Step 5: Eli-Kart: Electronics

At the core of the electronics is the motor controller. For Eli-Kart I used a Kelly controller, the KBS48121 with the high speed option. The high speed option is expensive but allows for the use of higher speed motors. Sadly this turned out to be a waste for me since my custom motor spins extremely slowly, so I would recommend using a slower motor and saving your money unless you are going for extremely high performance.

Anyways, Kelly controllers have connectors for pretty much anything you would ever need. Reverse, regenerative braking, even brake lights and a beeping sound. I neglected to use the connectors it comes with and soldered my own .1" headers onto the connections I would use. I would recommend soldering the connections once you know everything works, but tape works well for making sure they don't fall out until then.

One downside to this type of controller is that you need to have sensors on your motor to allow the controller to detect its position. Read into the custom motor section if you want to know more about this, but you'll essentially need to either take apart your motor and put in sensors or use digital fabrication to make a sensor mounting board.  The alternative to this is to use a sensorless controller. These will require a little push-off to prevent your controller from exploding on the inside, so keep that in mind when designing your vehicle.  You can pick up cheap sensorless controllers from Ebay.  They are surprisingly legit as proved by Charles, though I would recommend this one.

At the bottom of the food chain are brushed DC controllers, which can be cheaper and easy to use.  Kelly Controls also sells DC controllers, or you can go with scooter parts. This might be a good option if you want to save money and time but don't want to go sensorless, or if you already have brushed motor lying around.

Batteries are the I made my own custom battery pack out of A123 26650 cells, combining 12 in series and 3 in parallel for a 39.6V 7.5Ah pack. Unless you have your own personal stock of batteries, you'll need to buy some. You can find batteries online at places such as All-Battery, Amazon, and HobbyKing. I would avoid using lead-acid batteries due to their low discharge rate and poor lifespan, but be careful if you go with Lithium Polymer batteries such as the HobbyKing pack I linked. You will also need a battery charger.  I have a 0-40V charger with balancing and a generic power supply, but if you know exactly what you will be charging you can get cheaper solutions such as this or simply a power supply.

You'll need a soldering iron to make the wiring connections, and thick wire for the main power connections as well as thin wire for the signal connections.  Feel free to color code your wires, and label them if at all possible to avoid potential electrical headaches. Don't forget connectors as well: T-style "deans" connectors, bullet connectors, or XT-60 connectors should be all you need (just don't plug or solder anything in backwards).  Digikey is also a good supplier for anything electronics related if you're not ordering parts from HobbyKing since they have free, faster shipping.

Basically, you get what you pay for when it comes to electronics. Brushless systems with a quality controller and Li-Ion batteries will give you the most reliability and best performance, but will run you around $100 per component.  Lead acid, brushed components are probably around half that, but the motors aren't any cheaper and offer much less power.
<p>I just started to be interested in engineering and I wanted to know how long it took you to finish and the estimated budget for the entire Electric Go Kart . Thank You very much for the post and hope you answer me!!!</p>
The kart looks great! How stable is it cornering at speed, with three wheels and a relatively high center of gravity? Also, how does the performance of your custom motor compare to the aircraft (turnigy?) motor?
Thanks! Stability is an issue, and I would recommend going with either a lower center of gravity or 4 wheels instead of neglecting both. One wheel drive is very convenient though so it's a tradeoff. With no passenger, its not too bad if you keep your weight over the front wheels, but Eli-Kart is really not made for lateral g's. <br> <br>Mostly because the motor is much bigger (5&quot; diameter and 5&quot; long compared to probably 2.5&quot; by 2.5&quot;) it produces about 6 times as much torque per amp. Given that, it spins 6 times slower. I'm only running it at the same voltage (40V), but since it spins slower I can probably run the motor at a much higher voltage (I'm hoping for around 100V or so). Again, I haven't pushed it but it should be able to sustain about twice the current of the hobby motor. Together that's probably at least 4x the power output if you have the right batteries/controller.
Good kart. I'm only 13 and I'm about to finish my first kart and post an Instructable about how I built it. Mine will hopefully have a faster gas motor. I will scrounge the junkyard for one. The wheels will be a larger set of off road tires in rear of the kart. The front tires will be smaller off roads too. How much thrust does your motor deliver to propel it? Mine is not finished yet.
Sorry for the simple question, but how fast does it go? Very cool!
Just uploaded a video of Eli-Kart being tested! The steering was a bit loose so he didn't want to hit top speed, but you can see the acceleration pretty well. <br> <br>http://youtu.be/kAGa7U7URYo
It goes about 20mph tops and has good acceleration with the hobby motor. I should make a drag race video and add it to the end :)
What if you made it a one seater with a much bigger rear wheel. Then lowered the chassis for better stability. Basically and electric Can-Am spidyr. Then with the bigger wheel for better traction and a lower center of gravity for better handling. It would be so cool.
I like your idea.. A larger 20&quot; ? wheel will be much more stable since the center of gravity at this wheel will be well below a small wheel, and now will be much more stable and the cornering is much better. Of course the heavy parts must be mounted as low as possible, like a Can AM car. <br>Added bonus of your larger wheel is a much smother ride. A 20&quot; H D bike tire/wheel should be great , dont you think? It seems you can use the stock gears too ,cheap and good too? A 55 or 65 chain wheel can be bolted up easily th th e last large gear if you wanted to drop the gear ratio . <br>I made one of these 3 wheelers many years ago and used a wide front track and a 24&quot;? bicycle wheel at the rear . . I did use rubber mounted smaller wheels as out riggers on the rear, but rairly needed or used them . <br>I ues 3 battries and manually swithed the voltage from all batts in parellel for hills or starting and then 2 in parellel and one series ect till all were in series for high speed and level ground. A switchis easy to make use silver dimes for contacts is great.
I think it looks like you have made a pretty awesome and fun kart. For stability you could simply add some casters to the back corners. I think either swivel casters or no swivel casters would work. The non swivel casters would require a little closer alignment, but with your skills you could get it done easily. You get the simplicity of the single wheel drive and the stability of having wheels at all four corners.
LOL there goes my kids electric battery scooter. <br>Cut up the chassis rear end for the motor and wheel and battery, only need a second front wheel and platform. <br>Steering column, handle bars already there, speed control and brakes too. <br>Could put free wheeling caster wheels each side of platform rear, cheap stability. <br>Great idea for the younger kids - GOOD job.
Thanks! Kids seem to love it when they see me driving around.

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