How to choose the correct motors and batteries for my robot

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Hello all,

I am building my first real robot on my own and am running into some difficulties. I do not know how to choose the correct motor or batteries to use in the robot. I’ve calculated that the robot will be roughly 90lbs and I will be using two motors in order to move it. It operates on three wheels. I have used the sizing calculator on this site and got:

Angular Velocity: 9.000 rad/s
Torque: 1.7018Nm
Total Power: 15.316W
Maximum Current: 0.76582
Battery Pack: 3.8291Ah

I was looking at using a drill motor but I do not know all of the differences or what I should use. Brushless or not brushless? Impact Driver motor? 20VMax batteries?

Compact drill
DEWALT 20V MAX XR Brushless Drill/Driver, Compact - Bare Tool (DCD791B)

Impact drill
DEWALT 20V MAX XR Impact Driver, Brushless, 3-Speed, 1/4-Inch, Tool Only (DCF887B)

Compact 20VMax batteries (2Ah)
DEWALT 20V MAX Battery, Compact 2.0Ah Double Pack (DCB203-2), Yellow

20V max Batteries (5Ah)
DEWALT 20V MAX XR 20V Battery, 5.0-Ah, 2-Pack (DCB205-2)

I also do not know what to get as a motor controller. If there are any suggestions for controlling drill motors that would be much appreciated.

3

Hello @DS123 and welcome to the RobotShop community,

It is awesome that you’re building your first robot! I hope you’ll share some pictures/videos once it is finished :grinning:

For wheeled robots it is recommended to use brushed DC motors. If your robot is close to 90lbs and you are planning on only using two drive wheels 1.7018Nm seems a bit low, for heavy robots like yours a good option would be using gearmotors. A good option is this motor and gearbox combo:


If you need help selecting the battery this guide can help you:

But in general terms, you should check that the battery has the same nominal voltage as the motors, and that the capacity and discharge rate are enough for the motors.

If you need help choosing the motor controller you can check this tutorial:

I hope this information can help you

Let us know if you have more questions