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Motor requirements

Looking for the best set up to use in my application.  Making a wood hauling cart that would at times be hauling 400# up hill using 13" tires.  But would be used at a low speed(walking).  Would like the longest run time as possible since I'll be using this in the woods.  Thank you kindly - Jim Yuricek

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Hi Jim, I can help with making a list of parts or a kit for your project. We definitely have the parts needed for this project. I need to ask a few questions in order to be able to recommend the right parts for your specific application.

1- What is the maximum percent of grade that the cart needs to be able to go up?

2- Approximately how much run time does the cart need to have?

3- Will the chain go directly to one of the drive wheels, or to a live axle that drives two wheels?

4- If the cart will have a live axle, what is the axle's diameter?

Looking forward to your replies so I can start to build the parts list.

30% maximum grade. That is 30 feet of elevation gain for every 10 feet of distance.

Run Tim - I assume if the cart is hauling 400# up a 30% grade all the time it would drain the battery a lot sooner than if it was running on flat ground. This cart will be used on and off road both flat and hills with all-day on and off use. Is there a solar charger available when the cart is not in use. This cart will be used in the woods with no electricity available.

Drive System - Since this is a prototype I would like to keep it as simple as possible with a direct drive to a keyed sprocket that would turn on a 3/4" diameter axle with both wheels attached. By the term "live" I assume you mean some type of trans-axle that would supply power to one wheel only thereby making turning a lot easier.

A live axle actually drives both wheels at the same speed and power. A fixed axle only drives one of the wheels. And a differential allows both wheels to be powered, but if one wheel looses traction the it will spin and the other wheel won't turn at all, which allows for easy cornering but is not good for using in the dirt. I think the best axle for your application would be a live axle so both wheels will spin regardless of the amount of traction that they have.

I did some calculations and here is what I found.

These calculations are for our MOT-36600G motor which is a 36 Volt 600 Watt gear motor that has a 10 tooth sprocket for #40 chain. I figured out that with a 6:1 gear ratio the cart will have a top speed of 3.1 MPH which is what I consider walking speed. It will climb 30% grades hauling 400 pounds without any hesitation at all.

The 60 tooth rear sprocket for #40 chain and axle adapter should be able to be purchased through a go kart parts supply store. Most go karts have 1" axles though so you may need to use a 1" axle instead of 3/4".

If the cart is going to be running lets say 4 hours a day and going up hills half the time with a 400 pound load then it will need a very large battery pack such as three 12 Volt 35Ah batteries. Since the carts actual usage on any particular day is unknown to me this is just a guess but I think it would have more than enough power for a good days work like you described.

Thanks for the axle info. It sounds like I will be using a 1" axle with a keyed sprocket that will power both wheels. Can you give me pricing for the set up along with dimensions and weight of the components I'll be needing. - thank you again - Jim

Here are some prices and weights of the major parts needed for the project:

MOT-36600G 36V gear motor - $149.95, 12 pounds
SPD-361000 36V speed controller - $59.95, 1 pound
Throttle - $19.95-$29.95, 1/4 pound (many styles available)
BAT-U1 12V battery -  $79.95, 24 pounds (3 of these batteries are needed)
SWT-700 battery disconnect switch - $14.95, 1/4 pound
CHR-S36V4.5AXLR 36V battery charger - $174.95, 3 pounds
CNX-XLR05W charger port - $6.96, 1/20 pound

Other smaller parts will be required to finish the job such as wire, wire connectors, etc.

I look forward to helping you make this a successful project. If you have any questions about these parts or how they work together please let me know and I will be glad to help.

I have a few more questions

1 - what is the motor dimensions? Width, Length, Height

2 - What are the battery dimensions HLW

3 - what kind of batteries are they? Are they the best and latest in technology?

4 - Since the batteries weight 75#, the cart will now need to haul about 500#. Will the set up you provided still perform the same as the 400# specs

5 - What is the output of the battery charger? What is the charging time?

