Electric kart

Electric cars, trucks, ATVs, NEVs - things bigger than a motorcycle.
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nuxland   100 W

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Electric kart

Post by nuxland » Apr 13 2015 2:15am

Took a Tony kart without motor and installed batterys and electric motor.
Motor: GM 10kw 48V and 100kv I think.
Battery: 16x 60Ah Winston
Controller: GM VEC500 48V
Kart.jpg
Motor speed with wheels of ground was 4700rpm. Rear wheel size is 11" :) and theoretically top speed should be 81km/h.

First day in the track had a 15 teeth motor spocket and 45 teeth rear spoket, this made a 3 times reduction of motor speed and 3x increase of torque.
Max speed on the track was 73km/h, so motor rpm was 4300. Current was limited to 200A on controller. As the speed was not enough spockets were replaced :)

Next try was with 18 teeth motor spocket and 36 teeth rear spocket, this made a 2 times reduction, and with 4300rpm max speed should be 112km/h.
But actually max speed was 93km/h so motor speed was only 3600rpm. Result of this test was that motor controller overheated after 12km of racing (12 laps).
Max current was increased from 200A to 250A also, but it overheated even with 200A. Motor was only slightly warm.
Video on that day: [youtube]https://youtu.be/ypJ3Iw4WwiQ[/youtube]

Installed a big heatsink beneath controller with active cooling to keep the controller heat down, but have not had time to test it.
Heatsink size compared to controller:
Controller.jpg
and here installed with coolers:
ExtraCooling.jpg
ExtraCooling.jpg (197.72 KiB) Viewed 1947 times
Also increased rear spocket size to 40 teeth, so right now I have 2,2x reduction and should get the same 93km/h with 4000rpm but have more power for accelerating.
Are waiting for analogger to be delivered so I could see my motor and controller temperature compared to current.

It seems that 48V is not enough :) Was thinking of adding 4 more elements to increase voltage to 60V. I know that controller can handle it, as it is universal from 48V to 110V.
But how can 100kv motor handle 60V, it makes the maximum rpm to 6000 without load? With load and 4700rmp is good enough to me.
Last edited by nuxland on Jan 15 2018 2:24am, edited 2 times in total.

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electron bom   1 W

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Re: Electric kart

Post by electron bom » Apr 13 2015 7:24am

That thing looks quick, 93km/h is fast to me. What top speed do you think is ideal? How does it compare to the gas karts in terms of acceleration?
Chemistry is neat!

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Apr 13 2015 8:09am

Rotax Max with 23kw engine got 110km/h in the same track and their lap (964 meters long) time was 10sec faster.
I hope to brake 100km/h barrier :) But I do not think it is possible with my current 48V setup.

knighty   10 kW

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Re: Electric kart

Post by knighty » Apr 13 2015 8:19am

if I were you I'd be thinking about running 96v

the increased rev range means you could change your cogs again, so you have 110kph top speed (or whatever you need)

but also increase acceleration


but that all depends on your motor/controller working with the extra power without overheating

200amps at 48v is 9.6kw

200amps at 96v is 19.2kw - so you only need to run 100 amps for same power at motor

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 17 2015 12:49pm

Was racing with 9hp hobby karts last week and it is faster that reqular 9hp, but slower than tuned 9hp kart.
But this 10 laps rised one more problem, it seems that controller was reducing current because motor temp.
In VEC500 controller software there are 3 settings for motor temp: level 1 120 degrees celcius, level 2 130 degrees and shutdown 150 degrees.
It seems that GM HPM10 has very poor cooling because from outside motor temp was only 33 degrees of celcius.
Starting from 7th lap current was lowered from 250A to 220A and then after 1,5 more laps to 200A.
I managed to use 27Ah with ~12km (10 laps + 1 cooldown lap), it makes 2,25Ah per lap.
RaceRender and analogger together make very good analys tool :D
http://1drv.ms/1RXWUHC

Meanwhile I have opened controller and there are 75V fet's inside :cry: so I will add only 4 cells to total 60V.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 31 2015 9:25am

I have now installed 4 more cells to my 16S pack and have now 20S pack. I have driven over 50km with it and controller is working ok with 58V and 225A.
Was again racing with hobby karts last week against 9hp tuned version. And I still have a motor overheating problem :(
I lowered battery current to 225A because of voltage rise from 48V to 60V.
Here is a video https://youtu.be/c6om_p3X9xI of one race where controller reduced battery current from 225A to 163A and loosing 3kw was enough to let gas powered kart to pass us.
Then after 1,5 laps motor somehow cooled down a little and controller gave back the power but in the end we braked to heavily and made a spin. It seems I need front brakes also.
Controller temp is under control because of this big heatsink behind it (its 30 degrees). Do not look lower temp gauge, because it is motor outside temp not inside.
Last edited by nuxland on Jan 15 2018 2:27am, edited 1 time in total.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jun 05 2015 6:22am

There is now forced airflow to the motor. Fan motor is 48V/45w and capable of 270 l/s of airflow.
I designed the scope so that when driving it directs outside air also to the motor.
Here is picture of my vision:
AirCool_Vision.png
And here is actual output:
AirCool_Real.png
There is also protective aluminium web on top of the blades:
AirCool.png
It added about 3kg to the weight, so I need to loose 3kg :)

SlowCo   10 kW

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Re: Electric kart

Post by SlowCo » Jun 05 2015 7:11am

Hahaha, that's some serious air cooling :!: :shock: 8)

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riba2233   1 MW

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Re: Electric kart

Post by riba2233 » Jun 05 2015 7:20am

It's well known that these golden motors have terrible heat path from stator to outside air. You should have bought motenergy/mars 0913 instead, it's open design and air cooling would really help in that case.

voltereta   10 µW

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Re: Electric kart

Post by voltereta » Jun 05 2015 7:14pm

I am going to start the same project than you... And now I am looking for the motor...

