openinverter forum

Hi!

I have just started converting my VW Transporter from 85 to electric. It has the original petrol engine (1.9 liters 57kW) which works fine but I have been thinking a while about converting a car to electric drive and this car is perfect to do so. It doesn't weigh too much but has a lot of space and can carry a lot of extra weight.

I got hold of a used Tesla model S SDU for only 9500 SEK (950€) which I think is really cheap for such a powerful and complete motor. I also found a used Model 3 battery pack, 55kW, for 50000 SEK which also isn't too bad. They both have only been used between 10000-18000 km. I bought them both from Grønvolds bildemontering in Norway.

I got the things yesterday and we (me and my brother) started disessemble the battery pack and found 4 modules at 88.8 Volts. They are only 130 x 35 cm and about 50-60 kg which makes them very compact. They are also going to fit perfectly under the car.

I also installed the openinverter board for the SDU but I have to get some HV connectors because those wasn't included with the motor.

My plan is to use an Orion BMS 2 for the battery and charge them with an Elcon TC charger 6.6kW. I also hope that I can reuse the contactors that was included in the battery package, picture below.

Hopefully I will get the HV connectors and cables before next weekend so I can test the motor and controller.

/Johannes

Woops was supposed to post this in the projects category. Can a mod move it?

Moved.
Awesome project, very handy that you can fit complete M3 modules.
When charging for the first time watch your cell voltages.

Oh, the 55kWh modules are all that small.

Great bargains you got! Good job. And very nice project!

Awesome project! My goal is very similar except I’d like to find a T3 Doka here in the States and use a full Model 3 75kwh pack. Do you think the full length modules will still fit underneath?

Working myself on a similar project with my T3. According to my measurements the full 75 modules will not fit. Distance between rear crossbeam and front beam with suspension mounts is just mms to small.

But the 55 modules look great. I didnt consider these until now.

Good luck with your project

tmotion wrote: ↑Tue Oct 13, 2020 6:23 am Working myself on a similar project with my T3. According to my measurements the full 75 modules will not fit. Distance between rear crossbeam and front beam with suspension mounts is just mms to small.

But the 55 modules look great. I didnt consider these until now.

Good luck with your project

Yep, I had the same concern because I couldn't find the measurements of the smaller modules so it was a great suprise when I opened the pack. But I guess you could possibly fit them inside the car depending on how much space you need.
Thanks and good luck to you too!

ChrisFullPower wrote: ↑Tue Oct 13, 2020 1:37 am Awesome project! My goal is very similar except I’d like to find a T3 Doka here in the States and use a full Model 3 75kwh pack. Do you think the full length modules will still fit underneath?

Like I wrote above the large modules are a bit too large for fitting under the car. But from what I know 2 modules are smaller (~170cm) which you possibly could fit under the car but the 2 long ones (~190cm) are too long.
If you want more capacity I guess you could buy 6 modules of the 55kW/h pack and fit the other two inside the car.

Does anyone know what type of oil and how much you need for the SDU differential? Couldn't find any info but remember that I read a thread about it some time ago.

I hope this helps you further...

Thanks a lot!

Does anyone know a good way to charge the HV battery with a solar panel? Because I'm planning to have at least one 300W panel on the roof but most of them are 12vDC. I could just charge the 12v battery and maybe skip the DC to DC converter but it would be nice if there was a way to charge the big battery. Maybe there is some bidirectional DCDC converter? Or am I just hoping for too much?

Not very elegant or efficient, but could you use a 12V to AC inverter and plug it into your AC charger? It would take a long long time to charge.

DaveH wrote: ↑Wed Oct 21, 2020 6:22 pm Not very elegant or efficient, but could you use a 12V to AC inverter and plug it into your AC charger? It would take a long long time to charge.

Yes I have been thinking about that but would loose a lot of efficiency. Maybe 80% efficiency. The reason I ask is that I'm going to use the car as a campervan and it would be great to get some extra juice if I'm far away from the grid.

I have been thinking about this as well for my T3 but in the end concluded that it is not worth it. On my poptop i can put a nice big 445Wp panel of 2.1*1 meter. But still this will give me 350wh of charge in perfect conditions. Which with a T3 campervan equals 1 kilometer of range. (70kwh pack is 200km)

So a full day of charging will give you maybe 8km of range....

So in the end I settled for solar charging a big 12V 200ah battery for all my appliances and stuff like heated windscreen, seat heating, fridge etc.... i even plan to have a VW 800watt 12v ptc heater element fitted in the original air distribution box. This way my dc-dc will be used less often. The mppt inverter will send a signal when charge is below a certain value, turning on the dc-dc. I think this way you have minimal losses and it covers the purpose: using the sun to power your campervan holiday.

