Re: (ET) Intro: Just bought an Elec-Trac

["Christopher Zach" <czach computer org>]

Golf carts then are the answer. Will find 6 somewhere :-) Can the front
mower do a rear discharge?

> Lastly, the charger takes a fair amount of power.  Max current is 14.5
Amps at 115V.  That's more than your 1400
> W inverter, but typical high current is 'only' about 8 Amps.  I don't
think your panels will charge the thing in a single
> day, and probably not in two.

Running a charger off the inverter isn't a great idea. If it's an induction
type charger (big transformer) then it would be wasting a *lot* of power
into heat. Also they tend to pull power off the peaks of the 60 cycle sine
wave, and the inverter is a modified square-wave (most power is at the .707
of the sine wave).

My actual plan is to charge straight off the panels using one to three
Solarex style regulators or (if I am going to go full 36v) a straight zener
diode/blocking diode to limit the voltage to the charge set level. The
panels (if I get another one) will put out a max of 15v at 7amps under
reasonable light conditions. Running that in series will give me a 7 amp
charge rate*4 hours a day. 125 amps a week, which should be enough to mow
the lawn.

I probably could have done this with a simple electric mower, but nooooo...
I have to get the 900lb tractor... I must be nuts.

Chris



> -----Original Message-----
> From: Christopher Zach [mailto:czach computer org]
> Sent: Sunday, January 06, 2002 8:22 PM
> To: elec-trak cosmos phy tufts edu
> Subject: (ET) Intro: Just bought an Elec-Trac
>
>
> Evening all!
>
> My name is Christopher Zach, and I just bought a new Elec-Trac tractor.
> Well, actually I just won the bid on Ebay, now I have to get up to NJ to
> pick the thing up :-)
>
> This is my first electric tractor, but not my first LV DC project. I am
> actually very intereted in solar power, and last year I took the plunge
and
> wired up my work shed (16 foot*12 foot) for 100% solar power. Basic 
> system
> has about 250 watts of panels, 24 volts DC, a 1400 watt inverter (old 
> UPS)
> and about 80ah worth of gel-cell batteries. Loads include the lights,
tools,
> whatever I need.
>
> The system has been working perfectly. Never run the batteries down, and
> always have enough solar to keep things peaked. However I have a 
> Craftsman
> lawn tractor, and I thought "You know, I could charge enough batteries to
> run an electric tractor...
>
> And the rest is history. This new one is an E20 with mower on the front.
I'm
> planning on putting new batteries in, and replacing the main charger with
a
> 12 volt input to the batteries (in parallel with diode blockers). Then I
can
> hook it to the 12 volt PTO on the shed and charge the batteries with a
solar
> charger.
>
> Well, in theory. Couple of quick questions to start:
>
> 1) Can one run 3 12 volt batteries, or does the Elec-Trak need 6 6volts?
> 2) Can one use standard golf cart batteries, or do I get the T105's?
> 3) Anyone live in NJ and want to help me get this thing onto a truck? :-)
> 4) Is it possible to put the mower on the center of the tractor instead 
> of
> out front?
> 5) Is it possible to put a clipping bagger on the tractor, or is that not
> going to work?
>
> Thanks; this is going to be interesting...
>
> Chris Zach
>
>