Re: EV's of course

[David Roden <roden@wksu.org>]

> What I need is help figuring out how many batteries and what size.
> What will it weigh? What motor to use? I want it to do city speed
> limit or faster:) for at least 40 miles before slowing down.

Didn't Cushman build an electric version of this machine?  If so, that might
be the easiest, most direct place to start.

If not, there are a couple possible directions, which depend on your budget.
For an inexpensive conversion, a small series motor like the Advanced DC
K91-4003 would work fine.  

You have modest performance goals, so you probably will want to go with
flooded batteries for lowest cost per mile.  With a transmission you could
go for 48 volts, but without one I'd use 60 or 72 volts from 10 or 12 golf
car batteries.  If you can't find enough room in the chassis for that many
6-volt batteries, use 8-volt golf car batteries from US Battery or Trojan.
Stay away from the 12-volt flooded batteries; they usually have short lives
in EV use.

You can get a remanufactured golf car controller in the voltage you need
from Golf Tech Industries.  Their webpage seems to be down now, but you
might try 

     http://www.golftechind.com/products.htm

for more information.  There are many dealers who sell new controllers.

Total cost for motor, controller, and batteries should be around $2,000 or
so, even with a new controller.  Then there will be additional costs for
machine shop work, a 12-volt power source, and so on.

If you have deep pockets and you'd like to build a higher-tech vehicle, you
might look into the smaller AC induction motors and controllers from
Solectria.  Their smallest controller, the AC-220 (20 kw), and the GT-20T
motor, would be just fine for this application.  The next size up costs only
a few hundred more (at these prices, who'd notice <grin>) and would probably
give you more power than you'd ever need for in-town use in such a light
vehicle.

It would require higher voltage than the DC system (108 volts minimum), so
you would probably want to go with 12 Optima Yellow Tops (144 volts) or
perhaps 10 larger Hawker Genesis batteries, to get reasonable life and good
range.  

This version of the project would probably cost nearly $9,000 just for the
motor, controller and batteries -- much more expensive than DC, but you
would gain seamless regenerative braking (perhaps worthwhile if the
vehicle's mechanical brakes are feeble) and perhaps somewhat higher
reliability.

Either way, it sounds like a fun project.  Keep us posted!


David Roden
Akron OH USA