GM also have water cooling system for this motor, did you consider this type of cooling?

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riba2233   1 MW

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Re: Electric kart

Post by riba2233 » Jun 06 2015 1:49am

Liquid cooling - also not much better option, because of poor heat transfer. Just buy mars, they cost the same.

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liveforphysics   100 GW

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Re: Electric kart

Post by liveforphysics » Jun 06 2015 2:02am

They go pretty hard for a few laps with enough controller. Then you gotta back it off or you cook them. I was feeding mine 660A phase current on a bicycle that went pretty hard.
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voltereta   10 µW

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Re: Electric kart

Post by voltereta » Jun 10 2015 5:23am

Nuxland, which range you can do with 60A?

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jun 18 2015 1:34pm

Will try to install forced cooling to blow air inside of motor because cooling motor outside did not help at all :evil:
1. Make holes in both side of cable box.
2. install intake scoop to mount two fans.
3. Red thing in middle of the wires is for redirecting air inside motor and not directly throught cablebox.
4. install output scoop so I can put some metal filter there (so that small particles do not enter from there)
mootor_cooling.png
mootor_cooling.png (128.73 KiB) Viewed 6486 times
I hope that I can push 27 l/s through the motor, because there are very little space in the motor (1,3 liters of air in my calculations).
Can someone calculate how much heat can be removed with this?

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jun 23 2015 5:45am

Work in progress :D
cooling1.jpg
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cooling2.jpg
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cooling3.jpg
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cooling4.jpg
cooling4.jpg (133.07 KiB) Viewed 6346 times

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jul 01 2015 12:12pm

Was racing with this motor mod and now I think that the controller is my bottleneck.
Because after just one lap max battery current went from 290A to 240A and were there till the end of race (13 ~800m laps).
I have a multimeter showing motor windings thermostat ohms in the weel (GM has two of them and I'm using the spare one) and it showed 750ohm, it should be 70-80 degrees of celsius only.
And also at the 10th of lap controller was shutting itself down like when I did not have cooling for it. So it seems that 45 degrees in heatsink is maximum for my controller.
DirectAirCooling.jpg
DirectAirCooling.jpg (100.34 KiB) Viewed 6247 times
In this video lower temp is controller heatsink and upper temp is air temperature coming from motor. Outside temp was 20 degrees on that day.
https://youtu.be/GgJ4wN15At4 Controller disabling output current is when current went to 0A after I pass kart nr 19. Then I had to release throttle and current came back and went away multiple times until to the end of race.
Last edited by nuxland on Jan 15 2018 2:32am, edited 1 time in total.

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riba2233   1 MW

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Re: Electric kart

Post by riba2233 » Jul 01 2015 12:25pm

Buy a real controller.. I don't get why would anyone buy GM controller.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jul 23 2015 5:55am

My plan is to get at the end of August Sevcon 72V Gen4 Size6 controller and see what I can get out of that motor then.
Right now 14kw is the max my controller can input to the motor and that is to little for a 149kg + 86kg of mass.

Installed front brakes last week and braking improved like 100% :D
Front_Brakes.png
Some fun in the track also https://youtu.be/a1wnrENzBK0
Last edited by nuxland on Jan 15 2018 2:34am, edited 1 time in total.

voltereta   10 µW

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Electric kart

Post by voltereta » Jul 23 2015 9:29am

How long time you can drive the kart with one charge?

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jul 23 2015 10:24am

It is average 2,5Ah per 1km lap. Right now in 10th of lap my controller overheats. But batterys should last 20 laps it makes 50Ah and after that there is 10Ah left in the batterys but voltage drop is too large to race anymore :)
Average races are 10-15 laps so I have to much Ah and wasting weight that way.

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nuxland   100 W

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Re: Electric kart

Post by nuxland » Jul 29 2015 8:18am

Finally 100km/h in a race track, just for a moment though :D
20150728_Tabasalu_100.jpg
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Video also: https://youtu.be/0pyk49RWJSM
Last edited by nuxland on Jan 15 2018 2:35am, edited 1 time in total.

Hillhater   100 GW

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Re: Electric kart

Post by Hillhater » Jul 31 2015 1:32am

Swap those Winson cells for some RCLipo to cut a bunch of weight.
That will instantly improve your acceleration, speed and cornering = much reduced lap times.
If you upped the voltage at the same time, (more rpm range), you could increase the gear ratio and reduce the current draw to help the motor stay cooler too.
Do you know how to set up the chassis to suit the track/ tires etc ?
There are many adjustments on a kart that can have a huge effect on lap times.
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lizard   100 mW

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Re: Electric kart

Post by lizard » Sep 08 2015 2:41pm

Really nice Kart you have there.

Regarding RC lipos: Maybe have a look at the Hobbyking Turnigy Multistar lipos. They seem to be getting quite popular lately in the RC community. They don't have the highest C-Rating but they are available in large capacities (for rc lipos) and are lightweight and cheap.

Only drawback I can see is that lipos can burn like crazy if something goes wrong ...

kenwood96   10 W

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Re: Electric kart

Post by kenwood96 » Sep 25 2015 12:30pm

Turnigy lipos and water spraying could help a lot...

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nuxland   100 W

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Re: Electric kart

Post by nuxland » May 04 2016 6:18am

It was busy winter, building my new 100V 4kwh battery pack.
But now kart has new controller also and is driving way faster.
Have not had time to go to the track jet :(
Kart2016.jpg

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