[FIRST DRIVE] Citroën CX and Tesla SDU

[Lood]

Hi,

After reading a lot on this forum (thanks for all the information!) and looking at other projects to find solutions for my problems, I thought lets also document my EV conversion project/build on this forum.

Car:
Citroen CX 25 GTi 1986
Paintwork not very nice, but technical ok. Has been stored for 5 years, and now I thought lets make it electric.

Goal:
Daily driver, range >200km
Assemble the project in a 5,5x2,5m garage box (limited space, no mains power)
I can't weld, I don't have a welder or even electricity so I design the parts to be created without welding, or if not possible to weld somewhere else.
No cutting or welding to the car, I want it to be a bolt in conversion. So when the CX is rusted away, I can put it into another CX

Motor:
Tesla (front) SDU from a 2016 Model X with the Openinverter logic board
The motor works, I have been able to start it up and rev it up.
I have drawn an adapter-frame to connect the SDU to the original CX motor mounts. This is being assembled (welded) by someone now.
The easiest way was to use the original gearbox, and stick some kind of motor to that (There is a CX converted this way), but I wanted a single speed drive, because that’s the beauty of electric motors they don’t need a gearbox. I am using the front SDU because of the limited space within the large subframe of the CX (the rear SDU has a motor mount where de CX steering rack is located).
The SDU is running in reverse (180 deg rotated), so I had to convert the oil pump (as other people documented on this forum). I also rotated the pomp 180 degrees to be able to fit the hoses. I don't know of this will last, otherwise I will fit a external electric oil pump...
For now waiting on the adapter frame, and then sort out the driveshafts.

threaded end marks driveshafts

in yellow the CX motor mounts

rotated oil pump

Battery:
8 Modules from a ID.3 (MEB) 12s2p, I don't know the health of the battery, it was a bit of a gamble but the price was quite low...
They are 6,8kWh each, so total 54kWh. I think this will get me >200km of range.
I will make 2 battery boxes, one in front of the motor, and one where the fuel tank was located. The rear box has been drawn, It is not the final version, but I will be something like this with a central custom cooling plate. The front one I will design when the motor is in.

BMS:
I will use the EVS BMS system, with the original VW CMU. For the current sensor I will used the IVT current sensor
Not yet started on this, but I think the hardware will be straight forward (almost plug and play)

Charging:
Not yet decided, but no DC fast charge (may be later), so I think a ~10kW AC onboard charger

Hydraulics:
Because it is a large Citroen there are hydraulics! The suspensions is Hydropneumatic (actually I converted my CX once to "Hydractive" suspension) with height control, the breaks are hydraulic powered (so no vacuum pump needed) and also the steering is fully hydraulic (a kind of steer-by-wire "Diravi"). So all this need the be supplied with hydraulic pressure and flow. For this I Bought a 12V motor with pump connected (it needs approx. 180bars ). Because the pomp is now electric, the original pressure regulator is obsolete. (the new pump has a built in max pressure limiter). so with al pressure sensor and I can control the pump via a microcontroller. For the steering (which is speed sensitive) I think I will used an electric motor to replace the original gearbox speed-cable.

Dashboard:
I don't know yet, maybe remove the original dials and use a LCD the create a virtual dashboard

Approval:
Can’t find a lot of information about Dutch approval, but as far as I know if you car is build before 1997 then the will only check if the conversion is according to the rules. The rest of the car will be inspected as a normal MOT (APK).


So for now it is waiting on parts (motor frame), and in the meantime designing battery boxes.

Kind Regards,

[johu]

Great project!
My Touran conversion was also done without any welding.

[Age]

Very interesting project!

I'm also planning to convert a CX. However, I'm very short on time at the moment, so there won't be any documentation here until there's any serious progress.

Originally I wanted to fit a GTI Turbo engine, but converting the car to electric has a much greater appeal!

My father and I have built a GTI Turbo with 2 engines in the past. You may know the car, it was sold to the Netherlands in 2004...

My project car is a 1978 Ambulance. But the car still has to be fully restored first.

My idea is to use as many parts as possible without making any changes. That's why I plan to use the Leaf drivetrain. The arrangement of the gearbox and drive shafts should fit in the CX without major changes. I also have a Gen. 2 inverter with OI board.

If I have time, I'll try to see if the complete Leaf batterypack fits under the CX. Of course, the underbody of the car would have to be heavily modified for this. On the other hand, there ist not much metal left there anyway... I would connect the front and rear CX subframes to the Nissan battery.

I don't know how accurate the drawings are, but the battery fits snugly in the trunk on the Break (Estate).



I'm very excited to see how things continue here!

[Lood]

Hi Age, that's quite a challenge to fit the battery pack below the body. Especially when you want to keep the silent-block separation between the subframe(s) and the body. Looking forward to see your project!

[Lood]

After some delay, the motor is in!

Next steps:
1. Connect the hydraulics to the electric-pump. Than I can raise the suspension fully up to check driveshaft clearance.
2. Order some custom driveshafts
3. Design Battery boxes (and order the parts)
4. Find an onboard charger and dc/dc converter!

