homegrown e-tractor

[Daystar Energy Services <daniel laser net>]

Recently posted to ev list.

I've been lurking around the archive for a while now and there's been
some discussion about electric lawn tractors lately. Some of you may be
interested in my attempt.

About a year ago I got my hands on a used 24v GE 1.5hp traction motor.
With lots of help from the good folks at EVA-DC, I set about converting
an old Toro riding mower. The first time I snapped the main contactor
on, the Toro stood up on its hind legs (with me and 4 trojan batteries
on it). After I changed my trousers, I went to Home Depot, bought a
harry homeowner welder and started redesigning my tractor from the
ground up. 

By May, I had a steel tube and fiberglass "electric lawn truck," with a
3 hp, 24v, series wound motor, curtis 1204 (275amp) controller, 300 amp
hr, 24v battery, insulated battery box, e-meter, 5 amp DC-DC converter
to power my AM-FM stereo and 12v power plug, a small (2' x 3') flatbed,
and a Trace 1500 watt modified sine wave inverter/charger. Except for a
couple of chain gears and axle bushings, the Toro is gone. Good
riddance, the people at Toro had dismissed my questions with a quick
"electric is impractical."

Top speed is between 10 and 12 mph. It takes about 35 to 40 amp hrs to
mow my 3/4 acre lawn by pulling a 3 head gang mower, frequently with one
or more kids riding on the flatbed just cause it's fun. I'm not happy
with the gang mower. It leaves uncut grass behind. I hope to retrofit a
rotary deck with a separate motor. Since I have 120v ac, finding a motor
should be easy.

I routinely trim the yard with my $30 corded weedwacker without getting
out of the seat. I have run my grinder, sawzall, 1/2" drill, dremel
tool, soldering iron, welder, 11.5 amp chain saw and electric guitar.

With a tow behind tool called a lawn sweep from the local hardware, I
can rake the yard (lots of big oak trees) in less than 2 hours while the
neighbors lean on their rakes with their mouths open. Just to see if it
could do it, I towed my wife's Dodge Caravan from 0 to 5 mph up a slight
incline, with her in it. The used batteries from the golf cart place
have yet to see 50% depth of discharge, even after six hours of cutting
up a couple of ancient apple trees with the chain saw then carrying the
fireplace logs and debris on a large utility trailer (8 or 10 trips
across the yard).

One of the best features is the stability. With 6 T875's centered
between the wheels just above the axle, sideways on a hill steep enough
to make the machine slip down the hill, all four wheels remain firmly on
the ground.

So far the bill has been about $3000 and untold hours. I have a list of
improvements that I want to try. I just got a snowplow blade and need to
find a way to hook it up. Steering and braking need to be reworked and
it looks like a kid's soapbox derby on steroids. But I would put this
impractical, backyard attempt up against any Toro.

Dan Lunceford