Electric Motorkhana and khanacross car

Post by **galderdi** » Mon, 02 Nov 2015, 19:39

Hi,

Here is the progress on my motorkhana / Khanacross car.

Motorkhana is a fun, entry level, cost effective form of motorsport. Think of a timed verson of Ken Block's videos.
Khanacross is a little faster and more flowing form of motorsport. Think of a hill climb but without the incline.

Here is an example of a motorkhana:
https://www.youtube.com/watch?v=bLq14ZV8xGE

Here is an example of a khanacross:
https://www.youtube.com/watch?v=PodS9wEFQNg

I am building an electric car to compete in these type of events.
I have been competing in various forms of motorsport for a number of years but I have gravitated towards motorkhana and khanacross. These are relatively low speed, low cost, highly technical forms of motorsport which involve a single car on a track at a time racing against the clock.
Up until know I have used an old Datsun 240z and Nissan pulsar. But about 12 months ago I decided to build something different. I did a fair amount of research before purchasing a DC electric motor in March 2015. Since then I have been progressively building a car from scratch around that motor as the base.

Although I haven’t driven the car I expect the performance to be quite good as the motor normally handles a car with twice the weight. Plus the events I enter are all from a standing start so the brilliant torque provided by electric motors should provide some advantage. I believe electric cars in one form or another are the way of the future for both on and off road. I figure I might as well lead the charge (Pardon the pun).

Technically: The motor is an Advanced DC series wound 9 inch mounted to a front wheel drive gearbox/diff combination. The motor controller is a Curtis 1231C. Although I haven’t taken delivery yet I have ordered 12x 12v Full River High cranking AGM batteries delivering about 150V and about 160AH. The motor and controller can handle 150V dc and 400amps but I don’t expect I will ever use the peak power. Because my events only occur every 3-6 weeks I have decided to charge the batteries individually as I don’t need to charge overnight and a charger for 150V is quite expensive. Range is not a significant issue for me as I only expect to travel around 10km per event and that assumes 2 drivers. I have constructed 3 battery “caddies” to hold four batteries each. This will allow me to have a completely spare set on standby incase I have some fault or just run low during an event. Obviously 150V is quite dangerous so I am applying quite a few precautions to protect anyone who comes into contact with the vehicle.

I am currently on track to complete the build by Christmas giving me a healthy buffer before my first event on Feb 7th 2016 at Willowbank. I have provided some photos showing my current progress. The external appearance of the vehicle will change significantly over the coming weeks as I will be dismantling, painting, reconstructing and adding panels around the sides (just on the 400mm frame you can see) and front motor area.

I am not sure if the first event would be the best to come and check it out as I am sure I will have teathing issues. But I know there will be a come and try event on March 20th. That means you would be able to enter your own vehicle (EV or ICE). It also means I will be able to have passengers on that day for the motorkhana tests(just bring spare undies).

Post by **galderdi** » Tue, 03 Nov 2015, 19:00

I am refining my circuit diagram.
I am including two contactors, the main contactor to take the high voltage/ high current, and a second to connect and disconnect the precharge resistor. The contactor for the precharge resistor will always be connected before the main contactor can be connected.
I am including a dual pole circuit breaker. one side of one pole connected to the -ve side of the battery. The other side of that pole connected to the chassis. If there is ever any +ve voltage on the chassis the first pole will trip and thus will also trip the second pole. The second pole will be providing the power to both contactors. If it trips it disconnects the power.

Post by **galderdi** » Thu, 05 Nov 2015, 17:42

By the way I really need a name for the car. This will be used on the event entry list. I have toyed with the idea of calling it the "Battmobile" and either way I am painting it black with occasional white highlights. But I am concerned that name might be too cheesy. If anyone has a better suggestion I am all ears.

Maybe "Fruitcake" because its full of Current?

Post by **Rusdy** » Thu, 05 Nov 2015, 19:00

Call it "Ohmmmmm"

When someone asked why you named it that way, then you can answer:

"Well, it's electric. Resistance is futile!"

Then they'll diode laughing...