The space in front of the motor is a little smaller than I had estimated, but it should be able to fit 4 MEB-modules somehow...

My HV-wiring diagram, the dotted lines are for CCS, which I'm not going to do at first, maybe later.
Is this a correct setup? Is fuse F7 necessary?

Kind Regards,

[Lood]

Update:

Battery box design finished, parts are ordered. Both battery boxes consists of a central 10+5mm Aluminum plate where I will mill some cooling channels (in the 10mm plate) and close/seal this with the 5mm plate. At the front and rear of the boxes is a 5mm plate which should provide the strength. All bolted together.
Also simplified the HV wiring, DC-charging removed for now (but reserved space for contactors in the front battery box instead of rear).
For now: waiting on parts...

Front

Rear

[Lood]

New Update,

In the engine bay the main components are in there final position. In front of the SDU there is a battery box for 4 MEB modules. On top of the front battery box the main HV junction box is located (Main HV+ contactor, Pre-charge, Fuses, etc.). In the first picture on the left of de SDU there is the electric (12V, about 200A max.) hydraulic pump, the hydraulic system is now working, and the pump noise is not that bad! Behind the battery box there is a component rack with the 12V battery, space for the Tesla Gen2 charger and Tesla DCDC converter.Also have the EVS BMS with the VW MEB CMUs working now. 1 cell was at 2.69V, charged it for >48 hrs (@200mA) to 3,41V now...

Overview

Custom Driveshafts

Sideview

The fitment of the SDU is a bit tight to the CX subframe, especially to the steering rack crossmember. I will try to move the steering rack 6mm to the rear with some spacers, so there will be more clearance. I have to check if the steering geometry doesn’t change to much doing so.

Next steps:

• Order parts (busbar, connectors, ...) to assemble the battery boxes
• Assemble the HV front battery box
• Create a circuit/program to turn on/off the hydraulic pump to keep the pressure between 145 and 170 bars
• First test drive?

[arber333]

Nice design for boxes.
I would recommend you to add some form of cooling to those boxes. Those LG cells are notorius for thermal instability. That is a lack of cobalt and vanadium. They should be regulated thermaly if you want to use fast charging of more than 0.5C.
If you ask me how i know... i replaced a few of similar LG cells after fast charging destabilised them.

[Lood]

Thanks,
Yes the battery box consists of central 10mm + 5mm aluminum plate. In the 10mm plate there will be cooling channels milled.
But first I will try to make it drive, after that the next step is the cooling system.

[Lood]

I am trying to get it driving for the first time, at half voltage (186V, only front battery). Precharge contactor closes (udcsw=175V) but after five seconds it opens again. The inverter isn’t reading any voltage (udc around 2V). I have had the drive unit working with 48V
I don’t understand why udc is not reading any voltage. I measure 186V on the cables going to the inverter. (viewtopic.php?t=4208)
I will try again tomorrow…

Parameters used

Code: Select all

{
  "boost": 3800,
  "fweak": 230,
  "fweakstrt": 300,
  "fconst": 300,
  "udcnom": 300,
  "fslipmin": 1.5,
  "fslipmax": 3,
  "fslipconstmax": 4,
  "sincosofs": 2048,
  "fmax": 500,
  "dirchrpm": 100,
  "dirmode": 1,
  "ocurlim": 1200,
  "potmin": 16,
  "potmax": 450,
  "pot2min": 16,
  "pot2max": 450,
  "potmode": 0,
  "throtramp": 5,
  "throtramprpm": 20000,
  "ampmin": 3,
  "slipstart": 50,
  "brakeregen": 0,
  "regenramp": 10,
  "regentravel": 5,
  "offthrotregen": 0,
  "cruiseregen": 0,
  "regenrampstr": 50,
  "brklightout": -50,
  "bmslimhigh": 50,
  "bmslimlow": -1,
  "udcmin": 0,
  "udcmax": 450,
  "idcmax": 650,
  "idcmin": -300,
  "idckp": 2,
  "idcflt": 9,
  "tmphsmax": 85,
  "tmpmmax": 150,
  "throtmax": 100,
  "throtmin": -100,
  "iacmax": 900,
  "chargemode": 0,
  "chargecur": 0,
  "chargekp": 80,
  "chargeki": 10,
  "chargeflt": 8,
  "chargepwmin": 0,
  "chargepwmax": 90,
  "idlespeed": -100,
  "idlethrotlim": 50,
  "idlemode": 3,
  "holdkp": -0.25,
  "speedkp": 0.25,
  "speedflt": 5,
  "cruisemode": 1,
  "udcsw": 175,
  "udcswbuck": 540,
  "tripmode": 1,
  "bootprec": 0,
  "pwmfunc": 0,
  "pwmgain": 100,
  "pwmofs": 0,
  "canspeed": 1,
  "canperiod": 1,
  "nodeid": 1,
  "fslipspnt": 0,
  "ampnom": 0
}

cable with green tape is temporarily

[arber333]

Thanks,
Yes the battery box consists of central 10mm + 5mm aluminum plate. In the 10mm plate there will be cooling channels milled.
But first I will try to make it drive, after that the next step is the cooling system.

