(ET) Recent thread on rewiring

["Gary H. Lucas" <gary lucas verizon net>]

Hello,
This is my first post, hope I did this right.  I've been following the mail
list.  I have an Electrak, but it
would be hard to say which one.  I bought it from my best friend's wife a
couple of years after he died.  I had been keeping it running for him for
nearly 20 years, as I was an industrial electrician.  It has mower motors
and
a drive motor from different models, and all new paint, wiring, etc.  It is
also my second one.  I had an E-15 that I got from another electrician, who
couldn't keep it running!  It was in very poor shape as it began life 
mowing
at an apartment complex.  My wife loved it though.  At one point the board
was getting really bad.  She came home and found me sitting on the tractor
with the board and a bundle of sitting on the ground.  She wanted to know
what I had done to her tractor.  I said, "Well if it was human you'd
probably call it a lobotomy.  It's no longer smart, but it still 
functions!"
It lasted a few more years until it was just consumed by rust and major
problems.

The talk about building new boards I find interesting, as I see no need to
bother.  I've been using Curtis PMC controllers in various battery powered
machines for at least 16 years.  So I put one in my Electrak.  As I recall
it cost me about $230 about 8 years ago, with a footpedal potentiometer.  
It
has built it safety features, like the throttle pot must be returned to 0
before it will move when power is first applied.  My tractor had the manual
speed lever with steps on the dashboard, and reverse was on the same lever.
I reused that assembly with only two microswitches for forward and reverse.
The contactor drops out when changing direction so that you can't slam from
forward to reverse, it just stops.  I installed new contactors and expect
them to last almost forever.  They no longer switch under load, so there is
no arcing.  However if I did it again I would use the Curtis Albright
reversing contactor, with two coils.  It is easy to wire, compact, rugged
and even rebuildable.

The Curtis controller acts like a transformer.  At half speed, which is 
half
voltage, the batteries only see half the current too.  So the batteries run
much longer.  Operation is extremely smooth too.  One possibility for
operating 12 volt accessories from 36 volts is to use a small Curtis
controller as a converter to make 12 volts from 36 volts, thus putting the
load across the entire battery bank.  Your accessories would run well right
down to dead batteries as you could keep the voltage constant.

I've also given the though to building a new Electrak.  I'd use only 4
batteries, a light weight aluminum garden tractor transmission and aluminum
frame.  Two batteries under the seat and two up front.  The batteries go in
off the shelf roto-molded plastic tanks (I work in waste treatment and use
them all the time)  that can hold concentrated battery acid without damage,
so no frame corrosion.  A plastic lid goes on top and the controls and
headlights mount under an aluminum cover over the front batteries.  The 
seat
is mounted on the rear battery box cover, with the usual switch.  I can cut
the two rear fenders from a single round poly tank, so they'll be
unbreakable and non rusting too.  I figure it won't be cheaper than a gas
garden tractor I can buy, but it'll last the rest of my life!

Gary H. Lucas