Measuring AMPS

[Pete B.]

What is the best most accurate way to measure the AMP draw of the motor?

Pete

[AndyKunz]

The "most accurate" way will show the waveform of the commutation of the motor.

Get yourself an Astro "Whatt Meter" they make several varieties all are good. www.astroflight.com

Andy

[Pete B.]

Right now I'm using a digital multimeter, so my question is where should I place my leads to measure the amps and should the boat be in the water?
Good luck in MI

Pete

[Bill Sellers]

Pete,

Your multimeter needs to be inline (series) between the motor and the speed control. That way you are measuring the amps to the motor and not out of the battery. The Astroflight Whatt meter is ideal for this because it is designed with this hobby in mind. In other words, the meter has two leads to hook up to the motor, then the meter, and two leads to hook up to the source of power. The other nice thing about the Whatt meter is that it will measure and display simultaneously the input voltage, the load (motor) current, the wattage and the milliampere-hours consumed.

Take the measurements with the boat in the water so the the motor is loaded by the prop working. The free running (not in the water) measurement is meaningless.

Bill

[Dunk]

Unless you've got one heck of a meter, most won't measure more than 10 amps, you would have to get a calibrated shunt with a known voltage output. An awful lot of trouble to go to when there is a better, fairly inexpensive, device available.