Post by **galderdi** » Thu, 05 Nov 2015, 19:08

I like you're thinking. I could also add some stipes to copy a resistor

Post by **galderdi** » Wed, 18 Nov 2015, 17:20

Here is the latest photo

Post by **galderdi** » Wed, 02 Dec 2015, 21:47

I am using the pedal from a late model Mitsubishi Lancer. I just found that the black bit on the left side was fouling the brake pedal. So I pulled it off. But I can't work out the purpose for this item. It has no wires and doesn't seem to make a difference to the pressure on the pedal. My best guess is that Mitsubishi used the same pedal on other models and on those models attached some sort of sensor there.

Any ideas?

Post by **Johny** » Wed, 02 Dec 2015, 21:52

Modern drive-by-wire pedals emulate cable and mechanical pedals by having a friction system whereby the force required to HOLD the pedal in a fixed position is less than the force required to get it to that position.
It turns out that doing this reduces driver fatigue.
I suspect that you have removed the friction/dampening pad.

Edit: Additional info.
"The pedal is designed to have a certain amount of friction or hysteresis built in. This is done so that the fatigue of pressing the pedal continually is not onerous or becomes fatiguing. It also replicates the friction that would normally be present in a conventional throttle cable as it passes through its housing. A throttle assembly without the correct amount of friction or hysteresis would be very difficult to control smoothly."

Source

Post by **galderdi** » Wed, 02 Dec 2015, 21:54

Cool that makes sense and puts my mind at ease. Thanks for the prompt response

Post by **galderdi** » Thu, 10 Dec 2015, 13:26

Last night was a pivotal point in my project. I had a couple of tests on the weekend which failed. I quickly identified the issue and targeted last night for remediation and a repeat test.
Failure would have put my timeline in jeopardy as I would only have a few weeks to secure and implement any replacement parts (these motors and controllers are not common).
Success would mean I am back on track for the first event on Feb 7th.

The test was successful. I ran the motor on stands without the gears engaged. Then I ran the motor on stands with gears engaged. Then I went for a few test drives.
I still have a few challenges to overcome. Like the accelerator safety not working as expected. Apart from the obvious increased risk it also means when I operate at 30% or greater the motor doesn’t stop spinning when my foot is off the accelerator (Not a show stopper). It also means the motor controller puts out a “Low duty cycle” alarm constantly until I push the accelerator a fair way down.
My Power dial worked absolutely perfectly. On 10% I barely crawl even with the accelerator fully depressed. On 30% it moves the car at what I would describe as adequate speed/acceleration. On 50% it was quite good. I wasn’t game to try it on anything more than 50% because I need to upgrade one of the power cables and I only have the handbrake for the moment.
I need to raise the car as it scraped quite a few times.

This first video is the test on stands:
https://www.youtube.com/watch?v=JfGaBPG ... load_owner

This video is the first test drive. Sorry about the quality but the BattMobile was in Stealth mode. Plus I had the Neighbour’s kid doing the videoing. But you can get a bit of a sense of the performance on the 50% setting.
https://www.youtube.com/watch?v=zDTj-N4 ... load_owner

I hope to have a daylight test video next week but there won’t be any advancement for another couple of weeks.

Post by **galderdi** » Tue, 22 Dec 2015, 19:36

Here are the most recent photos.

and here are some quick tests during daylight. They were a bit slow because it was on wet grass and I only had a handbrake.
The real test will have to wait until Feb 7th

https://www.youtube.com/watch?v=CI3KsInT1R8
https://www.youtube.com/watch?v=SOB0wmiybRw

Post by **mikedufty** » Wed, 23 Dec 2015, 06:38

Would an electric forward/reverse switch give you an advantage in motorkhana? Using the gearbox looks fairly slow.

Post by **galderdi** » Wed, 23 Dec 2015, 13:24

I wasn't exactly trying for speedy changes in this test. In an event I would just slam it in. It might also be a little quicker when the gear lever is bolted down (I am waiting until I can bolt it through the transmission tunel panels)

But you are correct it would give an advantage. But I fear it would place a lot of extra stress on components. Mainly because it will be too tempting to flick the switch before coming to a complete halt. However when I next compete in the Australian championships I might temporarily make that addition to try and be as competitive as possible. That type of event warrants the extra risk. For now I just want to get the thing running, reliable and iron out the bugs.

