One compliation of Motor Curves

[neoshaakti]

Is there one compilation of motor curves in existence yet, if so, wanna start one using this thread?

Post all motor curves you have for the 2009 motors.

[kramarczyk]

Here are the motors from previous years... I am still missing one... the Mabuchi RS385SH-2270.

[gburlison]

So I found a spec sheet on the RS-385SH. But the specs are rated at 20V.
Can I expect the performance at 12V to be approximately 12/20 or 3/5 the performance at 20V?
If so will this relationship hold for all specs that I am interested in such as free speed/current and stall torque/current?

Here is the spec sheet:
http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_385sh

[jkessler_22]

Yes, the 12V speed vs. torque performance will essentially be 3/5 of the value at 20V. You can just translate the speed curve (the "N"-line) downward parallel to the existing one on the graph.

The current response is a different story, since current is proportional to torque (speed being proportional to the input voltage). The current draw would follow the same curve (the "I"-line) as shown, but the maximum current (stall current) would be scaled back to the point where the speed curve crosses the x-axis (at zero speed).

This would make more sense if you extrapolated the curves shown on the graph to the 65.7 milli-Newton-meter stall torque and the 6.20 A stall current that the motor is rated for. Then, redraw the de-rated speed curve and a vertical line drawn at the stall point would provide the new expected stall current. In simpler terms, as long as the motor is still rotating, the current draw for a given torque would remain essentially the same regardless of speed.

Hope this helps, without being too confusing !