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Discussion Starter · #21 ·
Hi Everyone,

Lots of updates to report. The car is on the road, we've made a few videos, and we've even got Level 3 Chademo charging working.

The car is currently making 470hp to the wheels and is very quick. I've implemented a pretty cool PID traction control system in the M150, so the car has great acceleration even with cold tires. With warm tires the thing rips!

Unfortunately it seems our Chevy Volt battery packs are not as strong as they should be. A graph is attached of the current charge versus voltage. You can compare this to the 10kW discharge tests that were done and documented and see the difference. The packs are rated at 45aH, so we should be able to charge 90aH but the pack will only take 72-75aH. The next step will be to discharge and charge each pack individually and see if the problem lies with just one pack.

The rolling resistance with the Pirelli Trofeo R's is pretty ridiculously terrible. But the car's efficiency on the standard tires is approximately 170wH/km at low speeds and around 200wH/km on the highway with the radiator ducts all fully open.

Still a lot of room for improvements. We did see a significant reduction (from about 220 to 200wH/km) by adjusting the drum e-brake assembly as it was dragging a little bit. It doesn't take much to kill efficiency it seems.

There's still a lot of work to be done before we get to the racetrack, but hopefully that will come in the next four weeks or so. Power steering and some brake upgrades first.

Here's the video of the car driving around:

https://youtu.be/Rt4fGIoVMpM
 

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Discussion Starter · #22 ·
Congratulations to Sasha for an amazing build!!
I've never seen anyone building a performance EV this quickly. It is a pleasure to be helping him on the Tesla DU control - I wish every customer picked up things as quickly as he does.

Yup, regen is working. We had to tweak a few things, since everything was still being tested.
The Tesla Drive Unit control is done using UMC Drive 3, by emulating pretty much entire Tesla Model S, to make the Drive Unit happy.

Theoretical maximum of this unit is around 420kW, but that presumes almost no sag of the batteries doesn't account for some of the losses. I'm sure that the final vehicle will get near that :)
<3

Thanks so much for everything Michal, couldn't have done it without you. No way no how.
 

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Hi
If I'm reading your charts properly your batteries are a bit cooler than optimum - I think you want them up at about 30C for max power - could help your sag
 

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I am still very impressed with you project and progress. I had previously seen this thread prior to you getting it on the road and had be waiting eagerly for updates. Then I saw one of your videos on Facebook.....Yeehaaawwww!!!

For my forms of motorsport (motorkhana, hillclimb, khanacross, autocross) I gain major advantages because they are all quite short and are standing starts and often standing finishes. So the electric torque is a massive advantage. Plus I don't need massive battery range. 7kwh has so far proven to be adequate. and all this combines to allow me to reduce my overall weight. WIN WIN WIN (Please note: The afore mentioned wins do not imply actual wins by driver or car, similarity to actual wins is purely coincidental and not intended :) ) All jokes aside though, I have achieved a 3rd place outright and I am still in the developmental phase. My next event is a khanacross this Sunday and I have been waiting for this one for months. It is my best chance so far to prove what the car is capable of.

So I am very interested to see how you progress with your requirements in a road legal car aiming for performance in time attack where you will need more range. Its a brave new world.
 

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Hey,
I'm curious how you got traction control, could you speak a little more to that please?
You have a motec that speaks with the UMC3 by some means to manage amp increase based on feedback from wheel RPM and Motor RPM?
 

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Discussion Starter · #28 ·
Hi
If I'm reading your charts properly your batteries are a bit cooler than optimum - I think you want them up at about 30C for max power - could help your sag
Very good to know! We are always looking for more data on these batteries, if you have any I would be very grateful!
 

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Discussion Starter · #29 ·
I am still very impressed with you project and progress. I had previously seen this thread prior to you getting it on the road and had be waiting eagerly for updates. Then I saw one of your videos on Facebook.....Yeehaaawwww!!!

For my forms of motorsport (motorkhana, hillclimb, khanacross, autocross) I gain major advantages because they are all quite short and are standing starts and often standing finishes. So the electric torque is a massive advantage. Plus I don't need massive battery range. 7kwh has so far proven to be adequate. and all this combines to allow me to reduce my overall weight. WIN WIN WIN (Please note: The afore mentioned wins do not imply actual wins by driver or car, similarity to actual wins is purely coincidental and not intended :) ) All jokes aside though, I have achieved a 3rd place outright and I am still in the developmental phase. My next event is a khanacross this Sunday and I have been waiting for this one for months. It is my best chance so far to prove what the car is capable of.

So I am very interested to see how you progress with your requirements in a road legal car aiming for performance in time attack where you will need more range. Its a brave new world.
Awesome! Very cool to hear about all of the electric cars that are starting to pop up in motorsport!
 

