Sunday, October 14, 2012

Installing brake switch and wiring light and fans

The controller came with an input for a brake switch. This activates the brake lights (which I didn't install) and cuts power to the motor during breaking. This is important so that the motor doesn't get damaged by an inexperienced rider who presses both pedals at the same time. The video shows how it works. The switch "Mechanical Rear Stoplight Switch | 2400115" was ordered from J&P cycles for $6.99.

The other thing I wanted to discuss was how to wire a 12 volt light to a 36 volt circuit. One way would be to wire it directly to one of the 12 volt batteries, however, it would have to be switched independently  would require more wiring, and would deplete one of the batteries faster than the others. What I decided to do is as follows: I wired a 12 volt fan and a 24 volt fan in series to the power indicator wires from the controller. I then wired the light in paralell to the 12 volt fan. I checked the voltage with a voltmeter across the 12 volt fan and it was slightly less than 12 volts. The light works fine. Here is the circuit diagram:

The go kart works really well. The fans keep the controller and motor cool. The batteries seem to last pretty long. The kart handles well. It has reached a top speed of 20 mph on the street.

The only minor issue I have noticed is that the chain doesn't seem tight enough and it is a bit noisy. I will probably have to use some washers to elevate the motor in order to tension the chain. Alternatively, I could use an idler pulley to tension the chain. Example:

Friday, October 12, 2012

First Run of Electric Go Kart and First Problem, Solutions

Here is a video of the maiden voyage. It worked perfectly for a few minutes before it died!

At first we thought the controller shorted out or the batteries died. When we opened up the engine cover we smelled burning plastic. The problem was that the connectors from the batteries to the controller and from the controller to the motor melted. The odd thing is that these connectors came with the controller. I actually thought that they cheaped out on the wires. I went to Home Depot and bought some heavy duty connectors and a crimping tool and we were back in business. When I called TNC Scooters the next day, they told me that sometimes the connectors are not rated for the right amperage. This was a $30 controller, I guess I should be happy it worked at all.

Original Connectors:

Battery/Motor Connectors (2-pin) from TNC Scooters
These melted after 5 minutes of use.

New Connectors:
These are 12-10 gauge (high current) connectors from Home Depot
These worked perfectly, no more problems.

Shortly after I installed the Dorman LED indicator light, it blew out. I quickly diagnosed the problem. The wiring diagram for the controller is as follows:
Wiring Diagram from TNC Scooters
I assumed that the power indicator would be 12 volts since most electronic components such as lights and accessories are 12 volts. I was wrong. The voltage is the same as the supplied voltage from the batteries, 36-39 volts. This is way too much for a 12 volt light. I searched for a 36 volt LED indicator light and could not find one. I ended up buying another 12 volt Dorman indicator light from and used a work-around technique which I will describe later.

After changing the connectors and using the go kart a few more times, I noticed problems with overheating of both the motor and controller. The controller seemed to heat up after a few minutes of use and stayed hot. Airflow over the controller from opening the mailbox door did not help. The motor only seemed to heat up when used at low speeds with high load such as driving around in the grass in circles. If you look on YouTube, you will see examples of overheating MY1020 motors:
On, there is a thread called How to Ice Your Motor which gives great ideas for cooling electric motors. Fetcher and Lessss post some great pictures showing Nidec centrifugal blowers attached to their electric motors. I checked Ebay and found that you can buy these types of fans for about $10 each. When buying Nidec fans, look at the voltage and amperage. Since I have a 36 volt system, I decided to buy one 12 volt fan and one 24 volt fan and string them together in series. Here are the fans I used:

Nidec 24 VDC 0.40 A fan. Link to fan

Actual pictures of Nidec fan:
Nidec Gamma32 Front
Nidec Gamma32 Back

Nidec 12 VDC 0.46 A fan. Link to fan on Ebay.
Nidec Gamma30
Once I had both fans wired to the power indicator connector on the controller and installed them properly, the overheating problem was completely resolved. Both the controller and engine stay cool at all times. The cost is a 15 watt draw on the batteries. This will result in less driving time between charges but I haven't noticed the difference.

