# Which voltage to use for my motor controller if I connect two motors to it?

I am embarking on a robotics project. As a part of that I will be connecting two motors to a motor controller designed for two (+1) motors. Each motor has voltage 6-12 V and the motor controller has 5-24 V.

My question is how does the motor controller distribute voltage from the power supply? If I connect 24 V to it, will that be too much for my motors? Or will it be evenly distributed between them?

Here are the motors I am using: Premium N20 Gear Motor (298:1 Ratio, 90 RPM)

And here is the motor controller: TReX Jr Dual Motor Controller

Sorry if the question is basic, I am just getting into this and trying to understand what means what.

Edit: Thank you for the answer!

• A dual motor controller is just two separate motor controllers on one board. What does that tell you? And yes, 24V definitely too much. Commented Nov 12, 2021 at 2:15
• The controller doesn't distribute the voltage between motors. You can eventually use 24v for 12v motors, but the problem will come when you set the speed above half. Then the average voltage applied to the motor will be more than 12v what can cause a motor damage/overheating.
– user208862
Commented Nov 12, 2021 at 3:15

how does the motor controller distribute voltage from the power supply?

It distributes the voltage to each motor in parallel, so each one is independently connected to the full supply voltage. If you apply 24 V then each motor will get 24 V, which is way too much for 6-12 V rated motors.

DC motors require thermal conduction to stay safe, and not endure unreasonable loss of reliability from temperature rise.

General Rule of thumb is 85'C winding temperature or <= 10% of locked rotor = start current. This implies the current should not exceed 10% of 1.6A after a brief startup. You achieve this with averaged current sensing using PWM.

I suggest a 50 mV current shunt and LPF.

Voltage (Nominal)   12V
Voltage Range (Recommended)     6V - 12V
Speed (No Load @ 12VDC)     90 rpm
Current (No Load @ 12VDC)   70mA
Current (Stall @ 12VDC)     1600mA
Torque (Stall @ 12VDC)  70 oz-in


How you may choose to regulate current , at least have have an intelligent acceleration max constant value and braking profile with current and velocity feedback along with fault detection protection.

• This... appears to be answering an entirely different question from the one being asked. Commented Nov 12, 2021 at 3:31