Re: (ET) Garden Pulling with the E20

["Markus" <ev lorch net>]

Hi Hump,

you're right in that it most likely was a combination of the
the batteries (basic flooded batteries) and the wiring. I had
noticed a significant power drop when changing from 3 100Ah
12V AGMs to the 6 215Ah flooded batteries. For the purpose 
of pulling I could go back to the AGMs.

About the motor: my E20 is not a shunt, its a compound wound
but I think this is what you meant to say as you are right in
that the series winding is relatively small compared to the
shunt windings that the motor has.  One can see that at a picture
I took once having one of them apart:
http://markus.lorch.net/et/motors/small/e20-motor-compound-field-windings.jp
g

I had long had the thoughts of using one of the ADC 6.7" motors
but I don't want to invest that kind of money. Maybe I run
accross an old fork lift truck motor one day.   

Markus 


> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu 
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of 
> Tim Humphrey
> Sent: Mittwoch, 31. Mai 2006 16:00
> To: elec-trak cosmos phy tufts edu
> Subject: Re: (ET) Garden Pulling with the E20
> 
> 
> Hmmmm...
> 
> I wonder if you were limited by the motor, or the batteries.
> 
> Did you do this with floodies?
> 
> You said that on the second pull you went into higher current 
> sooner. I would expect that if you didn't recharge
> between runs. Maybe some AGM's or NiCads would help.
> 
> You also said "I rememberd that the more a series wound DC 
> motor is slowed down, the more torque it produces (and amps
> it pulls, I started to smell the current shunt) ..."
> 
> That's true. But, the ET drive motor is not a series wound, 
> it is shunt, the small series winding is effectively
> useless. Now if you happen to have a snow-thrower or tiller 
> motor laying around......
> 
> But really I am thinking the problem is with sagging flooded 
> batteries and small wiring. I suspect that GE purposely
> used the small wire gauge that they did to limit current.
> 
> I was working on my Jr. Dragster just last week and noticed 
> that the wires going to my motor (stock GE E-15 motor and
> wires) were getting very hot compared to the rest of the 
> system. I replaced them with the same wire that I'm using for
> the rest of the system and those are now stone cold, with a 
> significant increase in starting torque. As a side note, I
> am removing the drive motor and replacing it with a 
> snowthrower motor. I hope to get more low end torque, and likewise
> a better holeshot.
> 
> 
> -- 
> Stay Charged!
> Hump
> "Ignorance is treatable, with a good prognosis. However, if 
> left untreated, it develops into Arrogance, which is often
> fatal. :-)" -- Lee Hart
> 
> Get your own FREE evgrin.com email address;
> send a request to ryan at evsourcecom
> 
> 
> >
> >
> > -----Original Message-----
> > From: elec-trak-bounces cosmos phy tufts edu
> > [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Markus
> > Sent: Wednesday, May 31, 2006 6:14 AM
> > To: 'Tim Humphrey'; elec-trak cosmos phy tufts edu
> > Subject: Re: (ET) Garden Pulling with the E20
> >
> > Hi Tim,
> >
> > yep, the tire was pretty good for this application.
> > I have the 23x10.5-12 agricultural tires. I bought them 
> last year, and I
> > remember they were pretty inexpensive compared to other 
> similar tires I
> > looked at. The brand was DURO, here is a picture.
> > http://www.tiresunlimited.com/images/duro/HF255.jpg
> > I got them somewhere on the web and had them mounted at a 
> local tire store.
> > Not sure if it was the company from the link above. Most of 
> the other
> > pullers had special tires, either the modified agricultural 
> tires (cut to
> > make them bite better) or the 26x12 size pitbull tires, 
> specially made for
> > garden pulling.
> > One comment about the tires: they were cheap and seem to 
> work fine, but they
> > stink - even while my tractors were stored outside you 
> could smell them from
> > quite a distance. It lasted about half a year, and by now 
> they have lost the
> > odor.
> >
> > However, with the tire above (and low air pressure) I had plenty of
> > traction, but no power left. I could've done a run in LL 
> and may have pulled
> > it farther but I didn't want to go that slowly.
> >
> > If I were pulling with the 15hp tractors I think I could 
> have had a good
> > chance to win. But compared to the 25hp "tuned" tractors 
> the E20 was a bit
> > weaker.
> > I've got a spare E15 motor sitting around and thought of 
> putting both motors
> > on it, but I don't want to break the gearbox or anything 
> else. So I think
> > the aim is to lighten the tractor and have my son drive it 
> in the small
> > 350kg/770lbs class.
> >
> > Markus
> 
> 
> 
> 
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