The motor screen on the commutator side is replaced with a solid band with duct flange.
Now I need a way to control the blower. One option is to use a relay to turn the blower on when the ignition switch is turned on. Another way is to use a programmable speed controller to continuously vary the speed of the blower motor. Guess which option I used? Here is the speed controller:
The Arduino compares the measured temperature to a target temperature – I selected 120 degrees F as my target – to determine the required fan speed. I’m using a feedback control loop, called PID. The Arduino sends a signal to the blower speed controller.
I also connected one of my dash gauges to the Arduino. The gauge once displayed oil level, but now will be displaying motor temperature. The Arduino sets the output signal to the transistor to set the gauge needle based on the measured motor temperature.
My friend Ryan is converting a Volkswagen Beetle to electric. He is going to rig up a similar motor blower for his project. So we took over the kitchen, honed our soldering skills, and turned our ideas into reality.
I installed the system and took a few test drives to see how everything is working. I plotted motor temperature and blower fan speed for a 15 minute drive. About 5 minutes into the drive, the motor temperature reached 120 degrees F. I programmed the system to wait until blower program speed is at 40% before turning on the blower. The blower doesn’t push much air below this speed. After the 15 minute drive, I let the car sit with the blower running to see how long it would take to cool down. I had been hoping for a little bit more cooling capacity. It looks like the blower will be turning at full speed once the motor reaches 120 degrees. The ambient air temperature that day was 90 degrees.