This Instructable provides an overview of the design and construction of a small electric go-kart or microkart with brushless motors, lithium batteries, independent suspension and a composite deck chassis, built from new components for under $1500. By keeping the design as light as possible, this microkart maximises performance from 6.5hp and its tiny size exaggerates the 40mph top speed.

SKIP TO BUILD STEP 1 - DRIVE TRAIN or continue reading below for more background info about the project.

The Goal

My overall goal was to produce an electric go kart for under $1500 that showcases current motor and battery technology, is suited to on or off road use, great to drive and challenges a few of the standard approaches to kart design along the way.


Some friends are building electric gokarts by taking a sprint kart (fixed gear racing gokart) and replacing the 2 stroke engine with an electric drive train. This is a quick way to make an electric kart, but unless you already have a racing kart you need to first buy a kart which would blow my price goal. I also wanted to further develop the go kart concept in a few other areas including size, chassis, suspension and independently driven wheels.

Size - to keep weight as low as possible, provide greater options for racing in carparks and indoors and make for easy transport in the boot of a car rather than a trailer, this design miniaturises the already miniature, hence the name microkart. This will extract maximum performance from the small electric drivetrain.

Chassis - structurally racing gokarts are flexible enough to lift or at least reduce the pressure on the inside rear wheel when cornering to counter the effect of a solid rear axel. In this design the rear wheels are driven independently with a motor for each wheel so the chassis will not need to flex for cornering and all four wheels can remain on the road. In addition the electrics are mounted inside the chassis instead of on top for protection and a cleaner look.

Suspension - go karts don't usually have suspension which is fine on a smooth kart track, parking lot or in a warehouse, but to find more places to drive it, improve performance and to provide a smoother ride off road, the microkart is designed with suspension. While it does appear to go against one of the principals of the go-kart which is keeping the design as simple as possible, the challenge is to do it cheaply and simply using easily available components.

Independent drive - ultimately I want to produce a 4wd gokart to maximise acceleration on and off road with each wheel independently powered by its own electric motor. To reduce costs and complexity (avoiding CV/universal joints at the front) I will be driving the rear wheels. Independent drive should extract more grip than a solid axel as well as saving the weight of the axel. It also opens opportunities for the future for developing a traction control system.

So on with the build....

Step 1: Motors

One third of the gokart budget, $500 was allocated for the motors and controllers. Higher power motors designed for electric bike use were chosen as providing the optimum combination of power, price and packaging. Two 2000W or 3hp brushless electric motors from Cyclone Motor were purchased online for $159USD each and two brushless electric motor controllers from Golden Motor for $95 each. The motors included a 7 tooth sprocket for standard bike chain. A little over the $500 budget (particularly as the prices don't include delivery costs) but well priced considering the cost was less than $100 per hp.

Getting the power to the rear wheels uses a standard bike chain driving a recycled bike sprocket on each rear wheel. See the step on wheels for more information on mounting bike sprockets on the rear wheel hubs.

Electric Motor Source Guide

There are three main groups of electric motors that are practical options for a go kart.

1. Radio control plane or car brushless motors.

The RC community were great innovators in making their own high power small electric brushless motors for RC aircraft and now there is a huge range of options of ready made motors and controllers. They provide the highest power to weight ratio electric motors available and are very cost competitive, but they are not the most durable, are typically very high revving thus need higher gear ratios for karts, need to be de-rated for use in go-karts to avoid overheating and they are not well suited to start stop or slow speed operation. Hobby king is a good starting point to find a high power RC brushless motor. Instructables user Teamtestbot has a good primer on using RC hobby motors here http://www.instructables.com/id/The-New-and-Improv...

2. Electric bike motors

These are also cheap and readily available, particularly in the 200w to 500w range to suit e-bike regulations. They are provided in kits that are easy to wire up and they are designed for higher torque and slow speed operation. While 200w to 500w would be OK for a kids gokart, there are a few sources of e-bike motors up to around 5kW or 7hp. Cyclone Motor, Golden Motor and Kelly Controls are suppliers of higher power e-bike motors.

This project uses two 2kW or 3hp brushless electric motors from Cyclone Motor. These are ideal size and well priced to suit the project. Cyclone use Kelly controllers for their motors, and while I have found Kelly controllers to be fine on previous projects, Golden Motor cruise controllers have a good range of features at a better price, thus we are using two 48V 50A continuous (100A peak) controllers from Golden motor on this project.

3. Small electric car motors such as etek type motors often sold for small electric car conversions

These are ideal for a go-kart conversion using a larger gokart frame and suppliers such as Motenergy which has replaced Etek motors is a good example. These motors are typically 10hp plus. The disadvantages are that the motor, controller and battery are all going to be more expensive and while they will fit a regular gokart frame well, they could start to be a bit bulky for a microkart. EVPower.com.au supply a 10kW Motoenergy motor for $615 or a 30kW Motenergy for $918 excluding taxes and delivery and a controller is going to cost you a similar amount.

There are a few other sources such as old forklift motors, industrial starter motors but these tend to be hit and miss to source, and can be heavy and / or may not be suited to continuous use in a gokart.

