(ET) Converting a gasoline lawnmower

["John de Rivaz" <John deRivaz com>]

Anyone any suggestions on converting a gasoline lawnmower to electric
battery operation?

It is a 36" ride on and has a single engine driving a single blade and the
wheels through a simple forward and reverse gearbox.

Options are:

1. replace engine with a large electric motor

advantages: little mechanical change
disadvantages: more mechanical parts left to go wrong.

2. replace engine with two motors: one for forward/reverse movement, and 
one
or three for blades. (if three replace blades with smaller ones, of 
course).

Advantages: machine more reliable with less mechanics, could get low speed
DC motor for traction and remove gearbox or even put one motor on each of
the rear wheels and remove differential as well. Can control forward speed
independently so as to reduce cutting load for heavy work.

Disadvantages - much more work to install


Choice of motors.

DC motors -  good torque/speed characteristics from series motors for the
work, but expensive and difficult to get.

Auto alternators modified to work as motors (remove rectifier etc and drive
from 3 phase inverter). Negligible cost (from scrap yard) in comparison, 
but
efficacy of torque unknown.

100v AC 3 phase induction motors driven from inverter. Low cost, no
brushes/slip rings, but less efficient than synchronous motors (as above)

General comments/queries:

Anyone tried such conversion using sources of electric power other than
series DC brush type motors as discussed above, and did you meet with
success or failure?

The gasoline engines on these machines have ratings of several horsepower,
ie 7/10 kW in electric motor terms. Yet when running they spend most of the
time without giving full output. An electric motor rated at say 750 watts 
in
something like a drill is often called upon to give far more power in short
bursts. The motors discussed here for Elec-Traks seem relatively small in
comparison to gasoline engines - anyone know what is their rated power
continuous and peak?

--
Sincerely, John de Rivaz:      http://www.deRivaz.com :
http://www.AlecHarleyReeves.com
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