'Another' Porsche Boxster/Tesla EV conversion

[canadasconvert]

Hi everyone. It's taken just under 2 years but I have completed the installation of a Tesla LDU into an 02 Porsche Boxster. The attached PDF takes you step by step through the teardown, experimentation/testing and final build. Be sure to watch the YouTube video at the end of the PDF. Enjoy.

[johu]

Nice, thanks for sharing! Would make a nice wiki page.

Your handling of the batteries made me cringe. You discharged some cells during lower voltage tests and then didn't balance with the rest (unless you didn't mention it). Then took them down dangerously low and charged them super high without BMS surveillance. So some cells were surely above the maximum of 4.2V and below the minimum of 2.5V. These will have capacity loss.

Otherwise brilliant, well documented build

[canadasconvert]

Yes Johnu, you are correct. I learned the hard way how NOT to test and operate batteries. I am making necessary modifications this winter to ensure everything is balanced before operating again with a new BMS.

[canadasconvert]

After a years hiatus from posting, I have a couple of new updates. The first is that the car is running well on a 300V-76 cell KIA SoulEV battery pack. It was originally a 400V-96 cell pack, but through some ignorant stupidity, I damaged two of the original four modules. The pack is controlled by an Orion2 BMS that works very well. So far, the only downside is the reduced range. I put the car to bed for the winter.

In late February as I was a getting ready for this years driving season, I noticed the motor was quite a bit noisier than when I put it to bed. Using a stethoscope, I found the most noise coming from the motor barrel. I did not find any concerning noises coming from the gearbox. I drained the oil and didn't find any coolant in the oil as it was also still red & clear. When I removed the motor cooling pipe end cap, I found the encoder wheel and surrounding area wet and rusty. There is a slight score on the rotor shaft pipe. Since this is a well documented problem with these motors, I know what the next steps are. For rotor removal, can you remove the motor rotor from the stator without disassembling the gearbox? I was thinking of lifting the entire unit vertically with the motor on the bottom and gently "dropping" the rotor out of the assembly. I have seen previous posts that "dropping" the rotor has been done. Any downside to trying this?

Encoder Wheel

Cooling Shaft

[Steve16]

Thank you for posting. I just read your document and watched the video. I'm in the process of a similar build. What did you do to plug the brake fluid reservoir once you removed the clutch master cylinder line?

[canadasconvert]

Further update on motor rebuild - I have order 2 new ceramic motor bearings and a triple lip seal. The motor shaft is a little rough so I have ordered an SKF Speedi-Sleeve to go over the area where the old sleeve ran. I am cleaning up the water damaged parts and getting them ready for reassembly.
See second pic for motor rotor condition.

I am wondering what is the best way to clean the inside of the stator. I was thinking of using alcohol and lots of elbow grease. Do I need to clean out all the grooves in the stator? See first pic.

I have ready a few threads about removing the entire rotor cooling pipe altogether. I’ve seen a DIY solution from Kein Erickson, and two commercial solutions from Revolt Systems & QCC. Does this mean the seal in question is no longer needed? Will it effect rotor cooling?

[Boxster EV]

I recommend the manifold delete.

[canadasconvert]

It took awhile for me to come around to buying the Manifold Delete, but I just bought the Revolt unit last week. Looking forward to getting the car back on the road.

[canadasconvert]

I've installed the Manifold Delete and have put about 100KM on the car. I'm watching the motor temperature and cooling fluid temperature very closely to see if there are any concerns. So far the motor temperature has peaked at 57C after a couple of +100km/h driving stints. The temperature comes back down again and hovers around 40C during normal city driving.
On another item - I am currently running 6 modules (76 cells) of an original 8 module battery pack (96 cells) from a 2015 Kia Soul EV that are made by SF Innovations (27.0 kWh & 355V). Two modules were damaged and cannot be used. The car runs well but its range is limited. I want to add 2 more modules to bring the battery back to 8 modules & 96 cells. I can get my hands on 2 modules that are an upgrade from the original pack that I have. The 2 modules come from a 2018 Kia Soul that had an 8 module 30.0 kWh pack and rated at 360V. Can I simply add these two modules to my existing pack and rewire the BMS to accommodate the original 96 cells?

[johu]

Yes, just manually match the resting voltage to the rest of the pack. The BMS can't balance out large differences

[janosch]

Can I simply add these two modules to my existing pack and rewire the BMS to accommodate the original 96 cells?

How exciting, can you please watch the video I made here and tell me if that's helpful:

viewtopic.php?t=5479


For balancing in I would think:


balancing modules with resistors

• if possible I would put all modules in parallel with big resistors in between
• then reduce size of the resistors when they get very close to each other
• you then have a perfectly balanced pack
• believe you want to do this at relatively high SoC where the differences are the smallest?

And if that is not possible because you can't easily put them in parallel as they are fitted to a car already:


match voltage at high SOC

• try matching voltage of the cells as close as you can at high SoC
• then put the new modules in
• closely monitor afterwards

Is that correct?

[canadasconvert]

Thanks JANOSH. The video was very helpful. I've checked the individual cell voltages of the new modules and they are all within 0.010V of 3.700V. The new modules will be added to the pack over the winter while the car is normally garaged. Stay tuned for updates.

[canadasconvert]

I have connected the 2 newer modules to the Orion 2 BMS. I used the Orion 2 Tap Tool to confirm the wiring was done correctly - good. Now I am back to the original 8 module-96 cell battery. I'm getting ready to reinstall the metal battery boxes in the car and I noticed a slight voltage "leak" between any one of the individual module posts (+ or _ ) to the battery box frame. It starts out at just under 1.0V and quickly drops to 0.1V within 10 seconds. I have isolated the modules so there is no metal to metal contact between the modules and the metal battery box. I did the test with the BMS connected and again with it disconnected. Is this a true voltage leak? Looking for comments.

[tom91]

Is this a true voltage leak

You need an isolation tester that measures in MegaOhms to check for actual current paths, this could just be capacitance.