<p>Might i just ask a question? On the batteries step your using a pcm to control the batteries right. But I cant find the pcm with 16 resistors instead of just 8 or did you add the resistors yourself?</p>
No it's using a brushless motor with a brushless motor controller. The controller uses mosfet transistors to turn power on and off to coils in the motor and varies frequency to control speed. I have also used a PWM ( pulse width modulation) controller in previous projects which also uses mosfets to rapidly turn power on and off. The proportion of time the power is on versus off controls speed which avoids the losses associated with resistors
<p>mm I understand... I may be able to build a relay cause i dont want to buy mosfests but thanks ;D</p>
<p>This looks like a very interesting project that I would like to build. However, I don't really understand how the suspension system works. Could someone explain this to me?</p>
<p>Are you familiar with double wishbone suspension and trailing arm suspension? The front is double wishbone see <a href="http://en.wikipedia.org/wiki/Double_wishbone_suspension" rel="nofollow">http://en.wikipedia.org/wiki/Double_wishbone_suspe...</a></p><p>The rear has a trailing arm for longitudinal location of the wheel see <a href="http://en.wikipedia.org/wiki/Trailing_arm" rel="nofollow">http://en.wikipedia.org/wiki/Trailing_arm </a> and double lateral links for the transverse location. The front pivot on the trailing link is not stiff enough to provide lateral restraint of the wheel so it does not act as a full trailing arm as explained in the above link. The transverse links are like a double wishbone in the way they locate the wheel but they are not an A shape, just a single linkage with a ball joint each end so they do not restrain the wheel longitudinally only laterally. Also dug up an early sketch when was developing the idea that may help understand how the rear works.</p><p>Does this help at all?</p><p></p>
<p>Ok now I understand the structure, but where do the rubber stoppers go?</p><p>Thanks for your help</p>
<p>Rubber stoppers go between the bottom linkage and the chassis. The plan has always been to use mountain bike spring / shock units with a rocker from the top linkage and this will give better wheel control and greater travel but the rubber stoppers have been a great solution for smoother tracks as they are very simple, cheap, easily adjustable contribute to a clean look.</p>
<p>Here is the sketch.</p>
<p>How much distance can you get on the charge? </p><p>P.s Awesome project ;)</p>
<p>very impressive!</p>
<p>re: Suspension, Skis make pretty good transverse leaf springs. You can use the portion of the ski which gives you the desired spring rate. You would cut the part you're going to use off each ski and lay them over the UCAs and fasten them to the chassis. You can even replace the upper arms with them like I did on my kid's power wheel. I reccoment cross country skis as they're pretty much the same width throughout the length and are made of fiberglass = super light and strong. </p>
Thanks great idea sounds perfect. Just need to work out where to find skis. Nearest snow to us is 3000km away.
<p>Thrift stores are a good option to consider. The ones in my area regularly have ski's and other winter sporting items.</p>
<p>Got an amp meter on the kart today and it was only running at about 40Amps max, so was able to increase the power by about 50% by adjusting the settings on the controller program. Kart was noticeably quicker and was getting wheel spin on corners and bumps on the gravel driveway. The young fella was having great fun for a couple of minutes until one of the rear wheels came off. The garden trolley wheels just weren't up to over 3kW and the rim sheared off the hub. </p>
<p>I enjoyed this. Thanks!</p>
The headways are much bigger capacity, 15ah versus 2.6ah for the 18650's but at a tenth of the price per cell, the 18650's are cheaper per Ah. The challenge with the 18650's is you need 5 sets of them in parallel for a similar capacity and also the cheap ones typically do not have high discharge rates. Maybe there is a need for an instruct able on building 18650 battery packs. <br>Regards Wayne
<p>it looks unfit for youth .. suitable for children </p>
<p>good job forgot to say</p>
<p>Would be interested to see info on range and weight limitations (or even suggestions on how you would calculate that for this)? Would be a great base for a small art car. </p>
<p>Video planned for this weekend. </p><p>Also no bind in rear suspension. Can place the kart on a stand and rear suspension moves freely with springs removed. </p><p>Wayne</p>
<p>Good Job, <a href="http://www.instructables.com/member/Ganhaar/" rel="nofollow">Ganhaar</a>!</p><p>Interesting project.</p><p>Only one advise -- DO NOT locate Li batteries under the seat. They may flame up or even explode. Consider another location for the battery pack far away from a driver.</p><p>Good driving ;)</p>
<p>Thanks all for the support and good feedback. </p><p>Also note that headway cells are lithium iron phosphate which is much safer / not prone to explosion like lithium polymer and with a battery management system and batteries enclosed in a chassis box, do not need to be concerned about them under the seat. </p>
<p>Thank you for sharing. I have voted for you. Good luck with the contests.</p>
<p>looks like the rear suspension might have some bind in it? can you show a video of the motion?</p>
<p>This is a very nice design. If at all possible can you please provide a close-up photo of the rear suspension from several angles: side (to see how you are allowing the rear wheel to move up and down with the chain) and top (to see how the tie rods are attached to the frame and axles). Having built several go karts myself and working on a 6x6 ATV, I am debating adding suspension to my design instead of relying on partially deflated balloon tires for some cushioning.</p>
That's a fantastic design, could you upload a video of it in full<br>Motion.
<p>Wow that is amazing! My son is in love with it :)</p>
<p>wow awesome please upload video .</p>
<p>Hey thanks Honus and JRF.</p><p>I have an old Moulton Bike with full suspension (pre-dates mountain bikes) and Moulton (mini hydrolastic suspension fame) used rubber in combined shear and compression for the bike rear suspension. I'm sure there would be a great solution using Moulton inspiration plus modern elastomers.</p><p>Wayne</p>
<p>Fantastic documentation - thanks for sharing your kart! :D</p>
<p>Very cool project! Looking forward to the updates!</p><p>The biggest problem with rubber bump stops is that once it starts compressing the spring rate goes to infinity very quickly. You could try using an elastomer bump stop instead as they're a bit more progressive and they come in a huge range of sizes.</p>

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