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

[Rob Brockway <getractor yahoo com>]

Full throttle control is great.  Manuvering is really improved.  The voltage drop looks bad on paper, but when you measure voltage drops on the tractor at high current the .4- .7 volt on the controller is not much at all.

 

Snow blowing is a great example.  Controller creep forward allows you to keep your amps in a reasonable range even in top gear.  Then when its time to back up, you can shoot back at 4 mph not just crawl in LL.  This alone cuts the final cleanup time in half.  With my old set up, the snow was melting on the hood from the resistors.  New set up no melting snow.

 

The throttle control allows you to get going with less whell spin and side slip.

 

Some controllers have a bypass contactor output option, but I don't think it would be needed with 300 amps.  The altrax is an order of magnitude more capable than my curtis 1204.  It handles the field weakening, regen, full reverse control, pc uploading and it can be customized by the user.  I just don't have the budget for it quite yet.

 

Rob, NH

Markus Lorch <mlorch vt edu> wrote:

> > > 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 
>
>
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