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Discussion Starter · #30 ·
Hey,
I'm curious how you got traction control, could you speak a little more to that please?
You have a motec that speaks with the UMC3 by some means to manage amp increase based on feedback from wheel RPM and Motor RPM?
We have a module that outputs voltage into the Tesla DU controller as modified throttle pedal voltages. So the accel pedal position sensor goes into the Motec, and we use a number of inputs to determine the final power request, and then transmit both the main and the tracking pedal voltage to the Tesla DU. I've mapped out the power at each throttle position and RPM on the dyno, so it's easy to make a request for a precise power value.

That is then sent out as a throttle position to the Tesla drive unit. Very rudimentary but it works really well actually. One day hopefully we can control the inverter directly? Michal? lol.

So in the M150 ECU I can request 200kW, 350kW, whatever and that will be what we get out on the other end.

From that there is traction control logic that just removes power when it detects wheelspin, with a bunch of PID logic and compensations and different aim slip values based on speed, lateral-g etc. It's pretty neat!
 

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Discussion Starter · #31 ·
Another update on the car for you guys, we've gotten it on the racetrack and it performed rather well! Here's the video from the Speed Academy guys:

https://www.youtube.com/watch?v=yyyqqPSIwqA&t=3s

I'll share some data with you all soon, but we use about 10% battery per lap, and we didn't have the cooling system connected properly for this test, so the motor loop was very hot and was likely actually heating the inverter rather than cooling it.

Oh, and regen towing! Filling the battery up in 20 minutes with our pickup truck :) it's all in the video. Enjoy!
 

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We have a module that outputs voltage into the Tesla DU controller as modified throttle pedal voltages. So the accel pedal position sensor goes into the Motec, and we use a number of inputs to determine the final power request, and then transmit both the main and the tracking pedal voltage to the Tesla DU. I've mapped out the power at each throttle position and RPM on the dyno, so it's easy to make a request for a precise power value.

That is then sent out as a throttle position to the Tesla drive unit. Very rudimentary but it works really well actually. One day hopefully we can control the inverter directly? Michal? lol.

So in the M150 ECU I can request 200kW, 350kW, whatever and that will be what we get out on the other end.

From that there is traction control logic that just removes power when it detects wheelspin, with a bunch of PID logic and compensations and different aim slip values based on speed, lateral-g etc. It's pretty neat!
wow, witchcraft!
Michael has my motor controller and i've just ordered an arduino to drive some analogue gauges. I'll learn some programming and hope to link all that together, maybe in that journey i can learn enough to get traction control.

Thanks for the info!
 

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I love it. It is a very impressive build.

Sometimes I wish I had the funds to undertake a more serious EV project like this.

But then again I do get enjoyment from squeezing every ounce of performance from a backyard, low budget car.
 

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Discussion Starter · #35 ·
Thanks guys :)

We took the car drag racing, it did an 11.4 @ 124. We also just did a time attack event and the car performed incredibly, winning its class and every other RWD car at the event as well. Many of the car were full blown racecars, so to beat them with a fully interior comfy street car was very satisfying. Here are some pictures and videos (just links to Instagram for now since I'm too tired and lazy to upload them here).

We've also added power steering, and a three way valve that re-directs the motor water into the radiator (rather than the heater core) when the HVAC dial is set to full cold. This made a big difference on the racetrack, it looks like as soon as the inverter temp goes above 75C or so, the DU starts to impose serious power restrictions.

Drag racing video:

https://www.instagram.com/p/BWTSSkDFxOn/?taken-by=onpointdyno

Tire warmers for time attack:

https://www.instagram.com/p/BW5mCVjFzG-/?taken-by=onpointdyno

Few pics and the final results from the time attack event:
https://www.instagram.com/p/BW6QtYIFNF7/?taken-by=onpointdyno

Track photo:
https://www.instagram.com/p/BW8iMy8FTuV/?taken-by=onpointdyno

And finally some in-car:
https://www.instagram.com/p/BW_WPZel6af/?taken-by=onpointdyno
 

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Discussion Starter · #39 ·
Thanks guys! We appreciate the support.

Since the last update I've gotten the Chademo Charger to work at a few stations that were giving us trouble, that was a big step as I've been fighting to get a few of these stations to work for a while now.

We've also gotten the power steering to work properly, and adding in some different drive modes to change things like the amount of wheel spin allowed (drift mode!), power steering assist, cooling pump levels and duties (the pumps are PWM controlled, so they can run at different flow rates based on needs), and throttle / regen feel and power levels.

I also had the battery area 3D Scanned, so I'll design the bulkhead and then hopefully find someone that can create some kind of mould for us that we can layup a carbon panel on.

In other news, we just had our first baby! Those things are about the only thing cooler than electric cars I think.

Here's the full video of the lap from the Time Attack event we won, along with some more details on the drive modes:

https://www.youtube.com/watch?v=If09etyztl8
 

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Very nice! following since the first youtube video's of the project!

Technical question:
Do you have an idea what the maximum continuous power rating is of the drive unit?

I'm curious as I might want to use the drive unit to power a boat....
 
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