Register to reply

12v dc motor speed self limited?

by moroeder
Tags: 12 v dc - 24 v dc
Share this thread:
Nov17-11, 07:29 PM
P: 1
Fellow Engineering Lovers,

Being a mechanical with limited electrical I must turn to the electron masters for answers. I have a PM brushed DC 12 V fan motor on of a standard electric cooling fan on a car radiator. My calculation comes out to be about 90 watt. I also have PWM 12-24 power source 50 amp that appears to work properly. However the fan in the pushing air direction will only swallow 16.5 volts. In the puller direction 13.5 volts with both at about 10 amps.

I am running the controller on the 24 volt input and with no load I have about 26 volts. The PWM is a very robust piece out of our US military equipment. No heat to speak of and you can certainly tell when the system is turned on because of draw down of the other equipment running in the car. I have an air cooled engine and want to move more air over it by spinning the fan blade faster. Sounds good but don't have any idea if it will work.

Finally my question is, "do these DC motors have self limiting voltage intake based on their wattage?" Sounds crazy but what I am seeing seems like it could be so. Please help a mechanical feel the electrons in a more favorable fashion. And if you can steer me in the right direction that would be good too.

Phys.Org News Partner Engineering news on
DIY glove-based tutor indicates muscle-memory potential
Tricorder XPRIZE: 10 teams advance in global competition to develop consumer-focused diagnostic device
Study shows local seismic isolation and damping methods provide optimal protection for essential computing equipment
Nov17-11, 08:08 PM
Sci Advisor
PF Gold
dlgoff's Avatar
P: 2,726
Welcome to Physics Forums moroeder.

Quote Quote by moroeder View Post these DC motors have self limiting voltage intake based on their wattage?...
Yes, so to speak. The magnet wire used to wind the magnets has resistance which will rise depending on its temperature. So the wattage of the motor tells you how much current and voltage you can supply without overheating it until failure.

Register to reply

Related Discussions
Why is the speed of light limited to a countable number General Physics 4
Dc motor speed and torque Electrical Engineering 7
AC Motor speed control Electrical Engineering 8
Help with dc motor speed Electrical Engineering 7
Is wavefunction collapse limited by the speed of light? Quantum Physics 1