# EV Crosskart



## MasterRickard (Jul 24, 2014)

Hi,

I'm new here, but I have been lurking around for a while.
I drive someting called crosskart which is like a minibuggy and its a motorsport here in sweden. And as race gas is really expensive and a bit hard to get, I thought why not do an E-crosskart? 

The criteria I have is that it must preform as well or better than the ICE karts which have tuned 650cc single cylinder engines with around 90hp and quite alot of torque, and the regulations say that the minimum weight is 295kg including driver, so most weigh in at around 300kg. 

One heat is usually just around 5min long, and a final maybe 7min, so I guess the range does not have to very long, maybe have a small cell pack that you swap between heats? to keep weight down.

I'm a pretty good mechanic and I work with building electrical systems for trucks so i'm not worried about that, tho I lack some expertise on electric motors and most of all the controllers.

I'm not made of money, but I'm not in a hurry either so if the price goes up, the time for the build just gets longer.

I have looked on lots of different parts but I haven't really locked on to anyting yet.

So what do you think? a good idea or just stupid? Is it still possible to get that kind of prefomance and stay close to that weight?
Any advice on good lightweight engines?

Best regards.


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## dougingraham (Jul 26, 2011)

Do these vehicles have a transmission? How much torque do the ICE motors have and what kind of RPM range on the ICE?

I think your problem is going to be batteries. If we match the 90 hp (67 kw) of the ICE that tells us we need a pack that can do 67 kw. To keep the weight down you probably want to be able to completely discharge the pack in less than 10 minutes which means a 6C continuous discharge rating. If you want to cross the line in 5 minutes with the pack dumping then you would need 12 C continuous. So that is something to aim for. If you want to do some regenerative braking and recover some energy then you want an AC system. You can get close to 90 HP with the inexpensive HPEVS motors with Curtis controller. You can go the HPEVS web page and study the dyno plots and see if anything looks usable. My gut feeling is that these would be on the low end power wise for what you want to do. But it may be that you get so much torque with the electric and you rarely use the 90 hp with the ICE that these will work.


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## Karter2 (Nov 17, 2011)

read this for inspiration, and let your imagination adapt the build ideas to your specific type of buggy.
http://www.diyelectriccar.com/forum...k-therapy-racings-golf-cart-based-104481.html


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## MasterRickard (Jul 24, 2014)

Yes, most have 5 or 6 speed sequensial transmission and then chain and gear final drive, just like a motorcycle, my thought was to skip the trans and just run the final drive.

Not so sure of the torque figures as most people talk hp, but the stock torque is around 65nm / 48 lbft so a bit more than that. They redline around 7-8000rpm.

12C continious is not that much is it? sounds doable to my (inexperienced) ears. But I figure this is where the most money goes.

From what I can see on HPEVS webpage, I would agree that I would probably be a little down on hp but maybe the much higher torque would make up for that.

Apart from regen, is there any other pros over DC with the AC?

Thanks for the inspiration thread, intresting reading.


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## Duncan (Dec 8, 2008)

AC v DC
Main issue is cost
DC can be done cheap - used forklift motor
But even if new is much cheaper for lots of power,
$7000 (warp 9 Soliton) can give 300hp
AC for the same money is 35hp???

For a competition machine look at RC batteries - some of them are 120C !


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## Karter2 (Nov 17, 2011)

Even with that 67kW motor maybe only using 40kW average , you will need a 10kWhr pack for 15 mins run time.
So, say you run 200v (Warp 9 motor), that would dictate a 50Ahr pack.
Using something like 50C, RC lipo . 5Ahr 6S packs ( 1kg each)..
would need 9 series packs and groups of 10 parallel. IE 90 packs total @* 90 kg .* ( and you wont find much lighter !)
67kW @ 200v draws 335amps.
on a 50Ahr pack that is only just 7C... easy !

Actually i suspect your problem may be weight !


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