> 
> 
> The resistance thru the starter motor isn't going to change, so at 12.5V
> the amperage is going to have a maximum.  The motor is designed to handle
> this maximum and you cannot accidently exceed it just by jumping more
> batteries to it (in parallel...).

> SStones             Toronto,  Ontario.
> 
> 
> 
  Doesn't the resistance of a DC motor vary with rotational speed? I remember
  something faintly about a counter-electro-motive-force i.e. the motor is
  generating at the same time it's motating. 

  Here at work they always give things with motors a "locked rotor" test to 
  make sure it doesn't catch fire if it's seized. I thought the extra heat was
  due to the extra current being drawn on account of the device not turning.

  I'd like to understand more about the operation of electric motors, so 
  someone please correct me if I am mistaken.

  Thanks,

  Dave