24V 23A Simple controller for skateboard

I would like to use a 24v 23a simple controller for a 450 watt skateboard.
I am finding that programmable brushed speed controllers with R/C
input are becoming difficult to come by and as such I would like to know
if this motor controller would be acceptable for a Unite Motor 7618, 24 volt
450 watt running on 6s lithium batteries. It is geared pretty low so
the start up amps are not too radical, but , I have no readings as to
what the actual start up amps are. It is rated at 18 amps continuous.
A soft start is optional and little to no braking is desirable as braking can be
dangerous on a stand up skateboard. Also would the asymmetrical programming
option be used to advantage here?
Thank you for your time.
Bob K

Hello, Bob.

I am not sure how well the 24v23 SMC would work with that motor. If you could characterize how much current it would draw when fully loaded (e.g. with a person standing on the skateboard), both at start-up and during normal operation, you could probably get a better idea of whether or not that SMC would work for your system. In general, if you design your system in a way that the controller does not need to handle more than 23A continuously, it could work for you.

Also, please note that we do not recommend using our products in applications where their failure could result in injury.


I will be running less than 18 amps continuously.
It is the peak start up amps that I am asking your professional opinion on. I don’t know
you don’t know, I know.
I am under geared and get up to speed in like 2 seconds and run maximum RPM
pretty much all the time. This is by design as
I want to limit my top speed for safety reasons. Your SMC could work under these
conditions. I have 2 questions.
Can I add heat sinks if needed? If so, what configurations would you recommend.

What does the Asymmetric button do in the set up program?


I should add that I have used a Syren 25 amp controller sucessfully
on this board. But with no programmability, the 100%
always-on regen was too much braking for safe operation on a board.
I want a soft start and little to no braking.

Without limiting its acceleration, a brushed DC motor can draw up to its full stall current during start up. Unless you know the stall current of your motor, it can be difficult to be accurately assess whether or not a particular controller would or would not work in your system. If this information is not available in the motor’s datasheet, and you already have the motor, you could measure the stall current yourself. If you are not sure how to do this, let me know.

If the heat sinks fit inside your setup, I do not see why you could not add them. We do not have any recommendations on how to add heat sinks.

The Asymmetric feature on the Motor Settings tab allows you to set different hard limit values (Max speed, Starting speed, etc.) for forward and reverse.


Yes, would you please let me know the proper way to determine the stall current.
I am concerned with hurting my Lipos ( ~2c)though. Is it short term enough that I
am worried about nothing?
On the asymmetric feature, can I move the zero cross over between forward and reverse
to “soften” the transition to reverse? ( or even eliminate reverse altogether? safety reasons).

Bob K

In general, to measure the stall current safely, you can briefly stall the motor at a low voltage, which will limit the amount of current that is drawn during the stall. Then you can linearly scale the value of that current to approximate the stall current at the voltage you intend to supply in your project.

In your case, it might be okay to use your 2S LiPo batteries to supply a relatively low voltage to your motor, depending on their capacity and maximum discharge rate. You can read this blog post about battery capacity to get a better idea of whether or not they could supply enough current. If you have access to an adjustable power supply, you could use it to gradually increase the voltage until the motor starts turning. Then, you can stall the motor by completely stopping the rotation of the output shaft, and measure the current with an ammeter (or multimeter). You could then use Ohm’s law to estimate the stall current at the voltage you want to supply. For example, if you supplied 5V and measured 1A, the coils have a resistance of 5ohms. So, if you wanted to supply 24V, the current draw would be 24/5 = 4.8A.

As for your question about eliminating reverse, you could check the Asymmetric box and enter a value of zero in the Max. speed field of the Reverse column.


Thank you Jonathan!
It just so happens that I have the use of a power supply to perform just the test you outlined.
I will report back next week.
Bob K