Electric Karts

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Crash
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Post by Crash » Mon, 01 Jul 2013, 06:08

I can't help thinking that it is about time we started to see electric kart racing starting to appear in Australia. with the eFXC motorbike racing demonstrating feasibility of an electric racing formula and an international open wheeler formula not far away.
The question I have is should electric karts be just the same as a sprint kart with the two stroke motor swapped for an electric motor and the side pods filled with batteries, or should a new technology have a fresh approach? What is the best and safest way to mount batteries in a kart chassis? These days with easy access to online cnc machining is there any reason why a kart shouldn't have a little wishbone suspension setup? My radio control car does. Is two motors and a split axel better than one motor and a solid axel? If was a class with a standard programable controllers, this could provide new opportunities for keeping a level playing field, or even to have the option of handicapping.
Has anyone else thought about this? What would you include in the design of a new electric kart?


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Post by Adverse Effects » Mon, 01 Jul 2013, 14:31

karts dont have all the extra stuff like suspension and diff's to keep the kart as light as possible

it would be almost 2 times as heavy with all the extra stuff on it

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Post by Crash » Mon, 01 Jul 2013, 16:15

People said that about mountain bikes when they started to emerge.

I wouldn't expect a suspension system for a kart to be anywhere near as heavy as motor or batteries.

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Post by Adverse Effects » Mon, 01 Jul 2013, 16:38

putting a full suspention system on a kart would easly add 80% to the frame wight if not more

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Post by Crash » Tue, 02 Jul 2013, 07:05

A 125cc kart is reported on karting sites at about 90kg including chassis and motor.

Mtb coil over spring shock units are around 500g (total 2 kg) each
8x aluminium arms which can be easily cut from ali plate as size is small adds about another 1.5kg,
bolts and joints allow about 500kg
Total of about 4kg. Other items are common to current kart eg spindles or are fairly nominal additional weight eg connecting lugs on chassis. This is about a 5% increase in weight. Extra complexity may be an issue.

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Post by acmotor » Tue, 02 Jul 2013, 07:46

Crash, I like your thinking (despite the 500kg typo).
Is it that most karts run in established classes ?

The fixed rear axle (spool) on the karts I have ridden deliberately limits cornering forces due to breaking traction. This means a kart will slide and spin out well before there is a COG issue and tendency for kart to flip over. Is this the intention ?
Still, top end karts have diffs, don't they ?

Going to AWD and independent suspension would make a kart vastly faster around a track but more catastrophic when it lets go ?

Anyway, an electric class with all the good design would be on its own at present. Need to make more than one e kart along the lines you are thinking otherwise it will have nothing to race against !
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Post by Adverse Effects » Tue, 02 Jul 2013, 16:12

i did state "FRAME" not all up

not to mention when your ass is less than 1 inch from the track you dont have much use for suspention

you then say so we can fix that just jack it up a bit

that would make the COG to high

karts are made the way they are for a reason

primarily best performance secondly cost of frame manufacture

think about it

125CC pushing 90Kg
125CC pushing 100KG
125CC pushing 110KG

what one of thos is better?

and 5Kg will make a BIG difference in performance

there are lots of other reasons but i couldn't be bothered going in to them
Last edited by Adverse Effects on Tue, 02 Jul 2013, 06:14, edited 1 time in total.

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Post by acmotor » Tue, 02 Jul 2013, 16:28

Is there scope for the electric fruit of an ekart to have a lower COG compared to an ICE kart anyway ?
Low profile batteries mounted that '1 inch' above the track and emotor COG only '200mm' Image above track ? ICE can't achieve that.
I am impressed by the battery pack on a Tesla model S .... talk about low COG !
Suspension can take several forms... one is that wheels cannot rise (saving your 1 inch) but can go down to follow terrain. This achieves wheel on road traction. But true, a flexible frame may have the same result.
AE points out the cc class factor. There would need to be a e class based on kW or battery capacity ?
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Post by Adverse Effects » Tue, 02 Jul 2013, 19:36

acmotor wrote: Is there scope for the electric fruit of an ekart to have a lower COG compared to an ICE kart anyway ?
Low profile batteries mounted that '1 inch' above the track and emotor COG only '200mm' Image above track ? ICE can't achieve that.
I am impressed by the battery pack on a Tesla model S .... talk about low COG !
Suspension can take several forms... one is that wheels cannot rise (saving your 1 inch) but can go down to follow terrain. This achieves wheel on road traction. But true, a flexible frame may have the same result.