Picture of Nidec Gamma32 blower attached to MY1020 motor with a plastic bag directing the airflow through the motor.

Here is a video showing the fan in action:

Sunday, October 7, 2012

Parts and Build Out, Discussion of Motor, Batteries, Controllers, and Gearing

An electric go kart consists of the following:
-Go kart frame with wheels, tires, seat, brakes,& throttle
-DC electric motor
-Electric throttle
-Wires and connectors
-Housing for motor and/or batteries
-Proper gearing / sprocket / chain

Before we get into choosing a motor, controller, and batteries, I would like to introduce a few concepts for those who are unfamiliar with electrical devices.

Electricity: AC and DC
First we need to talk about DC ( direct current) and AC (alternating current). Direct current means there is a constant voltage coming from the source (batteries) and going to the load (motor). Batteries are always DC and therefore, portable electronic devices are almost always DC since they are powered by batteries. AC is used when electricity is transmitted long distances, such as from the power company to your house or throughout your house to power your appliances. In AC, the voltage alternates direction (polarity + and -) 60 times per second. In the US, residential power is 120 VAC that is volts alternating current. If you watched the voltage on a display you would see the voltage go from positive 170 to negative 170 in a sine wave pattern at a frequency of 60 hz. The reason why I said the peak was 170 (approximately) is that the average positive voltage is 120 and the average negative voltage is 120 also, that means at the peak of the wave it will be higher than 120 positive and at the lowest part it will be less than 120 negative. AC voltage is expressed as an average using the root mean square (RMS) function.
The bottom line here is that you don't need to know anything about AC for the purpose of building an electric go kart. You can not use an electric motor designed for AC current in an electric go kart without significant technical modifications that are beyond my expertise. You should only look for DC motors.

Batteries: Volts and AH
The batteries provide DC current and all of the components will use DC electricity. You will see electric motors listed with their voltage and type of electricity for example 36 VDC means 36 volts direct current. Batteries are usually 6 or 12 volts. They differ in the amount of energy they hold. This is usually displayed in AH (amp hours). The more AH, the more power the battery can provide and the longer it can run without being charged. As far as getting the right voltage, you simply need to have enough batteries to add up to the voltage you need. For example if you are using a 36 volt motor you would need three 12 volt batteries or six 6 volt batteries wired in series to add up to the right voltage. The cheapest batteries that can be used for this type of project are sealed lead acid (SLA) type. You could also use marine type batteries that are rated "deep cycle", that means you can use most of the battery's energy without damaging it. An automotive battery would not be appropriate because it would be damaged by discharging it in this application.

Motors: Brushless vs. PM
Regarding electric motors, we have covered voltage and type of current (AC and DC). There are a few more concepts to understand before purchasing one. The type describes the inner workings of the motor. There are two types, permanent magnet and brushless. For a detailed description, see Wikipedia: DC Electric Motor. In summary, brushless motors are lighter, more efficient, last longer, are more expensive, and more complex. PM motors are cheaper and easier to use since the controllers are also simpler. Brushless controllers require feedback sensors to be installed on the motor to relay speed and position information. If you are going to buy a brushless motor, I would recommend you buy the motor and controller together as a package so that all of the sensors and wiring are taken care of. For example see this package at 1500 Watt BMC Brushless Motor and Controller. It is difficult to install the sensors yourself. The simplest and cheapest option is definitely PM.

Motors: Power
How much power do you need? First let's discuss how motors are rated. Horsepower (hp) is most common but you may see watt (w) or kilowatt (kw = 1,000 w) used. One hp is equivalent to 0.75 kw. The hp rating is referring to the output of the motor. You also need to know the current rating along with voltage which tells you the input to the motor. This is important because the controller has to be matched to the motor as far as current and voltage.
As far as choosing between different power levels, consider the following. The higher power level you buy, the more it will cost and the faster it will deplete your batteries, and, obviously, the faster it will drive your go kart. If this is for a child and it is a medium size kart, 500 to 1000 watts should get you to 15 to 20 mph. For an adult and for higher speeds 3 hp (2.2 kw) and up is recommended.