I am just trying to do the 4 module cooling plate for front and one for the back battery box.
I thought about your idea and i decided not to go that way just because i cant get any mill shop to cut channels into alu plate.
Instead i decided to use 3 plate sandwich. I will use two 8mm plates on the outside for stiffness and i will use 5mm plate and cut it simply by jigsaw to a pattern where coolant will flow from one side to the other. Then 5mm plate will be glued between outside plates and bonded by M5 countersunk bolts.

I will still have to find a TIG welder to weld two 10mm tubes vertically onto one side of the plate.
I currently made two 650mm x 460mm plates and put holes for M10 bolts to fit modules from each side of the plate.
I will report on how it goes .

[Lood]

8+5+8mm is better i think. Looking forward to see your build. My design of 10+5 mm is a little thin.
I am using a 10mm plate where a will tap some threat for nipples to connect the hoses

[Lood]

Some progress, drive unit still not working, but my priority is to charge the batteries first.
The rear battery box is now finished and installed where the old fuel tank was before.
High voltage cabling is in underneath the vehicle, charge port installed.

Next thing to do is installing/routing the low voltage cables.
Then it should be able to charge (I hope).

[Lood]

The EVS-BMS and Tesla Gen2 charger are now wired up. I am waiting on parts for the cooling system.
But the BMS cell voltage is low for some cells. A few weeks ago I assembled the battery boxes and the lowest cell voltage was 3.12 volts.
Today I read the cell voltages (I assume the voltage drop has to do with the low temperature of last week (around 0 °C)):

I got these batteries for a good price (maybe too good to be true...), so this was a bit of a gamble.
But my question is, can I safely charge the whole pack with these low-cells?

[Bigpie]

If you've got a way of charging just those cells, I would (and have on my one of my VW GTE modules) charge those individual cells back up to to be inline with the rest of the pack. I think about 2.45V is around where one of my cells was, and it's been fine for months, but different chemistry I think so YMMV.

[Aragorn]

Bear in mind, these MEB batteries have an active recall running... The symptoms are increased self discharge on some cells due to a manufacturing defect.

It would appear that a few of yours have this issue. It may well be prudent to try and source another few modules and swap them out.

[Lood]

Thanks,
Yes I can charge 1 cell individually, but this will take a few days at 200mA.
What is the minimum cell voltage of the VW-MEB-12S batteries? 2,5V of 3,3V? I assume 3.3V

[Lood]

Update:

The drive unit is working now at high voltage. So, up to the next problem
I thought to have 5 stable battery modules (I started with 8 modules). But again, two modules have cells below 3.3V
Probably, I bought a batch of bad modules; that's why I am going with 5 modules (4 in front, 1 in back) as a start. This also saved approximately 100kg of weight. But this will reduce the voltage to (nominal) 220V. I understood that the Tesla Gen2 Charger will work above 200V, so that will be OK. Only the dcdc has at the label: input 220V–430V. I don't know yet if the dcdc will work at 200V. At a later stage, I can install the other 3 modules and go to 350V.

I am trying to bring them back in line with the other cells (a slow process at 200mA)
Which also means to disassemble the front battery box again:

Wiring loom
In the meantime, I finished the wiring loom. The next step is to make a custom VCU.
Contactors are controlled via the EVS-BMS

Wiring-v01.pdf

(906.29 KiB) Downloaded 25 times

Cooling system
with a loop for drive-unit/charger/dcdc, and a loop for battery (future):

Cooling-DU-Charger-v01.pdf

(87.77 KiB) Downloaded 20 times

First drive
When the battery cell voltage is more or less OK, I will make the first test drive
BUT my engine hoist is also broken; luckily this problem comes with a warranty.

[Lood]

Update;
It is driving!

First Observations:
* DCDC is working via CAN control at 220V. I hope it will also work at 200V
* It looks like the drive unit under load has enough free play (need to check this further)
* SDU first parameter setup is quite smooth
* BMS controls the contactors; this is working OK

Weight incl. driver:
* Front: 959kg (original 981kg)
* Rear: 522kg (original 433kg) --> with 1 module in rear (instead of 4)
* Total: 1481kg (original 1414kg)

Things to do:
* Balance the modules
* Test the charger
* Write software for VCU
* Creating a dashboard (looking for a display 280x90mm)
* New tires (they are square)
* CX Specific maintance (alignment, removing unnecessary wiring, ...)
* The hydraulic pump's mechanical pressure relief value doesn't work
* ...

[Aragorn]

did you buy a pack? Or 8 "loose" modules?

I wonder if they've come out the back door of a dealership that has replaced them under the warranty recall? IE they are ALL faulty?

Seems very odd to have so many failures, it looks like all 5 modules have issues.

In the warranty recalls its unusual to see more than one module needing replacement.

[AMP3R]

Where is the video of driving?