RE: (ET) RE: Alltrax DCX300 availability - Alltrax versus 4QD

["Markus Lorch" <mlorch vt edu>]

Tim,

you are right, its only rated at 1.2hp continuous. From my (little)
experience electric DC motors in this category are typically rated
to draw up to 5 times their rated amperage for short periods and
typically 20% more for the 1h rating. So for this motor it would
be something like 35A continuous, 40A for 1 hour, 175A max.

However, I have whitnessed my motor to draw in excess of 400A for
a few seconds, e.g. when I floor the peddle from a dead stop or 
when I drive up a an incline while I am in field weakening. The
current limiting feature on my working E20 turns field weakening
off pretty quickly and the current drops significantly.

So it sounds like a 120A controller is fine for most mowing 
but it may limit the performance of the E20 flagship
to what a smaller tractor could do as well. When I used
my E20 to grade my driveway (15 tons of 21A gravel) I 
did it in L and typically lost traction (even with chains)
on one wheel before the power meter showed in the red.   
For this type of work the missing differential lock is
the limiting factor IMO.


Markus

> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu 
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Tim
> Sent: Mittwoch, 26. Januar 2005 22:07
> To: elec-trak cosmos phy tufts edu
> Subject: Re: (ET) RE: Alltrax DCX300 availability - Alltrax versus 4QD
> 
> 
> My 4QD is analog.  I have not experienced the programming 
> issues or digital 
> gremlins of other controllers.  Also, I have not babied my 
> controller which 
> I have been using now for the last two Summers.
> 
> I see that the E20 drive motor is rated at 1.2HP continuous.  
> At 36vdc this 
> works out to 33.3 amps @75%efficiency.  With the wide range 
> in terrain that 
> I have, I cannot see where I would need 300 amps...maybe 
> someone else has 
> experienced otherwise.
> 
> Tim
> PS. If I do need more torque, I downshift the transmission.
> 
> ----- Original Message ----- 
> From: "John B Reinhard" <reinharj frontiernet net>
> To: <elec-trak cosmos phy tufts edu>
> Sent: Wednesday, January 26, 2005 10:24 AM
> Subject: Re: (ET) RE: Alltrax DCX300 availability - Alltrax versus 4QD
> 
> 
> >I think Alltrax makes a good product, and our market is tiny 
> volume, and
> > even their new 'retail' price is probably fair, all things 
> considered (for
> > instance: great warranty, compared to so many other products).
> > When you consider that the average software and hardware 
> enigineer earns
> > $75K and up, making a custom change to software in a 
> product to support
> > sales of a product in volumes of only a couple hundred units might 
> > actually
> > push the reatail cost of the unit.
> >
> > However, as I mentioned in a past email, since the 
> Elec-Traks are over 30
> > years old, and the Alltrax controller is potted and NOT 
> repairable, to me
> > the 2 year warranty seems quite limited.  I want to be able 
> to fix it
> > myself, after the warranty has expired.
> >
> > I read lots about the 4QD products - HUGE amounts of 
> information on their
> > website.  Positive info: the circuit boards are not potted.
> > But, the 4QD product cost more than the ORIGINAL price 
> Steve Richardson 
> > had
> > quoted online for the Alltrax product - and does NOT have 
> Field Weakening
> > (though this is probably not a problem for blowing snow).
> >
> > After shoveling twice a day for the last week, I was highly 
> motivated to
> > order an Alltrax Controller for one of my dead E-20's.
> >
> > But, after reading this thread regarding Alltrax new 
> pricing, and that 
> > Dave
> > (of 'Dave & Deb') has gone through 4 Alltrax controllers, I 
> am leaning 
> > back
> > toward 4QD, since I will be able to replace blown FET's or 
> whatever parts
> > myself (likely for LESS than the cost of just shipping the 
> controller back
> > to manufacturer for repair).
> >
> >
> >
> > ----- Original Message ----- 
> > From: "Markus Lorch" <mlorch vt edu>
> > To: "'David Roden (Akron OH USA)'" <roden ald net>;
> > <elec-trak cosmos phy tufts edu>
> > Sent: Tuesday, January 25, 2005 9:03 PM
> > Subject: RE: (ET) RE: Alltrax DCX300 availability
> >
> >
> >>
> >>
> >> >
> >> > >From what I understand, the ET model has additional 
> current sensing
> >> > circuitry for the field controller.  The ET's motor wants a
> >> > much lower field
> >> > current than a typical separately excited field golf car
> >> > motor, something like
> >> > one-tenth.
> >>
> >> Yes, I think I was wrong and they had to make some (minor, but
> >> manual) hardware modifications. Plus they also developed a 
> different 
> >> field
> >> map which Steve R. posted to the list a while ago. So the 
> ET version is
> >> basically a customized, low-volume product.
> >>
> >> I have gotten info on the (inexpensive) SPX controllers 
> that "look like"
> >> the DCP controllers we would need from Jeff @ Alltrax. It 
> turns out these
> >> were DCP controllers that had a problem with a bad 
> component in the field
> >> control circuit and thus were converted by Alltrax to standard 
> >> controllers
> >> for series wound or PM motors.
> >>
> >> Markus
> >>
> >>
> >> _______________________________________________
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> >> Elec-trak cosmos phy tufts edu
> >> https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
> >>
> >>
> >
> >
> >
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