Motors: Duty Cycle
 Another consideration that goes with power is duty cycle. A motor may be able to perform at a high power level for a short amount of time and a much lower level of power continuously. Look for descriptions such as continuous use or intermittent use in the motor description. If it is not specified there are some clues to look for. The most important one is - what is the intended use of the motor? Starter motors and winch motors are clearly for intermittent use. If you run them for more than 10 minutes at full power, they will likely overheat. Pump motors, fork lift motors, and golf cart motors are designed for continuous use. The size of the motor housing and the presence of cooling holes or fans also can tip you off to the ability of the motor to perform at maximum capacity for long periods of time. For example, if you have a 1 kilowatt motor that is the size of a spray paint can with no cooling holes, I guarantee it will overheat in a few minutes. There is no way that that small of a motor in a closed housing can dissipate the heat that is generated. Larger designs with more airflow will be able to sustain high power performance without overheating.

Motors: RPM
Another feature of motors is show fast they spin. This is expressed in RPM (revolutions per minute). Most motors that I have come across spin at about 3,000 rpm. Generally speaking you do not want too high of an RPM since the rotational speed has to be reduced by gearing and it is more difficult to reduce the rotational speed if you are starting with a higher number.

One more item I thought I would cover is why you need a controller. If you have an electric motor and you hook it up to a battery, it will turn on and your car will go. The problem is that you will go full speed and your only option to go slower is to turn it off. You want to have something to modulate the amount of energy (current) going to your motor so that you can have control over how fast you want to go. In a car, you use an accelerator. In a go kart we call it a throttle. The throttle signals the controller as to how much current to send to the motor. The other important reason for the controller is to protect the motor from too much current which can cause damage. If your motor is rated for 40 amps of current, you want a controller to limit the current to 40. If your motor draws 60 amps from your batteries, it will quickly overheat and burn out. Finally, many controllers will protect your batteries by shutting off when the battery gets dangerously low in charge. Batteries that are run on empty can be damaged. Some controllers have special features such as half speed reverse, and connection for brake lights. Some controllers are programmable, the more you spend, the more features you get.

Motors: Choosing from available options, DC PM 36 & 48 V
Since this is for a child, I figured I want about 1-3 horsepower motor. It seems the best motors for a go kart are either the 3 hp golf cart motors or the 10 hp Mars Etek style motors originally made by Briggs and Stratton. See below for pics.

Both of these options are quite expensive ($600-1000) and offer more power than we need. The golf cart motor also needs to be modified since it is meant for a spindle shaft from the golf cart transmission and does not have a drive shaft to attach a sprocket to. Another option is an electric scooter or bike motor.
Chosen Motor: MY1020
I found that TNC Scooters has the best selection of motors, controllers, and accessories for the power level that I am looking for. They have a 1000 watt 36 volt motor for about $100. It is called the MY1020. It is a very popular option for scooters and e-bikes and comes in different power and voltage levels.

Go Kart Frame
Before buying the motor and electronics, I had to decide on a frame. I found a really nice new option at Go Karts USA. They sell the Road Rocket GoKart Kit with 5" nylon wheels for $522.00. It has a padded bucket seat, 1" live axle, 6" drum brake, 11.6" knobby tires, steering wheel and steering hardware, sprocket and hub, #35 chain, brake hardware, and throttle hardware. It comes without an engine which is perfect for an electric conversion project.
In retrospect, this might have been a better option. It looks like a really nice frame and has all new hardware.

Instead of buying a kit or new frame and components, I ended up buying a used go kart and refurbishing it with the help of my brother and his friends. Luckily he works for a lawn service company and has all the tools needed to do the job since they are used to repairing their lawnmowers and vehicles there.

