Can You Use A Starter Motor For An Electric Go Kart

Can You Use A Starter Motor For An Electric Go Kart?

Hi,

Electric Starter Motor - Bendix Style

Electric Starter Motor - Inertia Style

I’ve noticed that there is a lot of interest with people wanting to use an Electric Starter Motor for an Electric Go Kart conversion. A common question is can you use a starter motor for an Electric Go Kart? To answer this question, we need to understand what is an Electric Starter Motor and the various types that are available so that you can appropriately modify your Electric Stater Motor for use in your Electric Go Kart.

What is an Electric Starter Motor?

An Electric Starter Motor is an Electric Motor designed to start Internal Combustion Engines. Typically, they are designed to turn in one direction only as they have an overrunning clutch which locks the starter gear (pinion gear)  in one direction and it releases it if the pinion gear is rotating in the opposite direction. This prevents the starter motor from burning out if the pinion gear fails to release itself from the ring gear of the flywheel. The starter gear (pinion gear) will engage with the ring gear of the fly wheel of the Internal Combustion Engine when activated to do so. This engaging of the flywheel by the starter motor is done via a mechanism that throws the starter gear in alignment with the flywheel. This throw out mechanism is either done by the inertia of the pinion gear as the pinion gear travels a cork screw type shaft (like in Bendix or Inertia Starter Motors) or more commonly via a solenoid that activates a lever which throws the pinion gear.

Electric Starter Motors have either permanent magnets for its source of magnetic fields or more commonly, field windings, where electro magnets are used instead of permanent magnets. If the starter motor has field windings, you then have to work out if the electric starter motor is series wound, shunt wound or a compound Electric Motor.

What Modifications Do YOU Need To Do To Make The Electric Starter Motor Suitable For An Electric Go Kart?

Modified Electric Starter Motor Installed In Electric Go Kart

Modified Electric Starter Motor Installed In Electric Go Kart

One of modifications you need to make to your Electric Starter Motor to ensure it can be used as a traction Electric Motor for your Electric Go Kart is to ensure that your gear, pulley or chain drive is compatible with the drive train of your go kart. Most racing go karts use a chain and sprocket set up. The chain has a specific pitch and a specific roller diameter. This means you have to have front and rear sprockets that are compatible with the chain. I found that a motorbike sprocket was not compatible with a go kart chain. I have also been informed that the chain and sprockets of racing go karts are not interchangeable with the ones found on hire karts. Since my go kart was a racing go kart, I stuck with the chain and sprockets used in racing go karts. The picture on the left shows a modified Electric Starter Motor installed in my racing go kart with drive train attached connected. I bought a front sprocket (which gets attached to the electric motor; rear sprocket gets attached to the rear axle by bolting it onto a sprocket carrier). Before I could installed the Electric Starter Motor as shown on the left, I had to make some other modifications to the starter motor. The front sprocket had to be attached to the Electric Starter Motor.

I got the front sprocket welded to the pinion gear as shown below.

Front Sprocket Welded To Pinion Gear

Front Sprocket Welded To Pinion Gear

Modified Electric Starter Motor Assembled Prior To Installation Into Electric Go Kart

Modified Electric Starter Motor Assembled Prior To Installation Into Electric Go Kart

The Front Sprocket that was welded to the Pinion Gear was then assembled back into the Electric Starter Motor as shown in the photo on the right. Washers were packed between the Front Sprocket and the retaining circlip to take up any space along the shaft of the Electric Motor. This prevents the pinion gear-front sprocket assembly from throwing out (where previously, the starter motor was designed to throw the pinion gear whilst starting an Internal Combustion Engine).

 

 

Mounting Of Modified Electric Starter Motor Onto Electric Go Kart

Mounting Of Modified Electric Starter Motor Onto Electric Go Kart

The next thing that needs consideration is the mounting of the modified Electric Starter Motor to the Electric Go Kart. Most likely, the Electric Starter Motor will need some brackets made up to mount it onto the Electric Go Kart. Every Electric Starter Motor will have a different mounting points. Some have mounts on the body of the starter motor, whilst most are flange mounted. With my go kart, I used angle iron as I had mount points on the body of the Electric Starter Motor. The Electric Starter Motor was bolted to one side of the angle iron. The other face of the angle iron was attached to the go kart using U-bolts (U-Clamps) so that I did not have to drill any extra holes into the go kart frame. Drilling holes into the go kart frame will probably weaken the frame. Also, as the modified Electric Starter Motor has a lot of torque, I had to reinforce the angle iron to prevent the angle iron from flexing. Prior to reinforcing the angle iron, the angle iron would flex, allowing the chain to come off.

