First off, if you like my instructable, please go ahead and like it and vote it to win the Make It Move Contest!! I would really appreciate that, thanks!!!
Note: I do have this instructables page created into a PDF that I converted and modified for readability. If you need or would prefer a PDF version please let me know by messaging me. I would be open to share that with you.
This was one of my very first completed projects. I have been very interested in physics and electric bikes, go karts, and cars ever since I was in elementary school. The summer leading into junior year opened up to accommodate this lengthy project. Besides from the fun of building and driving this go kart, the experience and knowledge that I gained are priceless. The process of building and converting this go kart from gas powered to electric powered not only happened to be my passion, but also helped me to learn and grow as a student. Enough of my background, let's start this project!
Why should you build an electric go kart??? (Need a motivation?)
If you are reading this, I can probably assume that you have some sort of interest in electric powered systems, physics, go karts, dirt bikes, or anything that is FUN!! If you have a passion for building things this project might be the one. This build will ensure you to get your hands on a welder, drills, grinder, and jigsaws. Nothing can bring more joy to you than building something yourself. So, if you happen to have time on your hands and if you are passionate, ahead and read on. If you are in to learn something new in the physics or mechanics field, this may also be a bet. You will for sure have to do some research on circuits, resistors, fuses, and much more!! And finally, if you're looking to just ride a go kart but your parents do not want to buy you a brand new one, this may also be suitable. Tell them that you want to build a go kart and learn something. Surely they will accept that, and hey, maybe at the end you might end up having a new predilection for building things! At the end of the day, this project will entertain you throughout the journey. Even though you might not realize, as I didn't, you will learn many new things: how to use power tools, how to think creatively when at a standstill, plan before implementation, etc... Overall, many of these skills may end up being useful for your future career, and most importantly, the rest of your life!
Step 1: How to Get Started
- Make time for this project: Since I dived straight into this project I didn't have much prior knowledge or experience to utilize for this project. Thus, I spent a solid 3 months to complete it. And, within those 3 months, I spent around 4 hours a day.
- Be prepared to invest into this project: By invest, I mean around $3,000. Now don't let that frighten you. Before I started this project, I had nothing in my hands. Seriously... I didn't even have some screwdrivers. So, if you have a toolbox of some kind you already ensure that you will spend less money. And obviously, if you plan on building a go kart with lower performance parts, you will be cutting down this bill significantly (See the bottom of this page for my personal Expenditures Sheet). I think that because I started this project without any idea, I spent a lot of money on unnecessary things like a welder which I barely used. After everything, I think that about $1000 would be a good estimate of the real price of this project.
- Plan, research, plan, research: For me, the majority of this project was dedicated to researching and planning out how I would put together this kart (placement of batteries, motor, etc.). Don't be frustrated if it's been one month and you haven't started to build the go kart. You should plan out the project properly rather than spending loads of money on something you didn't account for. Then, you will be wasting your money and time. Overall, I spent around 200+ hours in total for this project.
- Think of something unique: After you read this Instructable page, please remember that this just serves as a model for a different go kart that you could build. For example, instead of having a motor that accepts a max current of 300 amps (mine), you could get a motor that could make use of 400 amps (CRAZY FAST!!). At the end the idea is yours.
- Final Goal: Before you start, you want to have an idea of what you want to end up with. Do you want a go kart for offroad? If yes, then you need to get a roll cage with an offroad chassis. Do you want your kart to have a reverse gear? If yes, you need a reverse contactor. You get the idea. Make sure to note down what you want your go kart to look like. That way, you have something to work towards. Think about your budget, how fast you want to go, etc.
Step 2: Obtain the Base Frame
When I first got my frame, it was a racing chassis that was used previously for gasoline engines. Before building, make sure to clean up the frame of any corrosion and take out the gasoline components that won't be used in the electric conversion. There are many other frame options from off-road chassis to ones with roll cages. It all depends on your build and final goal.
Step 3: Choosing the Electric System Based on Go Kart Features
This step was completed after about a month of research. This was the hardest part for me because I did not know what I needed for an electric system to put on a go kart. It is also impossible to tell you how to make an electrical system in one page. Therefore, I have posted sources and pages that were of great help to me. Those resources taught me more about these electrical components and helped me in applying that knowledge to construct my own electric drivetrain.
