X-Treme XM-2000 Discussion continued from EVT America Z-20a and Z-20

The two-speed set up of the XM2000 just seems like an unnecessary feature. One of the advantages of DC electric motors is that for a given voltage input, they only produce more torque the slower they are going.

and

On the XM, it is unknown if the shifter is shifting gears, enacting different windings, or some other method which, if known in detail, may be found to be far more desirable/undesirable than simply altering the voltage.

(A) To address the desirableness of the feature: One advantage that can be seen is that the low speed setting does stress the batteries less for 0 to 20 mph acceleration - even when accelerating at the same rate. This is indicated by seeing less voltage drop when using low speed. Therefore, I'd say that it is a worthwhile feature.

(B) To address the torque characteristics: There are many different types of DC motors (series and shunt being just two) - they have different torque characteristics - so PJD's comment although true seems a little broad to apply to this situation. As usatracy points out we need to know much more about (a) the nature of the motor windings & (b) the nature of the shifting mechanism to figure anything more out in theory. However, in practice see (A) - it is worthwhile for me.

FWIW, my guess is that it's enacting different windings. I'm sure usatracy will take his motor apart soon ;-)

John H.
Blue XM-2000
Ann Arbor, MI
http://www.revevllc.com