ken S said:
<hack>If hardware redesign is not an option, can you do something in software? Suppose you let the charger do it's noisy deed for 60~120 seconds, then stop sending target voltage&current and wait 5~7 seconds for it to stop charging. When that happens your BMS can check the status of the cells and compute a new target voltage and current. Lather, rinse, repeat. </hack>
Click to expand...
You're right, this will certainly work, if my attempts to fix the hardware fail, I will absolutely do this :)
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Ferrite bead/balun on the charger leads might mitigate the conducted EMI.
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I had another small electrical noise problem, my design for reading the CP line wasn't particularly noise immune, and it received garbage in the rather specific case where both the charger and ignition (ie HV precharge) were on. Luckily this was easily fixed with a capacitor on the CP input.
Capacitor added to PCB for noise filtering
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The front of the car is just about finished now. I got the brake lines reconnected and the new cabin blower hose installed. This means I can probably get on now and re-install the headlights and front clamshell!
VX220 front compartment with new blower hose
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catphish said:
I've run into a fairly serious problem with my BMS. The charger creates high frequency electrical noise on the high voltage system which is interfering with the BMS communications. This means the BMS does not work during charging, not ideal! I am looking into options to mitigate this electrical noise. Hoping to avoid yet another redesign of the BMS!
Click to expand...
I believe I now have a solution to this problem. I temporarily installed an isolating transformer between one battery string and the BMS. That battery string was able to maintain communication while charging at 10A (the most I can easily test). It's a shame I didn't build these transformers into the BMS PCB, but I'm not inclined to remake the board at this point, so I will simply put transformers in line with my data cables, at least for now.

Ethernet transformer on breakout board


As the front end of the car is now (I hope) complete, I've bolted the front clamshell back on! Just waiting on driveshafts now.

Not really related to the conversion, but I've some parts for general maintenance, new brake discs and pads for the rear that I disassembled, new toe links, I caused some damage to the old ones removing them to free the driveshafts, and a new bonnet catch release mechanism the original one really sucks.
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There's a pretty massive shortage of isolation actives right now, with nothing available until 2023 🤬, so it's great you found a workaround.
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