Safety bonus is that my high voltage pack doesnt need to be “live” all the time when camping

tmotion wrote: ↑Thu Oct 22, 2020 7:14 pm ....
Safety bonus is that my high voltage pack doesnt need to be “live” all the time when camping

This is actually the best reason not to have solar charge the HV pack!!! Solar panel is money better spent into better charging system / fast charging.

So in the end I settled for solar charging a big 12V 200ah battery for all my appliances and stuff like heated windscreen, seat heating, fridge etc.... i even plan to have a VW 800watt 12v ptc heater element fitted in the original air distribution box. This way my dc-dc will be used less often. The mppt inverter will send a signal when charge is below a certain value, turning on the dc-dc. I think this way you have minimal losses and it covers the purpose: using the sun to power your campervan holiday.

Safety bonus is that my high voltage pack doesnt need to be “live” all the time when camping

That's what I was thinking of as well. It will eliminate most the power needed for all the extras from the HV battery. And be a lot easier/cheaper. I currently have 2*12v 60ah batteries but might get a big one instead.
Thanks/
Johannes

Johannes.l wrote: ↑Wed Oct 21, 2020 5:59 pm Does anyone know a good way to charge the HV battery with a solar panel? Because I'm planning to have at least one 300W panel on the roof but most of them are 12vDC. I could just charge the 12v battery and maybe skip the DC to DC converter but it would be nice if there was a way to charge the big battery. Maybe there is some bidirectional DCDC converter? Or am I just hoping for too much?

Boost converter. the smaller the boost voltage ratio the more efficient and clean the output. So say a 48 or 92(?) v solar set up would be better.
Many of the hybrid inverters have boost models built in. Prius, Lexus, etc I know for a fact the Gen2 Prius boost circuit can be removed to make it standalone.

having something like this on board would really open up charging possibility’s. Any dc source could charge your van!

Update:
I hooked up the motor (with the openinverter board) to one battery module (86volts)
and got it running in manual mode. Then I connected the model 3 contactors so I got precharge. I also connected a throttle pedal (prius). I actually got the contactors to work fine by setting UDCMIN to 0 and UDCSW to 10 volts under the battery voltage. But when I pressed the throttle the motor went very slowly and where jerking a lot. It also ran in reverse when I connected the 12 volt to the forward pin and vice versa. Now I thought that I should try a higher battery voltage and that it might be the problem of the motor being jerky.

Now to the sad part... I accidentally made a short when I tried to switch pins for reverse and forward. I don't know exactly what happen'd but it started smelling burnt from the motor controller so I disconnected it and took it apart but couldn't find any burnt circuits and the smell only came from the pins. I reassembled it and connected 12v and ground and the Wifi interface plopped up so it had power at least. But when I tried to test it with some low voltage in manual mode nothing happens.

I'm going to take it apart once more and try if I can find something else. But my question is whether the inverter could get damaged by shorting the 12v? Because the controller board seems to work fine.

So it's been some time since my last update but I have tried to work on the bus every weekend.

I have welded extra steel beams under the bus so I can fasten the battery modules. I'm not a pro welder so it took some time to get it right but I'm pretty happy now. It's going to be tight though with only a couple of centimeters on each side of the module.

Next up I started on the batteries and reused the middle part of the model 3 for the big module. I've designed the other twos as well as the top plate so it's going to be completely watertight. I also soldered all BMS cables which was a pain xD.

I'm making tiny steps with only one day a week but at least it's going forward.
/Johannes

Now I started working on the motor attachment and aliment.
I'm just wondering a bit how the angle should be. I think the small attachment on the motor side should align with the car, so that the bolt going through it will be horizontal with the car. And I've also heard that it should tilt something like 20° but I don't know where to measure from haha.

Can you give more details on your pack if you have them, like model year and trim? I've seen (supposedly) 55kWh packs that use the full length of the battery case, so it'd be good to see if there's a way of knowing if a pack has short or long modules. The short modules would definitely be the ones to get.

Hey Johannes,
what a great project! I have nearly the same goal! Here you can see my project!
viewtopic.php?f=11&t=1597

Did you found some more informations for the right angle of the SDU?
My Plan is to have the rear screw 15mm higher than the front screw of the SDU. The reason for that is the constuction of my frame. But the third screw is also horizontal then. More or less;-)

Good luck for you project!
Ben

SRFirefox wrote: ↑Tue May 11, 2021 3:11 am Can you give more details on your pack if you have them, like model year and trim? I've seen (supposedly) 55kWh packs that use the full length of the battery case, so it'd be good to see if there's a way of knowing if a pack has short or long modules. The short modules would definitely be the ones to get.

Didn't know there are 55kWh packs with different modules. My pack comes from a 2019 Model 3 with chassi number: 5YJ3E7EA0KF470123 if that helps.
The short modules are really neat.

/Johannes