Performance with transistor controller - was (ET) Traction, etc

["Markus Lorch" <mlorch vt edu>]

> > Having had both contactors and now Alltrax I can tell you 
> that the infinite
> > variable throttle is over rated.
> 
> Not in my book!  With the old GE controller, the lowest speed 
> was, for my 
> purposes, too fast in D1.  When sqeezing the ET into that 
> just-long-enough 
> space in my garage, I had to use LL and nudge the speed lever.  Not 
> impossible, but something of a nuisance.  OTOH, the Alltrax 
> lets me creep the 
> tractor forward or backward about a centimeter at a time, even in D1.

Thats a good point David. I hadn't thought of those situations. 
I also typically shift to L before putting it into my parking 
spot, just to be save. 

One thing I would be interested in is if from your experience
you had any loss in raw power. I was thinking that there is nothing
better than having the battery directly connected to
the motor and the motor drawing as much current as it wants.

If we use a transistor controller I think we always loose some
power due to the voltage drop (0.7V I think) at the transistors,
right? (280W at 400A) 

Also the overheat protection/current limiting of the controller 
probably helps prolong the live of the batteries (and the motor brushes)
but may limit us on the torque end as the motor can't draw as high currents
(which
is probably less of an issue with the 300A alltrax controller than 
with the 120A 4QD controller). Right? So I am hoping that some day
I will be able to take my E20 to a tractor pull, then I'd guess a 
controller version may be at a disadvantage?

Any thoughts?

Thanks

Markus