U-clamp (U-bolt) to help with Mounting For Modified Electric Starter Motor For Electric Go Kart. This reduces the need to drill extra holes in the go kart frame.

View from under the Electric Go Kart. U-clamps (U-bolts) to help with Mounting For Modified Electric Starter Motor on to Electric Go Kart. This reduces the need to drill extra holes in the go kart frame. In the photo, the only bolt going through the frame was through an existing hole. No extra holes were required to be drilled.

After the modified Electric Starter Motor was mounted, all I had to do was wire up the Electric Go Kart and it was ready to drive. I’ve noticed that my Electric Go Kart on start up and acceleration, it is pulling over 300 Amps. This gives it impressive acceleration.

 

The major advantage of using U-Clamps (U-bolts) is that you can mount things securely to the go kart frame with minimal modification to the original go kart frame itself. This means you can restore it back to original condition at any time. Also, you don’t weaken the frame due to unnecessary drilling.

 

 

 

 

Conclusion

An Electric Starter Motor can be used for an Electric Go Kart with the following things taken into consideration:

  1. The Electric Starter Motor needs to be modified to suit the drive train and mounting of the go kart.
  2. They can get hot when used. This is because they are only designed to run for 10 seconds.
  3. You need to think about how you are going to cool the Electric Starter Motor. If they get hot, the motor burns out. I’ve experienced it.
  4. It can be difficult to reverse the direction if you don’t remove the over running clutch mechanism.
  5. If your Electric Starter Motor is a series wound motor, changing the polarity of the power applied to the Electric Starter Motor will not reverse the direction of the shaft. You can modify this if you separate the excitation windings and reverse them. With permanent magnet electric motors, changing the polarity applied to the Electric Motor is sufficient to change the rotational direction of the shaft. I believe another way to reverse the direction of a series wound motor is to use a reversing contactor, but I have not tried it myself yet, so I can’t verify it for sure yet.
  6. Electric Starter Motors suck up a lot of amps and can drain batteries really quickly.

Crazy Al signing out.

Al Bunzel, also known as Crazy Al from ElectricCarConversionBlog.com has a passion for Electric Cars, Electric Vehicles and Electric Car Conversions. He has done an Electric Go Kart Conversion using an Electric Starter Motor that came from a small Industrial Kohler Gasoline Engine. You can read more about this conversion on http://electriccarconversionblog.com/electric-go-kart-story-part-1

 

18 Responses to Can You Use A Starter Motor For An Electric Go Kart

  1. Jacques says:

    Very helpfull thank you.

    Just want to know, how does the accelaration work?
    If you put the starter directly onto a car battery, does it go flat out?

    How do you regulate speed?
    Kind Regards

    • admin says:

      Hi Jacques,

      If you put the starter directly onto a car battery, it does go flat out.

      I currently regulate speed with a Pulse Width Modulation (PWM) controller.

      Kind Regards
      Crazy Al

  2. Brandon says:

    What size or rating pwm controller do you use?

  3. admin says:

    Hi Brandon,

    The PWM controller I’m using at the moment is capable of handling over 300 amps. Check out http://www.youtube.com/watch?v=9xcWqqaZ-T4&feature=player_detailpage#t=268s for more details about the the motor controller and the video of the ammeter exceeding 300 amps.

    The implementation of my motor controller is crude and the video explains one of the problems I have with this crude design.

    Kind Regards
    Crazy Al

  4. Gary says:

    Great site. a couple of questions though. What type of a battery are you useing and how long do you get between charges?

    • admin says:

      Hi Gary,

      Thank you for your questions and for visiting.
      I’ve been using a 12 volt car battery for my Electric Go Kart.
      I’ve used Optima Batteries Blue top 34M which is an AGM Lead Acid battery
      and Interstate Batteries Mega-tron II which is a flooded lead acid battery.

      So far, I’ve only been using 1 battery at a time. I get around 10 minutes between charges, but that time varies depending on various factors.
      Some factors that can affect the time are
      * how many corners I have to negotiate. Every time the Electric Go Kart has to negotiate a bend, the kart slows down as the rear axle is a stiff axle and the rear wheels rub. This really shortens time between charges. This can be overcome if I throw my body weight in such a way that it lifts one of the rear wheels. It is hard to explain in words how it’s done but you effectively lean to the outside wheel so that the inner rear wheel lifts up.
      * if I get a push start, the battery will last longer because it does not suck up a lot of energy. If it has to move without assistance, the initial current draw exceeds 300amps. You can see this on http://youtu.be/t27u83oSfEc

      Here is a video of the Electric Go Kart being driven recently http://www.youtube.com/watch?v=NXDRuV3Lqug&list=UU9psqnioh7XG5idF8Dqs-Jw&index=1&feature=plcp

      Are you looking to do an Electric Go Kart Conversion?

