DC Motor Powered by 4 AA batteries

Hey all,

I am doing a project for school which is a competition in my senior mechanical engineering class. The project is building a hacksaw mechanism to cut a 1/2" steel rod the quickest. The power source given is 4 AA batteries which will power a DC motor we are planning to use.

Our goal while looking for different motors to use is to get the most powerful motor possible with the given power source. We do not care about how long it will last as long as it cuts one rod. We can connect the batteries in series or parallel so we can get 6 volts in series.

How should I go about getting the best motor for this application?

FSU Mechanical Engineering

Hello, Peter.

Our most powerful motors are probably either our 25D or 37D gearmotors. They come in a variety of power options and ratios; you will need to determine what is the appropriate speed to torque ratio for your application. You can use the specifications found in the “Specs” tab of each motor’s product page along with the methods found in the “FAQs” tab for finding the max power and max efficiency conditions for each motor.

As far as powering the gearmotor, you should be able to power all of those motors from 6V; however, please note that speed and torque are proportional to operating voltage, so if you are using 6V and the motor is rated at 12V, its ratings will be approximately half of the listed values. You might even consider using a step-up voltage regulator to get a higher operating voltage from your 6V battery pack if that is allowed. When picking a step-up regulator, I would recommend choosing one that can continuously handle the stall current of your motor (at the output voltage of the regulator) to avoid damaging the regulator.


1 Like

Thank you Brandon, you helped a lot!