On 12/30/2016 12:32 AM, Roland wrote:
Hello Jay, Another test you can do, is take a ohm reading at the motor terminals. Rotate the motor by hand and see if the meter shows a pulse as it rotating.
As I rotate the shaft by hand, the ohm meter goes negative (I assume due to current/voltage being generated by the motion.) So I paused the rotation every 5-10 degrees to take a reading. My high/low resistance were 0.5 and 0.2 ohms (I had a lot of 0.3 and 0.2's flashing back and forth, so the average was probably around 0.25 ohms).
Then disconnected the motor controller leads from the motor. Next, take a reading from each motor terminal to the motor housing. A new motor that is brush dust free, should read about 20 megohms or as a open circuit. I do this every time with a new motor or when the motor is clean.
I cheated a little bit here. I just checked resistance between the motor + and - leads (The motor +/- was disconnected from the controller, but the wires connecting the two fields was still in place, so essentially all 4 motor terminals were in series.)
I tried resistance readings from both the + and - to the truck chassis, the metal case of the motor, and the front shaft of the motor. All readings were no connection (sometimes starting at 35 M ohms and quickly going up to 0L)
Question: Because neither the +/- terminal had any measurable connection to the chassis of the truck or the motor, am I safe in assuming all 4 terminals don't need to be disconnected and measured independently?
Jay _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