lowering the COG by 30mm wont make up for the fact that your now 2 times the weight from the HUGE slab of battery's and also you would need to raise the driver for the battery's to be under him
AE points out the cc class factor. There would need to be a e class based on kW or battery capacity ?

ok so i said it wrong
( i am just useing an arbitrary figure of 8Kw but it applys to any amount)
8Kw pushing 90KG
8Kw pushing 100Kg
8Kw pushing 110Kg
Last edited by Adverse Effects on Tue, 02 Jul 2013, 09:44, edited 1 time in total.

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Post by woody » Tue, 02 Jul 2013, 19:51

There is a track in Auckland (Formula E) which has electric karts only.

They are quiet, fast, not smoky or stinky. Made in Italy, ~NZ$18K each. 4 optima yellow tops are in the pods and charged at ~100Amps.
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Post by Crash » Wed, 03 Jul 2013, 04:56

OK point taken, suspension may not the best idea but its also not the main point of the thread. What batteries, how many, where to mount them, what motors, one or two and how do we get a few electric karts built and start racing.

If there are ideas such as suspension that are contentious, what better way to prove a point than to have a chance to put it up against other karts to try and prove a point? It would certainly be a great motivator for me but at the moment everything other than a standard sprint kart design is not permitted so there is no progress? Maybe current ice karts have settled on the optimum formula over the years so no need to innovate? (skeptiscm) With new tech electric karts is there a greater need and opportunity to try new ideas.

ACM point that fixed rear axel limits cornering forces is an ideal case. A twin electric motor system driving rear wheels independently is simple and avoids diffs, should provide greater cornering grip andt could balance additional weight of a battery pack.

Keep in mind that we would be looking at a separate electric kart or competition, not trying to compete directly with existing classes, so the playing field is still level and you wouldn't expect a totally new competition class and technology to be competing directly with a mature and well developed racing industry.

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Post by Crash » Wed, 03 Jul 2013, 04:57

Is Formula E karts in NZ a hire kart track or a club track for privately owned racing karts?

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Post by Kieran » Mon, 25 Aug 2014, 04:27

Formula E in NZ is a hire kart venue.

The frame of a sprint kart is designed to flex, providing some lift of the inside rear wheel to assist cornering. That is my understanding, anyway. This design is also probably to keep kart racing more simple by avoiding the complexity of suspension. It is an entry level form of motorsport so the idea is to make it more accessible to more beginners. I would suggest sticking to a standard sprint kart frame to keep that relative simplicity.

Could the electric bike racers provide some advice? How did they get their racing off the ground? I'm guessing they have a separate category at normal bike meetings?

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Post by pottz » Mon, 25 Aug 2014, 17:10

I'm only a rider in the EFX-C but I think a Kart series is a brilliant idea, when I just found this thread I was actually looking for electric Kart info for something to get into with my son later on.

With the bikes it's a bit different and we have very few rules and it's very much a technology and manufacturing series more than a rider series. Big (relative) dollars are spent on custom ground up builds like Voltron-Evo etc. Bikes are extremely complex and due to the development of years of big manufacturer racing we arnt quite at the stage of being competitive with the petrol models (it won't be long at all if Voltron is an indicator)

For Karting you can simply (again relative) replace the petrol motor with an electric one and expect similar handling. I'd almost be inclined to start with a very limited class. I'd make something that is comparable to a mid level class of petrol Kart and keep the rules simple, don't try re invent the wheel. Possibly limit the torque/power output to the same as the petrol class and have a minimum weight of kart and driver combined. This way there shouldn't be any reason you can't run with the petrol models. A plus side is as a sub class, you will find clubs more accommodating to letting you join in rather than them having to put on a separate race for the couple of electrics.

I'd also look at making a cost effective, off the shelf one people can buy and get into racing simply and cheaply. Market the simplicity, lack of rebuilds, parity and cheaper running costs. Combine this with good close racing and I personally would be buying one and getting the young fella into it ASAP. Think almost like current motorcycle 250 production racing.