      Kind Regards
      Al Bunzel aka Crazy Al
      P.S. If you have any further questions, please feel free to ask me.

  5. Will says:

    Hi, great stuff. I’m wanting to build and electric motor for my boat. Others have used drills and angle grinders with decent results, but low on power and need converters etc. I am not planning on flooring it. but getting good torque with longer time..I can run several batteries in parallel as I have the space…so my question is, if I use a dimmer switch to run the starter motor at a lower rpm, will it last longer? Any idea how I could calculate that?
    Thanks!

    • admin says:

      Hi Will,

      Thank you for your comments and question.

      The first thing you need to measure how much current is your Electric Starter Motor consuming?
      In particular, current draw on
      * start up at maximum acceleration (to get peak current draw);
      * during cruising (to get continuous current draw);

      For example, on my Electric Go Kart, the Electric Starter Motor exceeded 300 amps on start up. Here is the video which shows it.
      http://www.youtube.com/watch?v=9xcWqqaZ-T4&feature=player_detailpage#t=340s

      Once, you know how much peak current and continuous current draw your Electric Starter Motors uses, then you have to find out if the dimmer switch can handle those currents.
      If the dimmer switch can’t handle those currents, then the dimmer switch might blow up or destroy itself.
      Also, is the dimmer switch you are planning to use designed for DC power?
      Also, what voltage is the dimmer switch rated at?

      For Electric Motors to have good torque, you need to pump in a lot of amps.
      Amps give your torque. Up the amps and the torque increases. If you up the amps too much, the windings will fail (and they get really hot) and the motor destroys itself.
      Voltage gives you speed. Up the voltage and the speed increases. If you up the voltage too much, the insulation on the windings might fail or your motor could fly apart – both scenarios also destroy motors.

      The other thing you need to consider when using an Electric Starter Motor as a traction motor is the issue of cooling. Electric Starter Motors are designed to run for 10 seconds and not 10 minutes. With my Electric Go Kart, the modified Electric Starter Motor keeps getting very hot and that is the biggest killer of the motor. Other people have suggested putting cooling fins or liquid cooling the modified Electric Starter Motor.
      I’m currently looking into both cooling options.

      Summary
      Starter Motors were not designed to be used for continuous operation. They were designed for around 10 seconds and they heat up very quickly when used for more than 10 seconds.

      If you still want to use a starter motor, then
      1/ Find out what the peak and continuous current draw of the motor is.
      2/ Find out how much current the dimmer switch can handle. Is it for DC devices? What voltages can it handle? If the dimmer switch can limit current, that might help – I doubt dimmer switches have current limiting capabilities.
      3/ If you want your motor to last longer, you need to implement methods of keeping the motor cool. Heat is the biggest killers of motors and I’ve destroyed some Electric Motors and they were hot when they destroyed themselves. Also, pumping too much current into the Electric Motor cooked the motor.

      Out of interest, what size starter motor do you have? What is it out of?
      What dimmer switch were you planning to use?
      If you can, please post up the details.

      Thanks
      Crazy Al

  6. ryan says:

    hello i am building a electric FWD trike, i was just wondering how you figured your gearing?
    im going to be using a 16 inch diameter wheel, and a gear reduction typer starter motor, no reverse required

    • admin says:

      Hi Ryan,

      With the gearing I did for my Electric Go Kart, I used standard racing go kart drive train.
      The sprocket on the electric motor I think is 11 teeth.
      The axle sprocket had 80 something teeth on it. I did not count it.
      I have other axle sprockets with different numbers of teeth which I can put on if I want to change the gearing.

      What you have to be careful of is if you change the sprocket size, then the chain has to be retentioned which in my case means the motor location has to be shifted a bit to accommodate the new tension requirements.

      If you want to mathematically work things out then here a few things to consider.
      1/ Do you have the circumference of your front wheel? You want that figure in meters. If you have the diameter of the wheel (including rubber), then you can use the formula pi x D = 3.14 X diameter to work out circumference. I realize you mentioned your diameter was 16″, but is that the rim diameter? If it is the wheel diameter, then 16″ = 16 x 0.0254 = 0.4 meters.
      pi x 0.4 meters is about 1.3 meters circumference.