One of the first mods I want is to make some replacement front top control arms with a camber adjustment. At the moment the driver side is on positive camber and the passenger side is slightly negative. It won't matter for the first event but for the Khanacross on Feb 21st and for the QLD championship round on March 20 I will need that extra grip.

Post by **galderdi** » Tue, 02 Feb 2016, 21:08

Here are the latest pics of my project. It is now about 99% complete. Which is a good thing because the first race is this coming Sunday.

I just need to:
•        Assemble the final (3rd) set of batteries
•        Bleed the brakes one more time
•        Do a wheel alignment
•        Try to sort out a problem with my Battery Management System
•        Hopefully if I get time I still need to put some trim around the panels to tidy up the rough edges

Post by **galderdi** » Tue, 23 Feb 2016, 22:23

So I had my second event in the Electric car on Sunday. I hadn't fixed the batteries yet, so I wasn't expecting much. I was really treating it as another opportunity to test the car and identify anything else that needs to be modified. The event was a Khanacross (similar to an Autocross). The car performed almost exactly as I expected. It would launch fairly well (about 0.5 G) but then after the first 10 seconds I would struggle to get more than about 0.1G and sometimes I was only able to maintain current speed with no acceleration at all. You can see I was forced to over compensate in the corners in an attempt to maintain speed. But my suspension needs work as its not turning in very well. The car was far from the slowest on the day and showed a tonne of potential. Even just fixing the batteries (without altering the suspension) would probably have put me up amongst the front runners.

Really I have three things to change:
1.Batteries - If I can achieve consistent acceleration throughout the course I will be awesome.
2.Camber - The right front is at 0 degrees will the left wheel is at about 3 degrees. I think matching them both at 2 or 3 degrees would be my best guess.
3.Ackerman angle - The chassis is about 10 inches shorter than the doner car where I sourced the hubs. So the angle of the front wheels when turning is far from correct. As I corner the outside wheel is trying to turn significantly more than the inside wheel. This means they fight against each other and the outside wheel scrubs and pushes resulting in severe understeer.

I need to have these sorted by the 1st round of the Queensland Motorkhana championship in Rockhampton 19/20 March. That gives me 3 weekends to work with. As that event is a significant milestone I will make that the final progress report.

I had my GPS camera this time and its giving me some really useful data. Each video is about 90 secs but I don’t advocate watching them during work time.

Thanks Greg

https://www.youtube.com/watch?v=hlGXK6u4hDU
https://www.youtube.com/watch?v=F8C-HSnuYn0
https://www.youtube.com/watch?v=4ZpKkELHcjk
https://www.youtube.com/watch?v=-lry28gNfLk
https://www.youtube.com/watch?v=qqtAcHh0q5I
https://www.youtube.com/watch?v=j40CQkR_BNY

Post by **galderdi** » Fri, 12 Aug 2016, 18:49

Here is a video from the latest event (Motorkhana)

The car is better at Khanacross but motorkhana is still fun.

http://www.youtube.com/attribution_l...m-upload_owner

I have created a new Youtube channel and Facebook page:
https://www.youtube.com/channel/UCnE...ehgrxXcohzWiYQ
https://www.facebook.com/fullchargemotorsport/

Post by **galderdi** » Fri, 19 Aug 2016, 23:21

Sorry I realised that Youtube link is incomplete. Please try this one:

https://www.youtube.com/channel/UCnEGxo ... xXcohzWiYQ

[ Edited Coulomb: made link clickable ]

Post by **T1 Terry** » Sat, 20 Aug 2016, 00:34

Looks like a lot of fun and seems to go well enough. How much more acceleration potential does it have?

T1 Terry

Post by **galderdi** » Fri, 02 Sep 2016, 19:05

It's difficult to quantify how much more potential it could / should have. But think of it this way.

This setup is normally used for great results in road cars up to around 1200KG. I would expect that to mean 0-100 in say 8 seconds and a top speed around 110kmph assuming no gearbox is used.