6 - The 60 tooth 40 pitch sprocket is about 10" diameter. If I went up to a 15" tire would it change your calculation much?

Thanks - Jim

PS - I will need a twist throttle and a brake lever. Do they come in different sizes? Right now I'm using standard aluminum pipe with an OD of .050 for the handle bar.


Here are some answers to your questions.

1 - The motor mounting bracket measures 4-5/8" x 2-3/4" with 4 mounting holes. Motor dimensions: 4-1/4" outside diameter x 5-1/2" long excluding transmission and output shaft, 8-1/2" long including transmission and output shaft. Weight 11.95 lbs.


2 - 12V 35Ah U1 battery size: 7-5/8" long x 5-1/8" wide x 7" high.Nut and bolt connection posts. Weight 24 lbs.

3 - They are sealed lead acid batteries which is a very old technology. They are the best technology in regards to upfront cost. We also have the best and newest technology batteries available which is LiFePO4. The price difference between a 36 Volt 35Ah lead acid and LiFePO4 battery pack is; $240.00 for lead acid, and $1380.00 for LiFePO4. We can supply the LiFePO4 battery pack if desired. A 36 Volt 35Ah LiFePO4 battery pack weighs 36 pounds, and the same size lead acid battery pack weighs 75 pounds. Lead acid batteries last for around 300 cycles, and LiFePO4 batteries last for around 1000 cycles.

4 - The motor will still be able to handle the extra weight of the battery pack. The gearing is so low that the extra weight will not have much effect on the power of the motor.

5 - The battery charger has a 4.5 Amp output. The recharge time for a deeply discharged battery pack should be around 8 hours.

6- If a 15" tire was use the top speed would be 3.58 MPH instead of 3.1 MPH. That is not much of a difference in speed so I think it would be okay and the motor would still have plenty of power.

All of our throttles are made for 7/8" OD handlebars or round tubing. We do not have any throttles available for 1/2" OD tubing.

If you have any further questions please let me know.


Just a few more questions before I get ready to place the order.

1 - is there a low battery indicator when the batteries get down to say 20%

2 - what dimensions are the LiFePO4 batteries and how long to recharge?

3 - What company manufactures the motor? I would like a USA made motor.

Thanks again for all your help - Jim

If the motor is a USA made motor how do I go about placing my order?

I will answer your questions below.


1 - When the batteries get down to 20% capacity the speed controller will shut off to prevent damage to the batteries. The power of the motor will significantly drop well before the controller shuts off so there will be plenty of warning before that happens. We have throttles with built in battery gauges, and we also have handlebar and panel mount battery gauges to monitor the Voltage that the battery pack has in it if desired.

2 - The 12V 20Ah LiFePO4 battery dimensions are 7.13 x 2.99 x 6.54 inches. Two 12V 20Ah LiFePO4 batteries are the same size as one 12V 35Ah U1 lead acid battery, so there is no size difference between a 36V 35Ah lead acid battery pack and a 36V 40Ah LiFePO4 battery pack.

3 - The manufacturer of the motor is Unite. They are a Chinese factory and the motor is made in China. We do not have any motors that are made in the USA. We would like to have motors that are made in the USA but we do not know of any US manufacturers of the type of motors that we sell.

The best way to place an order would be for me to make a kit of all the parts that you need so we can make sure that all of the parts are compatible and work well with each other. Then the order could be placed by phone or online. I will give you the item number of the kit after it is made for ordering by phone, and I will also provide a link to order it online if you prefer.

You could of course order by phone or online without me making a kit by providing the item numbers for the parts that you need.

If you would like for me to make a kit please let me know which parts you decide to use, and then I will go ahead and make the kit and reply back to you with the kit item number and link.

If you have any further questions please let me know and I will be glad to answer them.

Thanks again for the info. I need a left side brake lever and the grips for both sides of the 7/8" bar. Please include the batteries with the kit.

I went ahead and made the kit and its cost is $675.00. It is item # KIT-150. Here is a link to it:

If you have any questions or would like any changes made to the kit please let me know.

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