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Please reccomend kit components

I'm building a custom mobility cart based on a race car. The cart weight with rider to be around 400lbs. It will have 12in dia tires. It will be driven on flat ground with occasional light grades. I want to go 20 mph max (occasionally). It must have reverse. I would like at least 1 hour of ride time. The majority of riding will be at half speed or less. I want the anodized twist grip set and a handlebar mount brake lever with parking brake. I would like to have an adjustable power device so I can power it up the ramps (riderless) into my vehicle without fear of run away. My other scooter has a "jackrabbit" adjustment that does this very well. It controls the max speed and thus the power to the motor. Is there such a feature as a motor brake that auto brakes when the throttle is reduced to off. My PRIDE scooter has this also. It helps when loading as well.  Can a technician put the kit together and test it if I come to your offices?  What is the freewheel feature?

Hi Jon, I can definitely put together a kit for your project. It will need to have a 750 or 1000 Watt motor in order to be able to achieve 20 mph. We do not have any speed controllers rated for motors over 500 Watts that have built in reverse, however we just got in some heavy duty rotary switches that are able to reverse larger motors which could be used.

As far as the adjustable power device that limits the amount of power that can be accomplished with a potentiometer placed in line with the throttle, the value of the potentiometer depends on the controller model though and requires testing the controller and throttle that will be used in the system in order to determine the value of the potentiometer. Adding an adjustable power device  to the kit increases the complexity of the job and requires extra time for the potentiometer to be ordered from an electronics store after its value is determined. We can do this though.

We do not currently have any speed controllers with motor braking so I am not able to offer that type of controller with the kit.

After a kit has been ordered our technician will put it together and it can then be demonstrated at our offices before it is picked up.

A freewheel allows the wheel to spin freely without any drag from the motor whenever the wheel is turning faster than the motor.

I recommend using the 36 Volt or 48 Volt 1000 Watt motor if geared for a top speed of 20 mph so it will have enough torque to go up inclines. For the battery pack three 22Ah batteries should provide the one hour ride time that you need if the cart was used at half speed most of the time. Or the 48 Volt motor could be used with four 22Ah batteries to provide a longer run time and more run time padding of the battery pack.

Here is a gear ratio calculation I determined using a 36/48 Volt 1000 Watt motor and a 54 tooth rear sprocket for 8mm chain.

Do you have any ideas which Voltage motor and battery pack you would like to use?

After I sent my e-mail, I found that 20mph is pretty unusual and reasonably not attainable. Let's change that to 10-15mph or whatever speed will get me to the 500 watt motor, two batteries and reverse contoller. Forget the adjustable power and freewheel.  

Lowering the top speed from 20 mph to 10-15 mph will cut the weight and cost of the parts in half. I made gear ratio calculation using both a 65 tooth and 80 tooth wheel sprocket. The 65 tooth sprockets gives a 15 mph top speed and the 80 tooth sprocket gives a 12 mph top speed. Here are the calculations:

If it was my cart I would use the 80 tooth sprocket because I prefer hill climbing torque over top speed. However both gear ratios are acceptable to use with a 500 Watt motor. For a one hour ride time on flat ground with the occasional light grades I recommend using two 12V 22Ah batteries.

I can put together a kit for this project. I need to ask some questions before I make the kit so I can narrow down which parts to include.

  • Do you want the motor to have a bottom mounting base, or to mount from its ends?
  • Do you want a panel mounted key or toggle switch, or prefer a handlebar mounted power switch?
  • Is a handlebar mounted reverse switch OK, or do you prefer it to be panel mounted?
  • What size wheel sprocket would you like to use?

You've punched my button. This sounds a lot better. Please proceed with a kit with the following:

1. Motor with base (Mot 24500x2500B)?.

2. Panel mount key switch.

3. Handlebar reverse switch

4. 80T rear sprocket. Chain will be #25? Does the motor sprocket 

    with 11 teeth and chain have wear problems being so small? 

5. Full twist throttle set, anodized Blue (THR 124)?

6. Include brake lever LEV-26

7. Include Volt Meter Met-120V-blue

8. Include Brake cable CBL-101 and BRK-228 adjuster

Let me know if these additions/substitutions are compatible. Do I need a circuit breaker/fuse or is one included? Let me know what the total cost will be and when 

the kit will be ready. I might drive up from Orange County to pick it up and pick your brain some more.


As long as the #25 chain is kept well oiled and is not run dry then it should last a long time.

We always include a fuse holder and fuse with each kit. Kits usually take us around 1-2 business days to build after the order is placed and if it will be picked up locally then we will let you know when it is ready.

We are in Santa Cruz County which without traffic is an 8 hour drive from Orange County however if you feel like making the trip then you are welcome to pick the kit up in person, or we could have it shipped to you with FedEx. I went ahead and made the kit which is linked to below.

Item # KIT-138:

Please let us know if you would like any changes or additions made to the kit.

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