Yup, that was quite the brain fart sorry about that. Since nobody knows 
me here I'll risk further imbarrasment. It would be V/R wouldn't it?
I calculated 120 amps from a measurement of .3ohms and 36 volts. When
I locked the rotor and applied voltage, from a good distance away, I
measured 643 amps. The armature and feild are connected in series.
It was very exciting to actually measure the current but I don't think
I'll ever do that again. 
How can I make a quick estimate of lock rotor amps for a series motor?

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
> Of Olin Lathrop
> Sent: Monday, November 13, 2006 8:20 AM
> To: Microcontroller discussion list - Public.
> Subject: Re: [ee] Best way to control a large dc motor
> 
> 
> > peteHVAC wrote:
> >> I heard tell that measuring resistance of the motor and multiplying by
> >> voltage would give a close value of the lock rotor amps. any
> >> truth in this?
> 
> Martin K wrote:
> > Yes that is true.
> 
> Huh!!?  The units don't even match.  Ohms times volts comes out 
> to Kg m**2 /
> S C**2.  I can't think of how such a quantity is meaningful, but it
> certainly isn't C / S.
> 
> 
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