> > >1. Measure the resistance of the motor at zero RPM (zero backEMF). This can >be with a variable current power supply by applying a fixed current and >measuring the voltage across the motor. Resistance is volts/amps. This >wiring resistance is the fixed resistance of the motor. All losses in the >wiring resistance show up as thermal losses in the motor. > >Do you mean I should find/get an adjustable power supply type thing from >Radio Shack and connect it directly to the motor, and then use my multimeter >to measure the voltage as the motor runs at a specific number of amps? > Yes and no. The power supply is correct, but you need one that can put out lots of amps at very low voltage (say 20-30 amps at 1 or 2 volts). Secondly you do NOT want the motor to spin, if it spins it will generate Back EMF and invalidate the reading. You need to hold the shaft with something and prevent the motor from turning. Apply one or two volts and then 'rock' the shaft back and forth a little to find a position that draws the most current. Measure botht he current AND the volts at the same time I.e. don't measure the volts and then connect the motor, the voltage might sag so you need to measure it while it's drawing that amount of current.
> >2. Measure the current <through the motor> on a second by second basis >during a test drive. This can be done with an emeter connected to a laptop >in the car. > >I take it this would be separate from my current E-meter/Link10, since that >measures battery amps, not motor amps. Do I need another instrument, or can >I use my multimeter? > Correct. You can use your multimeter as long as it will work with an external shunt. I doubt you have a multimeter that can directly measure hundreds of amps (remember this is DC amps so a clamp-on meter probably wont work, though it depends on your meter).