Brushless or brushed system: I created a chart to compare both of these systems in order to pick. I picked a brushed system in this case for cost reasons. Brushless motors have higher performance and energy efficiency. Although, they cost more and you end up loosing power and speed compared to spending the same amount of money on a brushed motor (which is what I did).
Lithium or Lead Acid Batteries: This was a clear pick for me, again, because of the cost margin between the two. I chose lead acid batteries. Lithium batteries are great but also on the higher end of the financial spectrum for batteries. Lithium ion batteries are known for high discharge rate, which translates to good acceleration when talking about go karts. Lead acid batteries, on the other hand, are cost-effective, but have a battery life nearly half of that of lithium ion batteries.
Controller: The name says it all. The controller controls the amount of current it sends to the motor based on the foot throttle input, which is connected to the controller. I wanted a controller that was fairly easy to program and put to use. The controller also had to be compatible with the motor and battery voltages.
Step 4: Get the Electric Components of the Kart
A basic electric powertrain is composed of batteries, a speed controller, and a motor. There are many other safety features and components to enhance efficiency that I have incorporated in my project: solenoids, fuses, diodes, precharge resistors, etc. The system I picked out is one that consists of a 48 volt lead acid battery pack. I chose not to pursue with lithium-ion cells merely based off of the cost of a good lithium pack. In my 48 volt system I have 4 individual 12 volt Interstate batteries. I picked out an Alltrax brushed motor controller which was fairly simple to program and didn't need much programming (almost ready to run as stock). I know that other controllers from Curtis and Sabvoton require a little more programming, which could be a possibility if it interests you. Finally, the motor. No matter how good the batteries and controller are, if the motor cannot keep up with the current provided by the batteries, you will not be able to get good acceleration from the motor and there is a risk of burning it. I chose a Motenergy motor programmed by the factory for 48VDC with a peak current of 300 amps. Please note: All components must be compatible for the same voltage. I chose 48 volts in my project. Below I have put links to the online stores where I bought the components.
Step 5: Sourcing the Rest of the Parts
Above is a picture of all of my parts laid out on a table. Most of the parts were sourced from EVDrives or Amazon. The customer support at EVDrives proved to be a great help technically and with purchases.
- The fuse, reverse contactor, main contactor, and the throttle box came with the custom kit that I linked in the previous step. The contactors and fuse are sold in 24v, 36v, 48v, based on what system you want to go with.
- The lugs and 4 guage wire were bought here. It is safe to buy 4 guage wire in order to make sure that the wiring can handle high current heat.
- I also have included pictures of the tie downs I used for the battery mounts, fuses, shrink wrap, and terminals for the wiring. All of this was bought form my local HomeDepot for cheap.
Step 6: Gather Tools and Materials to Start Building
Some optional but extremely helpfulpower tools include (hand tools could be used as well):
- MIG Welder
- Angle Grinder
- Corded Drill
- Wire Cimper/Cutter
- U bolts for the frame
- Tie Downs
- Wire terminals
- Wire and cable(4 AWG and some small wire)
- 64 tooth sprocket
- Motor L-bracket
Step 7: Build Battery Mounts
Now it's time to start building! You need to have some way to mount the batteries securely. I used a piece of plywood on either side of the kart and then use tie downs to strap them down. I ran the tie down through some eye hooks on the plywood. A much better way to do it would be by using a metal container and then welding it to the frame directly. Regardless how you do it, try to distribute the weight equally so that you don't lose steering control or grip on the rear wheels. At the end, I painted the plywood red to match the frame color.
Step 8: Bolt Down the Contactors and Throttle
NOTE: The main contactor is the one shaped like a cylinder while the reverse contactor is shaped like a box and has half of it covered with black plastic.
For this particular go kart I had a lot of space on the back of the seat underneath the rear axle. So, I decided to put my contactors and throttle over there. I again used 3/8" plywood and then bolted it down to the pipe frame using some U-bolts. I used U-bolts to secure the plywood. Then, I bolted the reversing and main contactor and throttle in convenient places away from the axle to avoid any moving parts. Before bolting down everything, make sure you have enough wire and cable to wire up all of the components. And for the throttle, I would recommend to place it at a position that is lined up with the gas pedal cable. That way there is no slack or turns when you connect the gas pedal cable to the throttle hand.