      This means every revolution the wheel turns, the wheel travels 1.3 meters

      2/ Then you have to get the revolutions per second. Usually, rotation speeds are measures in RPM (revolutions per minute) which means if you want to know revs per second, then it is RPM / 60
      So, if wheel is turning at 300 RPM, then the revs per second is 300/60 = 5 revs per second or 5 Hz.
      So, if we continue if the above figures, if your wheel is turning at 5 revs per second, then 1.3 meters x 5 revs / second = 6.5 meters / second which is over 23km/h

      3/ Let’s say you motor spins at 3000 RPM (just plucking a figure out), then that is 3000/60 = 50 revs per second.
      So every time your motor turns at 50 revs per second, and you want to achieve a speed of around 6.5 meters / second, the wheel will have to turn at 5 revs per second.
      That means you need a reduction of 50 : 5 = 10 : 1

      If you don’t get the calculations, don’t worry. Feel free to send me the wheel diameter (including the rubber bit) and the motor RPM and I’ll help you through the calculations.

      Will you be using a chain drive from motor to wheel?

      Regards
      Al

  7. Dee Lern says:

    hi crazy Al,
    I am currently doing an electric go-kart for my final year project. I have a Honda Civic starter motor with me currently, but I am pretty blurred about the specification of the motor. I am doubting the size of the battery that I would need to use. The only information that I have is the current figures @ approx. 95A. Usually how long does it last for a fully charge battery to drain off? From the previous comments, the motor can only run for approx 10s? what if i run in in lets say 15 sec intervals…??

    • admin says:

      Hi Dee,

      There are various factors that affect how long a fully charged battery will last such as
      * capacity in Amp hours (Ah);
      * chemistry of battery;
      * temperature;
      * age of battery;
      * current draw (that’s where discharge curves, usually available from the manufacturer are useful);

      With running a starter motor for around 10 seconds, it then needs a rest until the motor cools down.
      If you run it for 15 seconds, you still need to give it a rest until the motor cools down.
      This is when it is in a car to start a gas motor – a situation where there is more load on the starter motor than what is experienced in moving my Electric Go Kart.

      In my Electric Go Kart, as the load on the starter was less than turning over car gas motor, I was able to drive for more than 10 seconds at a time (in fact, I drove it for a few minutes at a time) because the load on the motor was less. However, heat is still a killer of starter motors and it was easy for the modified starter motor to get extremely hot and I have blown some motors due to over heating.
      That is why I’m looking at liquid cooling solutions for the modified starter motor on my Electric Go Kart so hopefully I can drive for a bit longer.
      If the starter motor can be cooled down, then it can be driven for a bit longer.

      Another thing to watch out for in starter motors is if it has plastic parts in it. For example, I have a starter motor that has a reduction planetry reduction gear system. They are made of plastic so I doubt they can handle being used on an electric go kart where the motor is running for a few minutes.
      Again, I can’t give you a definite answer, but you have to test it out and monitor the temperatures. Just be careful you don’t burn your self as the starter motors can get very very hot.

      What are the specifications for your final year project?

      Kind Regards
      Crazy Al

  8. Barry. says:

    Hi, interesting article. Have you ever considered using a microwave capacitor as electrical ‘nitrous’? Readers.. If you dont understand ohms law, dont even dream it..YOU WILL DIE OR BE SERIOUSLY INJURED

    • Barry. says:

      Google farad power cap on wiki to entertain your your curiousity!

    • admin says:

      Hi Barry,

      Thank you for your comments.
      I have thought of using capacitors as an electrical ‘nitrous’ in the past, but had to put that idea on hold as I’m looking to make the modified starter motor water cooled. Once, I get that sorted, I will have to visit the capacitors again as having a boost button would be fun to have.

      Kind Regards
      Crazy Al

  9. Tony says:

    Hi,
    A couple of questions.
    1. What is the top speed you’ve been able to get out of the motor?
    2. How long does it take to charge your 12 volt battery and if it is not long, can you keep the motor running while you are charging?
    Thanks

    • admin says:

      Hi Tony,

      Thank you for your questions.

      1. I’ve been told around 19 mph (30km/h) by an observer, but I have not tested it with a GPS, yet.
      2. If I use the fast charger at Goulburn Mechanical & Performance Centre (Goulburn Motors), it takes around 20 to 30 minutes to fully charge the 12 volt batteries I use. I have not tried running the motor whilst charging. I’m not sure how the charger would react.

      However, I guess one could put an on board generator using a car alternator run by a small gas powered motor to charge the battery. That would make it a series hybrid.

      I am looking to do some more development on a modified starter motor in the next few months. Things I have in mind are liquid cooling and isolating the negative terminal from the chassis of the modified electric starter motor.

      Kind Regards
      Al

  10. mrjack says:

    tips on modification of starter motor to keep not too hot: 1) use PWM speed controller, 2) modify it from bushing to bearing type, just machined it making hub to fit the bearings. 3) fabricate aluminum heat sink surrounds to your motor. 4) extend the rear shafting for fan to ventilate your motor… that’s it.

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