In mine I have 500kg but have only managed 0-100 in around 8 seconds and its still maxing out at 90-100 kmph even though I still have 2 gear remaining (I am not getting to 4th or 5th gear). I have only used around 25kw of peak power. The motor is theoretically capable of 75kw, but thats assuming max volts and max current at the same time which will never happen. I think realistically I should expect more like 40KW. It doesn't sound like much difference but I think it will make a noticable difference to the results as I should then be able to accelerate in 3rd and 4th (currently I can't).

The next event is a Motorkhana this Sunday so I will be trying a few changes to see if I can improve the output. The most likely improvement is a change of accelerator to make sure I have the full range. I am not overly confident.

At the moment it tops out at around 90kmph in the straighter sections of khanacross between the turns. Even without any improvement that performance should place me in the top 1/4 of the running field. If I can increase the acceleration slightly and achieve a top speed of 100kmph I should be in line for a podium position.

Post by **T1 Terry** » Sat, 10 Sep 2016, 03:12

So how did you go on Sunday? From 25kW to 40Kw should make quite a big difference in acceleration, more voltage would allow a higher motor speed to achieve the 100km/h without the need to change as many gears, surely that would be an advantage

T1 Terry

Post by **galderdi** » Mon, 12 Sep 2016, 17:48

Didn't go to plan.

The car and driver were performing reasonably well. Although the car performance was OK it certainly wasn't up to the level I would expect from the combination. But it was still an improvement on previous attempts. I was fairly competitive, at the time I expected to be top 3. It turned out to be 8th which was a surprise. But the biggest issue was a suspension failure on my last run of the day. It allowed my rear left wheel to literally fall over. It caused me to hit a flag. At the time I thought it was driver error and I continued driving. I heard scraping but thought it was the base of the flag caught under the car. It turned out to be the wheel draging on the ground. I managed to drive another 30 meters before the system overloaded and blew my fuses. After being pushed off the course I took some time to assess the result. It was obvious the fuses were blown. I walked to my tow vehicle and grabbed my spares. It took a few minutes to walk there and back and replace the fuses. But what I didn't know was the precharge resistor was also blown. When I turned the system on again I beleive a surge blew my controller. The motor immediatly attempted to spin (even though my foot was not on the pedal and the saftey relay was deactivated) and within about .25 of a second there was a rather loud bang. I have now done some testing and I think the controller is dead. I see a short circuit across the battery side of the controller. But I think the controller was always faulty, it never behaved as I would have expected. So I have ordered a new controller. I am going with the 1000amp variant to make sure I have no chance of overloading it. I am aiming to be installing it by the second week of Oct and ready for the next event which is Nov 6th. This one is a Microprocessor controller so I will have a lot more visibility and control to make sure I get the most out of the system. I will provide another update mid October.

Post by **T1 Terry** » Mon, 12 Sep 2016, 20:35

Not a good thing to happen, but these things are part of building a more reliable and competitive unit so just need to be accepted as part of the learning curve.
looking forward to a better set of events for the next outing. No doubt there will be a fair bit of tuning to do so just finishing will be the aim next outing, good luck with it.

T1 Terry

Post by **galderdi** » Mon, 12 Sep 2016, 21:01

Yes, other than the extra expense I am not too upset.

Luckily the failure on this event was on the last run. At the event we did two attempts at each test and the best time from each pair counted. So I really didn't lose much.

The past two events have been motorkhanas. The car is unlikely to ever be competitive at motorkhanas because it is too big and too heavy. Motorkhanas are suited to cars around 300kg and with a wheelbase a bit bigger than a go cart.

My car is much better for khanacross which is a bit faster and more flowing. The next event is a khanacross, so I am really aiming for a good result there.

Post by **galderdi** » Wed, 14 Sep 2016, 19:14

I have lined up a new controller. I am going for the 1000amp variant. I believe I will be able to easily double the power compared to how it was performing before. It will be about a month before I will have it all installed

Post by **galderdi** » Wed, 24 Apr 2019, 11:17

Its been a while since I last posted here. To be honest there really wasn't that much interest from this group. But anyway I figure it is probably time to post an update as a lot has changed. I ditched the old chassis as I was losing too much acceleration through front wheel drive wheel spin. I have now reused almost all my components in a new rear wheel drive chassis. It is going great. I still have some work to do tuning the front suspension to maximise the grip. But largely it is just a matter of tweaking now. I will post some photos from recent events shortly.

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