Electric Go Kart (2023)

2023-2020

The Electric Go Kart is a fully electric, single seater go kart with a 3kW (4HP) electric brushless motor and a 1000Wh lithium battery. The go kart has a range of 20 km (12 miles) and can accelerate up to 70 km/h (43 mph). It is designed from scratch and built by hand using simple tools.

The go kart project was done in my home country, Pakistan, where the availability of parts was very limited. Some of the key parts were purchased in the US and taken to Pakistan while others were sourced from the local market. As a result, some of components weren’t ideal for a go kart, but I made it work with whatever I could find.

I built the initial version of the go kart in Dec 2020 but this will be an ongoing project for years to come. I will make incremental changes and improvements to it every time I am back in Pakistan. Follow the updates section to see what are the changes I have made to the initial version.

I will go over the whole design and build process for the go kart. I will highlight all the major milestones in the process and the key learnings from each milestone. I wont be providing a very specific build guide since I had to design it for the specific parts I could find. You are welcome to take inspiration from my design and replicate the concept with whatever parts you can find.

Please forgive the low picture quality of some pictures since I designed the go kart under a tight timeline so I didn’t remember to take pretty pictures at each step.

Background

I have always wanted to have a go kart of my own that I could rip around in and have some fun. Growing up, I never had the opportunity to buy a go kart since they are not available in Pakistan. So when I reached a stage in my maker career where I felt somewhat confident that I could make one myself, I decided to finally take on the project and build one.

I thought about building the kart in the US but I didn’t have a place to store it, a way to transport it or a track to run it on so I decided to build it at my workshop in Pakistan instead. There, I could ride it on the empty streets without any restrictions.

Part Selection

The go kart started off with selecting the power unit. I did a bunch of research to see what was available. The budget for the go kart was very tight since I was funding this from my part time job during undergrad. I was mainly looking at AliExpress for what was cheap but also would have enough power for a go kart.

I didn’t even bother looking for an engine because it just doesn’t have the same appeal as an all electric build does. As an electrical engineer, I think it wouldn’t be right to build an engine powered go kart. I explored a few different option including wheel hub motors but eventually decided on a motor that was designed for a go kart and had good amount of power.

Motor Selection

I selected this motor kit from AliExpress. The option that I selected was the 72v 3000W C package that had the foot throttle pedal. It costs roughly $300 without shipping at the time of writing but it was around $250 when I purchased it. (Inflation is real)

I selected the highest power option in the price range I was targeting. That is because I didn’t want the motor to be running close to its maximum limit as that would shorten its lifespan dramatically. Also, I didn’t know what the weight of the kart would be so I wanted to play it safe and get the most powerful option.

I am adding some reference material here for the motor and controller.

Here are some specs for the motor and controller

Motor

• Motor Type: Brushless High Speed DC Motor
• Rated Voltage: 72VDC
• Rated Power(Watt):3000W
• Rated Current:45A
• Rated Speed: 4900R/M
• Toque: 5.4N.M
• Sprocket: T8F 11T Chainwheel, Fit For T8F Chain

BLDC Controller

• Voltage: 48V-72V
• Protection Voltage: 42V
• Power: 3000W
• Current: 45A
• MOSFET Count: 24
• Phage Degree: 120

Drive Components

I ordered the motor and took it to Pakistan with me. Now, I had to find the remaining components locally. After a bit of searching, I couldn’t find any go kart specific hardware but I was able to find hardware for ATV quad bikes. I knew it wouldn’t be ideal but since I didn’t have another option, I purchased the wheels, drive shaft and brake assembly. I also got the steering knuckle and linkages. The proportions of the parts were not really right for a go kart but they would work.

Parts for the go kart

There were two main non idealities with the parts that I got, one was that the tires were designed for off-road use and the second was that the drive shaft was very short. Neither of these was going to be a show stopper so I continued.

Parts List

Here are some of the notable parts used in this project

1. Brushless Motor Kit 3kW 72v – AliExpress
2. Go Kart Seat – Amazon
3. Go Kart Steering Wheel – Amazon
4. 100A DC Power Meter – Amazon
5. XT-90 Connector – Amazon
6. 8 AWG Silicone Wire – Amazon
7. 50A Circuit Breaker – Amazon
8. Key Switch – Amazon
9. 2 Position Toggle Switch – Amazon
10. 3 Position Toggle Switch – Amazon

Note: I earn a small commission on Amazon purchases made through this post. But rest assured, my recommendations are not influenced by that at all. Any revenue will most likely go straight back into buying some more tools or supplies.

