(ET) E20 lacking power

[rtg ee duke edu (Rhett T. George)]

 - Greetings -

Thanks, Marcus, for providing the table of Voltages for armature, field,
and battery.  Speeds 1 - 4 certainly look normal for an unloaded motor.
Obviously there is a 3 V drop from battery to field even in speed 1. 
This may be drop due to wiring resistance and/or diodes.  

Field voltage drop for speeds beyond 4 of 4 to 5 V per step makes sense.  
The field resistance of 18 ohms tells us that the full voltage field 
current is ~2 A.  The surprise is that the field voltage dropped to 5.5
V in speed 8.  The resulting field current is 0.3 A - not much.  I hope
to track down f. w. resistor values in the next day or two.

In the mean time, if a 20 ohm resistor is put in series with the 18 ohym
field and connected to 36 V, the field voltage is (18/38) x 36 = 17 V.
Marcus, you may want to checki your computation.

Best wishes,

                                        Rhett