Newman machine geometry

[Eddy Currentz]

I rebuilt my Newman motor by getting rid of the cardboard tubing. I wanted to compress the windings a little, realign the bearings, rebuild the rotor and clean things up a bit.
What I found was a motor that didn?t work even half as efficiently. A 9 volt battery that usually lasted at least 10 hours, barely lasted 3. The coil shape definitely made a difference.
I spread the coil back out, making sure it was as high as the rotor, and the batteries were happy again. This obviously suggests a geometric element since that is the only thing that made the difference for my motor.




I am planning to rewind this motor to see if a more contoured winding makes any difference.
A sulfated lead acid battery works well with these motors because it more easily converts the BEMF into usable current, and the 9 volt gives it some voltage. Together they can get some efficient work done on a motor like this that doesn?t have much of a load.


Here?s the commutator:

[Eddy Currentz]

I added another dead 12 volt battery to the series last night. It had been sitting around for a long time and only showed 6 volts across the terminals. The 9 volt had dropped a volt so I wanted to slowly remove it from the chain.
I replaced the 9 volt this morning with 2 dead, 14 volt drill batteries. They only measured 4 volts in series. They are NiCads so I want to see if they react the same as lead acid batteries.
So far this motor has been running for three days on one 9 volt battery and two dead 12 volt batteries. The 9 volt dropped 2 volts but the lead acid batteries held their voltage.
Can anyone here tell me why "dead" batteries work in this motor?