I'd like for someone to explain how a two speed DC motor works. I have an idea but what I really want to know is how to increase it's speed if possible. Or what determines how fast the motor spins.
This is a windshield wiper motor. The wipers on my 1980 Fiat Spider never did work that great when new. On the fastest speed, the wiper motor runs about 46 RPMS. On a "typical" car, 46 rpms would be the slow speed.
The linkage is not binding, the brushes are good, it just never did work that great from the factory. I've got 13.7 volts at the motor, but I haven't tested it under load.
Doesn't matter if the wiper motor is running disconnected from the linkage or if the wipers are running against a dry windshield.
There are three brushes. One is soldered to the body so it has to be the ground. When power is applied to the grey wire which is connected one brush, the motor spins "slow". Then power is suppied to the blue wire connected to the other brush the motor spins faster.
This is what I can't understand. How applying power to one brush makes it spin 30 RPMs and when power is applied to the other brush makes the motor spin 46 RPMs. Since all three brushes contact the commutator.
I did some experimenting to see what would happen if I applied power to both brushes at the same time. To see if this would make the motor spin faster than 46 RPMs. I figured the worst that would happen would be I would blow a fuse. The motor actually slowed down and no fuses were blown.
If I were to increase the number of windings on this armature (not myself but by a shop that rebuilds starters and alternators) would this increase the speed of the motor? There is room for more copper wire. Or use thicker wire.
I'm assuming this will cause the motor to draw more amps but if that happens and I blow fuses, I can always wire in relays.
Some guy rigged up a DC/DC converter and is sending 16.5 volts to his wiper motor and says the speed increased from 60 to 96 RPMS! But he won't explain where he got the parts. He says it's still in the testing mode. I think this would be hard on the motor after awhile.
I just think there is an easier way to make this motor spin faster.