# [Solved] Motor Amp Draw Problem

I hooked up a potentiometer to my motor controller today. The controller goes to the right wheel motor and has a port for a  potentiometer to control the speed of the motor. I wanted to reduce the speed a small amount so that when I am ready to test the robot's drive system the robot doesn't drive away at 50 miles per hour. Every electrical system in the robot is protected by its own fuse in case there was ever a short or something went wrong, that way the fuse would blow rather than shorting out a few hundred dollars worth of electronics.

What I found today while testing the motor was that as soon as I put a load on the motor I would blow the fuse that protects the motor controller. I put in another fuse (10 amp) and used an amp meter to test the no-load amperage which was about 2.5 volts. Then when I applied load to the motor the meter jumped up to about 12 amps and then the fuse blew again.

I looked up the specs for the motor online and I found that with no load the motor should average at about 2.7 which is about what I got but then I saw that the stall current was 133 amps. That is a huge amount and that is why I was blowing a fuse when ever I applied load to the motor. As soon as I apply load to the motor its amperage jumps up to over 30 amps. This is normal but I have did not expect this when I first assembled the circuit. Luckily fuses are easy to replace so I put in a 50 amp fuse and now everything is working fine.

These are the electrical specifications for the FIRST CIM motors that my robot uses:

FIRST CIM Motor Specifications:
Performance
ModelM4-R0062-12
Operating v: 6v - 12v
Nominal v: 12v
No Load RPM: 5310
No Load A: 2.7A
Stall Torque: 343.27 oz-in2424 mN-m
Stall Current: 133A
Kt: 2.58 oz-in/A18.2 mN-m/A
Kv: 443 rpm/V
Efficiency: 65%
RPM - Peak Eff: 4614
Torque - Peak Eff: 45 oz-in/A317.8 mN-m
Current - Peak Eff: 19.8A