My buddy Joe picked up the donor go kart for me for $150. The frame was in decent shape. The tires were dry rotted and one was flat. The steering wheel was rusted and wrapped with tape. The gas engine wouldn't start. The seat was really dirty and ugly. I lost the original picture. We brought it to the shop, sanded the rust, removed the wheels and tires, engine, and the seat upholstery and proceeded to prime and paint it. We also moved the gas and brake pedal back about 4" so that my son would be able to operate them. Here is one of the earlier pics:
It was originally blue, we decided to go with red. I bought Rust-Oleum 7830730 8-Ounce Rust Reformer from Amazon for $9.63 to remove the rust. It sorta worked but is not a substitute for sanding. I found that the wire brush attachment for the drill worked best. We used a few cans of Rust-Oleum Professional 15 oz. Aerosol Primer for $5.58 from Home Depot in addition to Dupli-Color DE1645 Ruby Red engine Spray Paint which we got from a local auto parts store for $5 per can. We originally painted the wheels silver metallic but it didn't come out good so we went with black. One tip, always buy twice as much paint as you think you might use. This project took 2 cans of primer, 3 cans of red paint, and 1 can of black paint.

We used a metal plate which was placed over the original motor mount and secured into place with u bolts and other bolts. This was designed to be a platform for the batteries and the motor.

Chosen Batteries: 12V 18 AH SLA
As far as the voltage, there are a few options. The 1000 watt motor can be ordered in 36 and 48 volt form. I figured I would rather use three batteries than four for simplicity so that is what we decided. As far as batteries, I ordered 3 Rhino SLA 12V 18 Ah Battery from Amazon for $37.99 each as of 10/7/12, price may have dropped since then. I figured that I always could add another battery to make it a 48 volt system in the future. In that case I could over-volt the 36 V motor and change the controller.

Seat Refurbish
The seat was stripped and the frame repainted. I bought upholstery stuffing from Michaels for about $20 and some vinyl covering for another $20 from a local fabric store. I used a stapler to attach the vinyl to the wood pieces which was then screwed back onto the frame which I painted black.

Itemized order from TNC Scooters:
1000W Motor - 36 Volts with Mounting Bracket (Style: MY1020-B)MOT-106165$92.001$92.00
Metal Foot Pedal Throttle Cable (Hall Effect)THR-101124$18.501$18.50
36 Volt Controller (Model: CT-660B9)CTL-101205$30.001$30.00
40 Amp DC Circuit BreakerCBK-101266$7.001$7.00
36 Volt - 3.0 Amp XLR Battery Charger FAN COOLEDCHG-101142$40.001$40.00
XLR Charging Port (3 Pin)CHG-101245$3.501$3.50
2 Pin Modular ConnectorCON-102300$0.506$3.00
6 Pin Modular ConnectorCON-102306$0.501$0.50
Red On/Off Rocker Switch with Indicator LightSWT-102050$4.001$4.00
Battery / Motor Connector (2 - Pin)CON-102310$0.502$1.00

The total was around $200 before tax. I was really happy with TNC Scooters. I called them after I had some problems later on and they were very helpful. I strongly recommend the DC circuit breaker, it protects the batteries and is easier to reset than if you use a fuse. I wired everything with 10 gauge wire from Home Depot. Since I am using 40 amps, I could have gone with 12 gauge but I decided to go a little bigger than necessary for minimal added cost since I may upgrade the motor one day and do not want to have to rewire everything. The 36 volt 3 amp charger works very nicely, it is fan cooled so it doesn't get too hot. It charges the batteries in about 8 hours and then goes to battery maintenance mode.

Choosing a Controller
As far as controllers, there are many options. I think the best controller for this job would have been from Kelly or Alltrax which you could buy from Cloud Electric but they are pricey. Some are programmable which is really neat since you can limit the current or change the throttle response. They also can handle very high amperage. The controller I got from TNC was rated at 40 amps, 1000 watts, and 36 volts and only cost $30. You can't beat that. I figured if it burned out I would replace it with a more expensive model but that hasn't happened yet. One drawback of the cheap controller I bought is that it lacks a reverse feature. There is a way to hard wire reverse with a switch to work around the lack of the controller feature.


