Romi Chassis Kit -- Motor Polarity


I have this beautiful Romi chassis kit. I would like to know which terminals on the motors are positive and which are negative. I’ve looked at the Romi Chassis User’s Guide and the web page describing the gear motors, and they don’t indicate terminal polarity.

Examining the motors show that one of the terminals on each motor has a blue marking. The other does not. Perhaps the blued terminal is the positive one?

I’m using a Beaglebone Blue as my controller, and I’ll need to solder 1.5mm pitch JST ZH pigtails to each motor so they can get power from the Beaglebone.

Thanks for your help!


Hello, Bob.

The polarity of bi-directional brushed DC motors is not really important in applications like this. When power is applied in one direction they spin clockwise, and when it is applied the other way they spin counter-clockwise. You could install the motors on the chassis and supply power to them to see what direction they turn to get some idea of how you want to connect your pigtails.


Thank you, Derrill!