Proof of Concept

I had all the major parts but I still wasn’t sure if this concept would even work. I had no idea if the motor would be powerful enough and if everything would fit together. So I decided to find that out the fastest way possible and build a very crude proof of concept go kart.

The focus was to just make something quick and dirty because if the concept wasn’t going to work, I would want to learn that sooner rather than later. I dug through my discarded materials bin and found some wood and metal scraps I could use.

The main chassis was made using some pieces of lumber I joined together. The flat section of the go kart where the driver, battery and electronics would go was a piece of plywood screwed onto the chassis wood. The steering assembly did require a little bit of metal fabrication but I did that using scrap pieces of bar stock, no caring too much for it to be very accurate. I didn’t have a battery solution at the time so I just wired up some 18v power tool batteries in series and powered it up. I also didn’t have a steering yet so I used a couple of locking jaw pliers.

I don’t have too many pictures of this concept build since I was moving quickly and not thinking too much about documenting each step. I tested the go kart in the limited space I had in the basement and was happy to see that not only did it have enough power to move itself, it was doing that with very minimal throttle input.

I could feel the potential the motor had in it and if built right, the go kart could move around quickly. The concept build had a very crude steering system and everything was very temporary so I didn’t take it out on the road. I learned what I wanted to learn from it and moved onto building a proper go kart.

Build Process

Planning

I started with selecting the material I would use to build the chassis. I wanted something cheap, strong and relatively easy to work with. The natural choice was steel tubing. Circular tubing would be too hard to work with so I chose 1.5×1.5″ square tubing instead. I had gotten a feel for the size of the go kart from the concept build so I planned out the final size and structure of the go kart.

I initially looked into drawing it up in CAD but this was not that type of project. I took some measurements and sketched out the chassis layout on a piece of plywood. The width of the go kart was constrained by the drive shaft. I wanted the length of the go kart to be as small as possible yet still being comfortable for me to use. If it was too long, it would have a very wide turning radius and it also wouldn’t look right.

PlyCAD sketch for the go kart

Fabrication

I got into hardware mode and prepared all my metal fabrication tools for work. Charged up my power tool batteries and we were ready to get started.

Chassis

The chassis was built using angle grinders and a stick welder. This was my first real project using a welder and my welding skills were not very refined but I was determined to make it work and do that best I could. Making the chassis was a fairly quick process as I cut up the square tubing and welded it together according to my complex CAD drawing.

I did try to fabricate the chassis symmetrically and in increments so that I don’t skew it one way or the other. I didn’t want to find out later that the chassis wasn’t square. For each joint, I would place a weld on one side, followed but a weld on the other side. This would allow for equal movement of the material and kept everything straight and at nice right angles.

Steering Mechanism

The hardest part of the build was to figure out the steering system. Any mistake in the steering system could lead to poor performance and unstable running later. There were also a lot of angles to get right. The tools I was using were very basic so I had to extract the maximum precision out of them.

I decided on a negative camber angle of almost 5 degrees. I calculated the size of the structure needed to hold the steering knuckle. I went on to carefully fabricating it, checking my work twice at every step and using all the tools I had to measure the angles.

One tool that I found particularly useful at this step was an angle cube. Its a simple cube that has a gyroscope and tells you the angle. I was able to carefully measure the angle of each part I was bending and welding.

Steering mechanism for the go kart

I used a threaded rod as the steering shaft and didn’t bother with any bearings or bushings for it. I just welded a couple of vertical support pieces and supported the steering rod with those. The steering rods were connected to the shaft with a plate at the end. I did some trial and error to get the right distance from the shaft center to the rod mounting points.

Rear End

The drive shaft was mounted to the chassis using two heavy duty pillow bearing blocks. I had reinforced the mounting point with double tubing as this would have to take most of the weight of the go kart.

The more challenging part was to figure out the mounting for the brake assembly. The brake rotor was fixed in a specific location on the drive shaft with no adjustment so the brake caliper assembly had to be mounted accurately as well. It also had to be secure because this is a critical safety component.

Motor and brake assembly mounted on the go kart

I designed a bracket for the brake caliper and used some washers to position it correctly. The bracket was bolted on the chassis as I wanted this to be removeable for ease of servicing later.

Finishing Up

The chassis was still bare and it needed flat panels where things could be mounted and the driver could sit. I opted for plywood panels since I had them laying around and they were a quick and relatively robust solution.