I ordered 4 new tires from Dennis Kirk Cheng Shin Front or Rear C829 145/70-6 Tire to spruce up the look of the go kart, I could have salvaged some of the originals but I decided to splurge. They were $17.54 each. FYI, Go Karts USA has a really great table that lists all of the common go kart tire sizes with their dimensions. This is important for projecting the maximum speed of your go kart and selecting the proper gear ratios. Here is a link to the Knobby Tires Table.

Changing Tires (Problem)
It is very difficult to change tires on a go kart. I first tried to separate the bead with a screwdriver and by standing on the deflated tire. This accomplished nothing. I then took it to Pat's garage. We used the auto tire machine and tried to compress the tire to release the bead and it slipped out. We then placed the tire under the lift and dropped the lift on it - nothing happened. These damn things were really corroded in place. A guy named Doc (as in the lawn mower doctor) showed me how to do it. It took about 15 minutes per tire and it was ridiculously hard to do. We put the tire in a vise grip and sprayed the gap where the bead meets the rim with lubricant. Then using various pry bars and working it around little-by-little, the bead slowly released. These are two part rims, once the bead comes off they separate easily.
The original wheels were rusted and had some sharp edges after using the pry bars. They were sanded, primed and painted before the new tubes and tires were mounted. No other difficulties were encountered.

 I also ordered 2 tubes and a steering wheel from Go Karts USA.
7190 Innertube - $12.90 each

Steering Wheel & Cap

Also from Go Karts USA
Steering Wheel: 1801 Steering Wheel, Neoprene 10" Diameter - $43.85
Steering Wheel Cap: add 1877 Steering Wheel Cap

The steering wheel was another splurge and I didn't end up using the cap.

Engine Housing
For the engine housing, I ended up customizing a mailbox that I bought at Home Depot, also found at Amazon
I am pretty happy with the idea to use a mailbox. It allows me to hide the electronic components and mount the charger port and switches. It is durable and cheap. I strongly recommend it.

Here are some more project photos:
You can see the rear of the go kart with the metal platform. The motor has been placed next to the axle sprocket.

Mounting the mailbox over the motor. Batteries placed in the rear and held with a tie-down strap. Wheels and tires are put back on.

Close up of the throttle. We drilled a hole in the throttle from TNC and attached the original cable. I searched for a long time for a cable actuated electric throttle but couldn't find one. This was a nice solution. 

Throttle: Hall vs Pot
When purchasing a throttle, you have to make sure that the throttle is compatible with your controller. The most common type of throttle is a "0-5 volt hall effect". The other is a resistance type throttle which has a variable resistor or potentiometer (sometimes called pot). The resistance is usually given as 0-5K ohms.

Misc Parts
I also bought an on/off switch and power indicator light from amazon. 
GB Electrical GSW-11 Heavy Duty Toggle Switch $6.40 as of 10/7/12, really nice item. solid feel.
Dorman 84926 Red 9/16" LED Indicator Light $7.72 as of 10/7/12, nice item, but this is where I encountered one of my first problems.

Problem with Sprocket
Actually the first problem was the gearing. It turns out that I have a #40 chain on my donor go kart. This can not be changed since the drive sprocket is completely rusted and seized on the rear axle. The motor came with a 11 tooth Dual-D-bore sprocket for a #25 chain. There is no such thing as a Dual-D-bore sprocket for a #40 chain that would fit on my 10 mm motor shaft. I spent hours looking for it.It does not exist.
Sprocket mounted to motor with chain attached. You can see the spot welds from the inner sprocket which was placed inside the larger sprocket.

I ended up having my friend Pat who is a mechanic weld the dual-d-bore sprocket to the original 10 tooth #40 sprocket from the gas motor that came with the go kart. I had to first grind down the dual-d-bore sprocket so that it would slide inside the sprocket that came with the go-kart. This actually worked beautifully, thanks Pat!