Then again, that's just thoughts from a rider so take my 2c lightly.
Last edited by pottz on Mon, 25 Aug 2014, 07:13, edited 1 time in total.

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Post by Kieran » Mon, 25 Aug 2014, 19:21

Thanks for your enthusiasm Pottz.

The only off the shelf options I'm aware of are geared toward hire kart venues and seem quite expensive. The only "kits" I'm aware of are Ausemoto's <$4,000 kit and EV Power's $2,770 kit (this price may assume assembly by the buyer). I've only read about these two options and really have little idea if they are commercial realities ready to buy right now. Perhaps the parties would be willing to comment on that themselves?

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Post by Bluefang » Tue, 26 Aug 2014, 01:12

Its like electric bikes, the lower the power the cheaper it gets. Only problem is the safety factor of been able to run it on the race track.

With the superbikes all the refs are trained what to do in a emergency. I don't think you would be able to put a electric kart on a track with normal race karts even in the smaller clubs because of the whole red tape issue with insurance and affiliation with the racing organization. Hence the reason its in hire places. But it is super easy to build a kart up with a large red off switch :)

I might try again once i have some spare funds, everything is cheaper and better now so maybe we can swing a local club or 2 to the idea of a electric kart sub category. Once my new build is done i was heading out to a dirt bike track too. I dont race karts or bikes so its always good to hear from people who actually do.
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Post by Kieran » Fri, 29 Aug 2014, 19:39

Is the idea of using a hub motor as the electric motor on a sprint kart impractical? I suppose the casing would be wrong for bolting on to a bracket on a kart frame?

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Post by jonescg » Fri, 29 Aug 2014, 20:34

Like Pottz says, the eFXC series is still a designers/builders playground. It's at that stage of development where some form of competition is needed to motivate us to build better machines. Eventually, some winning formula will emerge and most people will gravitate towards this. At this point rider/driver skill comes into it.

This is where karting gets tricky - it has always been a driver's championship. The AKA probably has the same ideals as Motorcycling Australia; to produce the worlds next Aussie F1 champion. Now, club racing is where the wheat is sorted from the chaff, and a national series like AFXSBK is where the wheat get sorted. Like all motorsports organisations, everyone has a view on how it should be done, and lots of folks are put off by the high costs and/or logistics.

From my feeble understanding, the AKA oversees club racing, and clubs own the tracks. They have the power to veto any use of the track, and any competition that isn't AKA sanctioned is basically never going to happen. It's not so rigid over here in the West, as the same circuits can be hired for competitions, as long as a sanctioning body complete with insurance is overseeing the hire.

So the AEVA has a role to play here: We need to come up with a few kart designs that would satisfy the AKA. This includes:

1. lowest cost practical
2. availability of parts and service
3. lots of safety features
4. parity by means of motor/controller/battery
5. parity by means of weight control

So I say members around the country should get busy and start building some karts. Make sure you start with an AKA approved chassis and try to get the weight under some officially recognised figure (80 kg - 100 kg). We'll put them through their paces (say, at an AGM?) and over the course of the next two years, we can make a date with the AKA. I would say go for an off-the-shelf 8 kW continuous AC motor and a reliable controller, and try to limit the battery weight by going for some decent quality lithium ion packs, built to a specific conformation, voltage and capacity.

Now as I said, I know sweet FA about karting and the competition, but if you go to the AKA with a complete plan and some well designed machines, they can be satisfied that there will be parity and the karts will be safe.

ICE karts today are almost exactly the same as they were 20 years ago. EV karts will be different each year for the next 5 years...
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Post by Kieran » Tue, 02 Sep 2014, 03:46

Interesting discussion about electric karts on Kartbook.net:

http://www.kartbook.net/forum/topics/sh ... 1#comments

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Post by roddilkes » Mon, 08 Sep 2014, 01:52

Maybe we can practically start with an E-kart Challenge at next years Perth Electrikhana?

For safety it could be done as an autokhana type event around a cone track, one kart at a time.

Having a standard chassis and very low COG E-karts would actually be very safe.
Last edited by roddilkes on Sun, 07 Sep 2014, 15:53, edited 1 time in total.

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