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Ok, here is an extrapolated result for the short circuit (stalled) test.
The current at 9 volts would be 3.6 amps. Since I did not wish to burn up
the motor, I checked current readings at both 3 and 6 volts and also
measured the DC resistance and all things point toward 2.5 ohms. I would not
advise stalling this motor while it was running from an un-current-limited
source like a R/C rechargeable battery pack. 9 volts at 3.6 amps is > 30
watts. A motor of that physical size will heat very rapidly at that power
level. Power is proportional to the square of the voltage, so my quick test
at 6 volts for a couple of seconds was enough to start it warming
noticeably, but no harm was done. Of course, neither the off load current of
0.2 amps or the stall current of 3.6 amps tells you anything about its
efficiency at converting electrical power to mechanical power. You really
have to do the dynamometer thing for that.
JB
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In lugnet.technic, John Barnes writes:
> Ok, here is an extrapolated result for the short circuit (stalled) test.
>
> The current at 9 volts would be 3.6 amps...
Holy C..........
That's quite high (understatement) for a little LEGO motor. Do you think
it's possible that the train controller I used in my test didn't produce
enough juice? If that's the case, then the motor has a higher maximum stall
torque than I measured.
TJ
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