It is important to understand how the speed of the motor translates to ground speed of your go kart. Your motor will have a shaft and a drive sprocket will be attached to the shaft. The number of teeth on the drive sprocket needs to be specified (or counted), it is usually somewhere between 9 and 12. The chain connects the drive sprocket to the bigger sprocket which is on the axle that turns the rear wheel. You also need to know how many teeth are on the axle sprocket, 60 is a common number. You also need to know your rear wheel diameter and motor RPM. With this information, you can go to a calculator and figure out the theoretical maximum speed. This site has a Go Kart Speed Calculator
For my go kart, the engine RPM is 3000, the drive sprocket is 10t, the axle sprocket is 60t, and the wheel diameter is 14.2". Here is a screenshot:
As you can see, the max theoretical speed for my go kart is 21 mph. This is pretty reasonable for the street. If the kart was meant for grass and mud, a lower ratio (less teeth on the drive sprocket) would translate into more torque so that it would have an easier time with resistance such as climbing up a hill. The downside of a lower ratio is less top speed. If you have a low power motor, you will never get a top speed over 20 mph so you need to adjust your gear ratio if the speed calculator shows a high top speed. For example, with a 750 watt motor and a predicted top speed of 40 mph, what would likely happen is the kart would barely move at all. The motor wouldn't be able to generate enough torque, it would overheat and the go kart wouldn't be able to handle any resistance such as a heavy rider or drive on grass or go uphill. Proper gearing is important to match the speed and power of the motor to the requirements of the go kart. You may have to change the sprockets on the axle and drive shaft to get the optimal ratio.

Motivation and Research

I have spent much of time and energy researching and implementing an electric go kart for my son's 8th birthday. I have to thank the Internet community for all of the information I needed to do the job. I thought I would repay the debt by providing pictures, videos, and descriptions of what I have learned.

I started by doing a search online of electric go karts that I could buy. You may ask, why not just go with a gas go kart? The fact is that gas go karts are fun, I had one as a child. Along with the fun, there are many potential issues. First (per my wife) is the smell of gasoline in the garage. Other issues are the difficulty in starting especially for a small child. There are maintenance issues as well. For many reasons, I decided to go for an electric option.

Available (New) Electric Go Karts
So there are 2 ready made designs that I considered:

Doesn't get great reviews but not a bad option. here are the specs:

Product Description
The MotoTec Solar Electric Go Kart provides up to a 2 hour ride time with its integrated 4watt monocrystalline silicon solar panel on the rear wing that continuously recharges the go kart while in use. It's powered by a 16Ah 24v battery pack and 350 Watt DC motor that can reach speeds of 15mph. The solar panel can also charge the go kart while not in use or with the battery charger in 4-6 hours. This go kart comes standard with 9 inch pneumatic tires for a variety of terrain and easy to use disc brakes.

Motor: 350 Watt DC Electric Motor
Top Speed: 15 MPH
Battery: Two 12v 16AH Lead Acid (24V total)
Solar Panel: Integrated 4W Monocrystal Silicon (13x9 inch panel)
Battery Charger: Included
Ride Time: 2 Hours (compared to 45min)
Frame: Steel
Rims: Aluminum 2 piece
Tires: 9 inch Pneumatic (9x3.5-4)
Brakes: Rear disc with hand lever
Green: Zero Emissions
Recommended Age: 12+
Max Rider Weight: 150 lbs
Product Dimensions: 48x33x21 inches
Product Weight: 80 lbs
Box Dimensions: 49x35x15
Box Weight: 103 lbs
Warranty: 30 days parts replacement

The next Item that I considered is the
The Razor gets 4 stars but it seems a little puny. Some of the reviews mentioned that the rear wheels could be damaged by hard turning and seem to wear out easily. On the plus side it is inexpensive.