I couldn’t find a proper seat so I built a support structure for the driver to rest their back on. That would protect them from the drive shaft and the wheels.

I mounted the motor controller and throttle pedal on the floor panels. The brake pedal was mounted on a custom mounting bracket.

For the battery, I chose 6 12v 10Ah lead acid batteries connected in series. This is all I could find in a timely manner so I went with it. I made a wooden housing to contain all the batteries.

I built a F1 style plywood steering wheel and mounted it on the steering shaft with a bracket. I welded this on since the torque was too much for the nuts to resists and it kept coming loose.

I also built a mini control panel that had the power key and drive controls like speed mode, cruise control and reverse.

With that, the first version of the go kart was complete. Note that I built the entire go kart up till this point in 10 days so a lot of things were rushed. If I had more time, I would have done them more properly but I just wanted to finish the build so that I can drive around and have some fun as well.

Testing

Posing in between speed runs up and down the street

In the next few days, I drove the go kart around a lot. I went uphill, downhill and around corners. I also drove on a variety of surfaces. I tested the brakes out in a slow and sudden braking scenario. I was enjoying the go kart a lot but I was also trying to expose weaknesses in my design that I could improve on. And there was a lot that I learned.

Key Learnings

• The battery wasn’t up to the task. There was too much voltage sag and it couldn’t deliver the current required for very long. I got stranded once and had to push the kart a mile back home. The kart needed a better power solution.
• The steering was very stiff and didn’t have end points so the wheels would rub against the chassis and make turning very difficult.
• The seat and battery position didn’t make for a comfortable driving position.
• The wheels were not aligned and balanced very well so the kart would get hard to control at higher speeds.

My vacation time in Pakistan had ended and I headed back to the US. I left the go kart in the state it was in with the hopes that I will continue working on it in the future.

Updates

Here I will detail the updates I have made to the go kart over the years. Keep checking back to see what is the latest on the go kart.

Jan 2023

The next opportunity I got to work on the go kart was January of 2023. I had a few upgrades in mind and I purchased some parts from the US that I could take to Pakistan for the go kart.

The go kart was stored in the basement hence it started to develop varying levels of rust on the chassis which I wanted to deal with. I also wanted to rebuild some parts of it including the floor and control panel. So I started by completely breaking down the go kart.

I grinded off the back support panel I had built as a make shift seat and replaced it with a bracket for this seat. I added a limiting plate on the steering to have defined end points and welded on the bracket for this steering wheel. I then sanded down the whole chassis to remove all the rust and gave it a nice coat of black paint.

It is starting to look so much better already. Next I built a new floor using left over panels from my bedroom flooring. They have an aesthetic finish and the way they interlock together allowed me to build it in pieces and put it together to look like one continuous piece.

I mounted all the remaining components including the new lithium polymer battery back. This was built by a local supplier that uses recycled cells. I rebuilt the control panel, this time adding this power meter that monitors the voltage, current and power used. That is a good way to gauge the battery life left. I also upgraded the switches and used a much higher quality key lock. The control panel construction wasn’t exactly what I wanted but without a laser cutter or 3D printer, my options were pretty limited.

Finally, I mounted the seat, tidied up the wiring and we were ready to go.

Go kart finished up and ready to go

With that, this round of upgrades was done and I was ready to enjoy the go kart for the little time I had left. And it was pure joy.

Key Learnings

• The new battery made it go faster and last longer. I was also able to estimate how much range I had left, thanks to the power meter.
• High speed stability was still an issue.
• Steering was still pretty stiff and the maximum steering angle was limited which made the turning radius quiet large.

Future Work

This is a running list of all the ideas I have for things I want to add or improve on the go kart. Hopefully, overtime, things from this list will move into the update section as I continue working on the go kart.

• Add a data logging module that records telemetry (location, speed, temperature, battery voltage, current etc.) and upload it to the cloud when internet connection becomes available.
• Add a digital display that shows important vehicle telemetry and a virtual gauge cluster.
• Modify the chassis to allow for a sharper steering angle.
• Build a custom steering rack and pinion for higher precision and lower torque steering input.
• Switch to road wheels and get all the motion components aligned and balanced for better stability.

Conclusion

Thank you for reading through my go kart design and build process. I hope you were able to take some inspiration for your own projects. While it might be discouraging to not have access to high quality tools and parts, take it on as a challenge and do the best job you can. It will train you to become a better problem solver and a better maker.