Step 9: Wiring Everything Together
In order to create a 48 volt battery pack I connected the 4 - 12 volt batteries in a series connection. This means the positive end of one battery to the negative end of another and go on until the pack is finished. DO NOT complete the circuit by connecting all of the batteries in a loop, this will create a big explosion. Connect the contactors, fuses, motor, and controller as part of the bigger circuit that will be able to handle 300 amps. The smaller circuit will consist of the key switch and the forward/reverse rocker switch that connect to the Alltrax controller. Use good, strong metallic wire terminals to ensure high conductivity. Crimp the wires firmly to avoid loose connections and corrosion in the lugs and wire ends. I have attached a wiring diagram that replicates the design and layout of the wires and cable that I used to connect all of my electrical components. Remember, many of these components are not necessary such as the fuse and reverse rocker switch... they are just additional features on the go kart that make it safer to use, i.e. in any case of a short circuit to the frame, the fuse can stop a surge of current from passing that is over 300 amps. CHECK ALL CONNECTIONS BEFORE TURNING ANYTHING ON. Electricity is dangerous so make sure that everything is properly connected and that there are no possibilities for a short circuit. It may be worthwhile to get someone knowledgeable on electric circuitry to help check it out for you.
Step 10: Mechanical Work
Finally, once the electric components have been put together, you just need to finish putting together the kart. In order to mount the motor, I avoided a costly purchase of a motor mount. Instead, I bought a cheap L-bracket that was machined to the motor specs. It was an aluminum bracket that a local machining shop happened to have at disposal. For many of the parts to build this go kart, there may be people or shops that are willing to help you out with them. Since the motor bracket secured with U-bolts that could slide along the rails , I was able to adjust chain tension (this is very convenient and ends up saving a lot of time). I used a #35 chain and my gear ratio (rear to drive) was about 3:1, which ended out being perfect in terms of the balance between torque and top end. Specifically, I believe my rear sprocket ended up being 64 tooth and my drive sprocket is 23 tooth.
1. Tighten the motor plate to the frame so that it will not move when in motion.
2. Align the rear sprocket with the drive sprocket
3. Put the chain over and use the chain link to connect the two ends of the chain
4. Ensure that the chain has no more slack than 1/2" up and down.
NOTE: When you connect the chain, make sure to position the master link such that the open end is facing the clockwise direction. I have included a picture of this.
Click on images to see details.
Step 11: We're Done! Let's Ride!
Before you take the kart out to ride:
• Put the wheels on and make sure that they are not worn out!
• Make sure that the wiring is securely strapped to the frame (preferably by zipties or locks/hooks).
• Check to make sure there are no possibilities for a short in your electric circuit... that would be really bad and your go kart would be destroyed.
• Take the time to cross check everything. Better to be safe the first time, don't rush into it. Once everything is done, go ahead and start drifting it out!!
Hopefully you learned something from the project. More than the product, you probably will have appreciated the experience and pitfalls during the build. Be proud of yourself, good job!! I have included a video of my kart in motion with me giving a thorough explanation live time (please give it a like and comment). Again, this page didn't cover a majority of electric go kart and the technical side. There's just so much to learn. I would recommend looking towards past go kart projects from other people in case if you need more references to start from. And again, please feel free to contact me for any questions (technical or just about my creation) about my kart or a build of your own.
Step 12: Additional Info...
Some resources I used that helped me throughout the way:
1. Endless Sphere (many projects and info regarding vehicle projects
2. Battery University (everything batteries)
3. DIYGoKarts (everything go-kart related)
F.Y.I. The Alltrax controller comes pre-programmed to the setting that you order it with. So, it is not necessary to program it. But, if you want to make it customizable, the controller is programmable with a free Windows application. The program allows you to set the max current to the motor, the torque and speed curves, etc. This came out to be especially useful after the first time I took my go kart for a ride. The batteries started getting pretty hot to the point that one of the terminals melted. This meant that I was flooring the gas pedal too much. So, I adjusted this by limiting the controller to 200 amps. This was extremely useful because now I have no problems with the batteries overheating!