Will my motor controller die if motors stall due to insufficient current?

Hi all,

Great forum! My first post…

Just wondering if my motor drivers or motors will die if there is insufficient current being delivered.

I have a Rover_5 from DF Robot that has four of the following motors -

  • Motor rated voltage: 7.2V
  • Motor stall current: 2.5A
  • Output shaft stall torque: 10Kg/cm
  • Gearbox ratio: 86.8:1
  • Encoder type: Quadrature
  • Encoder resolution: 1000 state changes per 3 wheel rotations
  • Speed: 1Km/hr
  • Four motors
  • Four encoders
  • Encoder interface:

My Romeo for Intel Edison board (and other motor driver boards that i have) has the following specs.

*Operating Voltage :5V
*Output Voltage :5V/3.3V
*Input Voltage(limits) :6-20V
*Digital I/O pins :14
*Analog I/O pins :6
*DC Current per I/O Pin :10mA
*Motor Driver Constant Current :2 x 2A

So, on the one hand, I have 4 motors with a combined stall current of 10A (5A for each pair of motors in parallel) yet my motor controller board can only deliver constant current - 2 x 2A.

Anything that i should be worried about?



The short answer is “YES” you should be worried.
The long answer is more complicated.
First, the stall current of the motors is NOT the operating current. The stall current is when the motor is blocked from turning and is the maximum current it can draw. In normal operation the current will be somewhat less, maybe around 1/3 to 1/2 that. But it’s always good to be prepared for worst case.
Second, The motor drivers “may” have current limiting / overcurrent protection. I don’t know. I haven’t looked into your particular setup. If so, that will usually prevent the motor drivers from burning up. Key word there is “usually”
Third, it is usually best to “derate” components. That means to run them at lower than their specified maximum for any particular rating. In this case, the motor drivers are rated at 2A constant so it would be a good idea to run them at 1.5A or less. You don’t state the normal operating current of your motors, but if we use the 1/2 of stall current I mentioned above, that is still more than the 1.5A derated current.
There are other factors I won’t go into. To sum up, you might could get away with using that setup, at least for a while, but it isn’t really a good idea. IF the drivers have current limiters they probably wouldn’t be damaged, but counting on that isn’t good engineering practice.
I recommend you get different motors or a different motor driver.

1 Like

Good advice @oldguy,

I’ll get another L298N Motor Controller Module to drive the 2nd pair of motors. Will use an Arduino Mega for the microcontroller if i need more I/O pins…

(I’ll need to look into this more - as i see so many kits with 4 motors but only one motor controller and i’m sure the controller is not the right one - as per your explanation)