I can't seem to find the spec sheets anymore on the net. As I recall, we had a couple to choose from but we weren't sure which was the right one.

Swath, you need an adjustable power supply. I have an Agilent but they are kinda spendy. May I suggest you just used D cells? This will give you testpoints for 1.5, 3, 4.5, 6, and 7.5 volts. should be enough to get a decent data set so you can match it up.

I'm having a little trouble with this. I believe this is the 'possible' spec sheet for our motors.

http://www.cnmotor.cn/en-p3.htm

To look at the chart, none of the 385's operate below 4 Volts which ours obviously do. The current ratings are all much lower than what you measured and they are applying up to 24 volts to get them to do that. I am assuming the no-load values were taken at the nominal voltage they call out. Something is not jiving.