I have been struggling to find correct values for Kt (Torque constant ), Ke (Back EMF constant ) of the motor with 20.4:1 Metal Gearmotor 25Dx50L mm HP 12V (https://www.pololu.com/product/3203/specs).

But they are not close each other.

# As far as I know, Kt and Ke should be same or close each other.

Given the spec, I calculated as below.

Kt = Stall torque / Stall current = 85 oz·in / 5600 mA = (85 x 0.007 Nm/oz-in )/ 5.6 A = 0.1062 Nm/ A

Ke = Rated Voltage / No load speed =12 V/ 500 rpm = 12 / (500 rpm /60 * 2pi ) = 12 / 52.5 = 0.2292 Vsec/rad

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Although they are supposed to be same or roughly close each other, Kt and Ke are totally different each other !!

Taking small approximation error ( 10~20 %) in this calculation into account, the calculated value from given spec doesn’t still make sense to me.

Am I doing something wrong ?

Solving this issue is urgent, so it would be very thankful if you could figure out.