This forum is in read-only mode. Please continue to browse, but replies are disabled for now. Why?

Autocross electric Razor Ground Force build from scratch

I just purchased a Razor Ground Force Drift for $15 and I want to get my son into the Kart class with my autocross club. That being said, distance is not the goal but it is available torque, weight savings and traction on a course through cones lasting maybe 50 seconds. I want to utilize only the frame so I am open to the best parts configuration for the goal. I also purchased a used Schwinn s750 24v for $75 in working order. I would appreciate your advice on batteries (lithium?), controllers, tire swap for traction and if the 750 motor is the route or should I just use it for transportation when at the track and look at other motor options (brushes or no). Thx in advance.

The first step I would take is to figure out the wheel swap to make sure that it has wheels. Standard non-drifting Razor Ground Force wheels do not fit the Razor Ground Force Drifter because their hubs are too narrow for the Drifter's axle. The Ground Force Drifter axle is 20mm so standard go kart wheels will not fit onto it. What you might want to consider is replacing the Drifter's original axle with a standard go kart axle so that go kart wheels could be fitted onto it.

As far as motors go the Schwinn S750 motor is rated at 750 Watts which should make a little over 3/4 horsepower. This motor is good for a gear ratio with a top speed of around 20 MPH on flat ground however at that speed it will not have much low end torque for fast take offs. It could be geared for a lower top speed to give it a faster take off speed though. For faster take off speed and a fast top speed a larger motor such as a 1000 Watt, or even two 1000 Watt motors could be used. Two 1000 watt motors would be pretty fast in that kart.

The speed controller simply needs to be rated at or above the Wattage of the motor. If two motors are being used then two speed controllers could be wired up to one throttle.

Lithium batteries are half the weight of lead acid batteries however they cost four times more so they can get expensive. They are also much more limited in the amount of Amps that can be drawn from them than lead acid batteries are so they are probably not a good choice for a go kart that needs to run fast for a 50 second race. Lead acid batteries are most likely the best way to go with your type of build since they can put out a large amount of power in a short amount of time.

Please let us know if you have any questions.

Good info on the axle/wheel challenge. Can you send we a package deal on the 1000w and controller please. Anything else required? Throttle setup or charger? Let me know if you can put together a plug and play for a good price point shipped to 32750.
FYI I would buy the batteries locally.
I can make a kit out of all the parts needed to make a complete electrical system except for the batteries. To make a complete kit the following parts are required.
  • Motor
  • Controller
  • Throttle
  • Power Switch
  • Battery Charger
  • Charger Port

1000 Watt motors are available in both 36 Volt and 48 Volt versions. The Voltage makes no difference to the amount of power that the motor has, only the Watts rating determine the motor's power. A 36 Volt battery pack requires three 12 Volt batteries, and a 48 Volt battery pack requires four 12 Volt batteries.

What Voltage do you want the motor in the kit to be?

It would be 36V
Okay 36 Volts. I forgot to ask this question in my last reply. So I can figure out which size battery charger to include with the kit, do you know the Ah rating of the batteries that you will be using?

If you are not sure what the Ah rating of the batteries will be right now then I can make the kit without a charger.
I figured 9 or 10, thoughts?
Most 9 Ah SLA batteries are rated for 25 Amps of maximum discharge current and 10 Ah are rated for 28 Amps of maximum discharge current.

Our 36 Volt 1000 Watt controllers have a maximum current draw of 40 Amps so I would not recommend using them with 9 Ah or 10 Ah SLA batteries. Although if the cart will only be used for 50 seconds at a time then 9 Ah or 10 Ah SLA batteries might work okay with a 40 Amp load. For maximum reliability and so the go kart can be used for practice driving for more than 50 seconds at a time I recommend to use 14 Ah or 15 Ah batteries. Most 14 Ah batteries have a 39 Amp maximum current draw, and 15 Ah have a 41 Amp maximum current draw so they are well within the acceptable specification to use continuously with a 36 Volt 1000 Watt controller and motor.
Ok makes sense. Let us go 15ah and add a foot pedal throttle.
I have sourced an ezip e900 24v 900w scooter and I have pulled the motor which is good but with the controller is dead. I will build a bracket for the.motor I just need a controller recommendation. I would like to run 3 12v 12ah batteries. Can I use a 36v controller with this motor, 660B9? Do I need a SPD 241000 and overvolt? I will be adding a THR-89 foot throttle so any advice there would be appreciated concerning compatibility with the controllers would be great.

Only the motor should be overvolted and not the controller. To overvolt the motor to 36 Volts and run a 36 Volt battery pack either our SPD-CT660B9 or SPD-361000 would work. We are currently out of stock of the SPD-CT660B9 controller however we expect our next shipment of them to arrive in around two weeks. The SPD-361000 controller is a little more expensive then the CT660B9 and it requires a heavy duty switch to operate it however it has a larger aluminum case so it will run cooler and it has thicker battery and motor wires so it is a more heavy duty controller and better suited towards racing then the CT660B9 is. Either controller will work though.

THR-89 is compatible with every controller that we sell including the SPD-CT660B9 and SPD-361000.

Please let us know if you have any questions.

What about the SPD-601000A? It seems that this one would leave the door open for future upgrades. Any drawbacks? Thoughts on overvoting to 48v? The short bursts of the application would make me think ok as it is not like it is on a scooter going full throttle often for great distances.
Does the pedal work with this one?
The SPD-601000A is a great choice for your project and it would leave the door open for future upgrades. It is the most heavy-duty and robust controller that we sell. The only drawback to it is that it does not have low-Voltage shutoff when used with battery packs above 24 Volts. If used with a 36, 48, or 60 Volt battery pack you would want to make sure not to run the kart to the point where the battery pack Voltage was drained too low, otherwise the lifespan of the battery pack might be lowered. A Voltmeter could be installed on the kart to monitor the Voltage so this does not happen. The upside of not having a low-Voltage cutoff on the controller is that the controller will not automatically shut the motor off when the Voltage gets too low giving you the option to run the battery pack's Voltage a little lower than recommended to say for example get the kart back home from a trip around the block or back to the pit stop of a race track.

Heat is what kills electric motors not Voltage, so you could run a 24 Volt motor on 48 Volts as long as it does not overheat. Short bursts of high power typically do not overheat electric motors so running the motor on 48 Volts at full speed for a short period of time would probably be okay for the motor. The RPM of the 24 Volt motor would double when ran on 48 Volts so the kart would go pretty fast at that Voltage.

All of our foot pedal throttles work with the SPD-601000A controller.

Please let us know if you have any questions.

Login or Signup to post a comment