How do I slow down a brushless motor with 0.55 milliamps between board and motor

How can I slow a brushless motor down to1/2 of its max operating capacity? I have a 18 V - 4 ah 72 Wh battery? Between the panel and the motor it starts at 0.55 millivolts and sometimes exceeds1.81 millivolts which is a good operating speed. I have contemplated using a potentiometer but if I can pull the trigger to maintain 1/2 of the normal operation speed it maybe okay

Hello @kevinwarren09

Welcome to Digi-Key’s TechForum and thank you for you inquiry.

From the research I have done, it appears the best way to control you motor, would be by using a PWM. I did see some say that you would be able to used a potentiometer or resistors in series, but those may cause more issues than helping. Click here to view some information on the most effective way to commutate with a Brushless DC Motor.


The speed of a brushless motor is determined by the device controlling it. Many brushless motor controllers are designed to yield variable speed in response to some other applied signal, while others such as those in brushless dc fans are more simplistic, and designed to yield the maximum speed possible under the prevailing conditions.

The intended meaning of this is unclear; information about the specific devices in use and the measurements being referred to would be needed in order to offer further comment.

Do you know of an engineer who I can hire to produce 2 or 3 circuit boards to slow the unit down or do I have a on shelf option. The panel and the motor starts at 0.55 millivolts and sometimes exceeds1.81 millivolts however the new cast should not exceed 1.50 millivolts. Thank you for the help!

Please provide a link to the motor and controller you are using.

Millivolts are not a unit of measurement I’ve ever seen in relation to drive voltage for motors of any kind. Generally the values are 1000 or more times higher. Without details on the motor and controller it is not possible to provide more help.