Here is the product description from Amazon: Product Description

Want to give your child a little off-road entertainment? Turn to the Razor dune buggy, the ultimate in electric-powered backcountry cruising. Outfitted with a powerful 350-watt motor designed to reach speeds of up to 10 miles per hour, the buggy is fast enough for serious fun, but slow enough that it won't compromise your child's safety. Parents will also appreciate the side roll cage, which creates a barrier between the rider and the outside, and the padded bucket seat, which includes a seatbelt for added security. And thanks to the buggy's specially designed reduction drive, the vehicle is capable of both lower torque climbing and high torque gearing. Perhaps the coolest feature, however, is the fully electric design, which is not only easy to charge, but requires no fuel at all, runs quietly, and produces no emissions.Other details include eight-inch knobby pneumatic tires, an active rear suspension, a durable tubular steel frame with diamond-plate floorboards, hand throttle and brake controls, a rear disc brake, and a safety flag. Ideal for difficult tracks and terrain, the buggy supports up to 120 pounds of weight and is suitable for ages 8 and older.

Key Features:
For ages 8+
220-pound weight limit
Can reach speeds of up to 10 miles per hour
350 watt motor
8 knobby pneumatic tires
Bucket seats with seatbelt
Powder coated finish on tubular steel frame
Protective padding
Diamond plate floorboards
Hand throttle and brake controls
Rear disc brake
Safety flag
Vertical storage

Product Description
The Razor Dune Buggy provides the ultimate in electric powered off-road capabilities. Powerful speeds up to 9mph and can carry up to 120lbs ! The Dune Buggy's specially designed reduction drive is perfect for lower torque climbing and off-roading. 8" knobby tires and big bucket seat allow for a smooth comfortable ride. Ages 8+

So to compare the two options, Both have 350 watt motors and 24 volt systems. The razor has only 7ah batteries vs 16ah for the Mototec. The Mototec is more expensive and bigger, but with worse reviews and manufactured by a brand that I do not recognize and is not sold in stores. The other is smaller but probably more reliable overall and I could buy it from ToysRus if I choose so that I could easily return it. The Mototec does have a solar panel but I think that has limited usefulness.

Neither options perfectly fit my needs so I decided to research how to build my own electric go kart. Some of the sites that I visited are:

This one is about the Eli-kart. It is by an engineer with vast resources which I do not have. Good info and ideas but hard for me to implement.

This one is about the HDT Kart. It is a kettler kettcar converted into an electric go kart. It seems like a death trap. I think the ideas are very good but the frame is to puny for the power. Also, they used a Ramsey winch motor. This is not a good idea since those motors are not meant to be used continuously, they will overheat and die. Same goes for starter motors which many hobbyists are using.

Youtube has tons of videos showing electric go karts. Many are using golf kart motors, high amperage controllers (400A), and tons of batteries. They do some amazing burnouts and stuff.

One example is the Neurotikart II:
Be sure to read the comments, the author explains what parts he uses.

This next one shows a 70,000 watt motor from an electric fork-lift. It has a 1000A controller and goes about 100MPH.

The best single reference for building electric go karts is definitely the DIY Go Karts forum:
They go into details as to what batteries to use, what motors work, how to figure out gearing, controllers, etc. You can learn all you need to know there.

Honda MiniMoto
Honda MiniMoto Go Kart, image from Amazon, no longer available
The other option I considered was buying a used Honda MiniMoto Go Kart (picture above). These are really cool vintage go karts. Here is a link to the discontinued Amazon listing: . You can read the reviews and the specs. It has a 500 watt motor with a 36 volt system. It goes 18mph and can support an adult. It is a shame that they do not make anything like that anymore. The current commercial offerings pale in comparison.

I searched for a while on Ebay and Craigslist for a MiniMoto in decent condition. They are very expensive and hard to find. I found one on Long Island (about 100 miles away) and was considering paying my brother to pick it up but I decided against it at the last minute. Too much distance, and what if the item does not match the description. I gave up on the go kart and was starting to consider the Honda MiniMoto motorcycle:
They are much easier to find. I found a nice example only 45 minutes away for $300 on Craigslist. My wife convinced me out of it (not really but I didn't think it was worth the fight). She thinks that a mini motorcycle is like a gateway drug to a real motorcycle and she doesn't even want to imagine my son riding a motorcycle.

Next post I will go into my project.