DC Electric Motor Voltage/Current

[Pete in CDA]

Good Day,

I have an older Prestolite DC motor that is installed in a 1979 Ford Fiesta.  I want the Fiesta to be capable of getting on the local freeway.  I've seen where motors are somewhat "Flexible" when it comes to the voltage in.

It says (about Power),

Nameplate 10hp
96v/200 amps
96v/400 amps
Voltage Continuous 96 vdc
Current continuous 180 amps

The questions I'd like to pose are;

What's the highest voltage I "Should" put into it without pushing too far? (What I'm wanting is 120 vdc)
What's the highest current I "Should" put into it?

Pete in CDA

[leitmotif]

Pete

I am a motor control electrician.
I would follow the motor nameplate rating give or take 10%.  You may be able to get freeway speed at 120VDC and or you may overheat and possibly burn out the motor.

You dont put current into a motor.  The motor demands current.  Here basically is how it all works

The torque demanded by load (car) is what the motor must meet.  If it can meet it all is OK.  If the motor can deliver more torque than demanded it will speed up - if not it will slow or stall.
HP = Torque x RPM divided by 5252
HP = 746 watts
Watts = I x E
Juggling the formulae you get
I = T x RPM divided by 5252 and V
Car is basically a constant torque load. 
So as you speed up
RPM goes up
HP goes up
and assuming V constant
I goes up.

Dan Bentler

[Paul]

It sounds like you have a Prestolite MTC series motor. That is a very tough motor, I've built 2 EVs using these motors (a VW Rabbit Pickup and a electric Manx style buggy.)

Can you find MTC-4001 (or perhaps 4002, 4003, ect) on the motor tag? Does the motor weigh about 100 pounds? The MTC is a 4 pole motor with 8 brushes (2 brushes in each position.)

The fairly common Prestolite MTC series motors can easily take full power from a Curtis 1221 or 1231 controller. They can drive an EV up to about 3000 lb. with minimal concern about overheating. The upper limits are generally quoted to be about 150 volts and up to 1000 amps briefly at lower voltage. The motor application is similar to the ADC 8 inch motor but its slightly smaller. The maximum voltage is slightly lower, the continuous current is slightly lower but the over-current ability may actually be slightly higher (they have generous brush area.)

Here are some pictures of an abused MTC Prestolite that Jim has brought back to life http://hitorqueelectric.com/gallery/v/custom_motors/Hack+vs+Husted/

HTH

[Monermaje]

when you say "Voltage and load remain the same" are you talking about the current, or the mechanical load? if you have a current limited supply, then there will be no increase.
I suppose that, depending on the number of segments in the commutator, your idea may increase the torque some. But if if the motor can handle the extra heat that would be developed, it would probably be easier to just increase the voltage.
Since the extra winding you would be energizing would not be in the optimum location in the magnetic field, the gain will be limited .
If there are too few commutator segments, and you energize a coil that is in the totally wrong part of the field you could either get no gain or maybe even reduce the torque.