Re: A 48 volt Freeway EV?

[Nathaniel Martin <nmartin@CellNet.com>]

Hello.

Amps=torque
voltage=speed

If you used a 100amp + controller with 48 volts, you would have kick-butt
performance for around 1000 RPMs, max. then the performance would drop off
rapidly. Unless you use gearing that will make around 1000 RPM =65 MPH, you
will have problems reaching highway speed.

If you are looking for low voltage, but good commuting cars, try 96 volts.
Even with small 400 amps controllers they can do highway speeds.

-Nathaniel Martin
nmartin@cellnet.com
nat@lumiere.net
'76 VW Rabbit "ZapRabbit" conversion to electric in progress


At 14:10 30/06/99 -0700, you wrote:
>Just another philosophical ramble on EV design... there's been a tendency
in EV design to go to higher and higher voltages in the battery pack. This
is great for performance, but also increases the problems with batteries.
The more cells, the more problems with equalization, cell failures...most
problems with hobbyist EVs are caused by the batteries.
>
>Perhaps the ultimate design for a day-to-day commuter (not a dragster) EV
would be to go to less voltage.  A 48 volt EV could use the massive Trojan
L16 batteries, which will last twice as long as the toughest golf cart
batteries, judging from the experience from off grid "Home Power"
applications. How about 40,000 miles on a set of batteries!  Fewer,
larger, and tougher cells makes for a highly reliable battery pack.  And
maintenance problems would be reduced as well. Watering the few cells in a
48 v pack would be easy,  and also infrequent because of the huge water
capacity of the cells.  Another benefit is that the shock hazard would be
almost eliminated at 48v.
>
>The obvious problem would be performance, if one's objective is to build a
real car, not a golf cart. Today's high power controllers can handle the
1000 amps required to give a 48 volt EV good acceleration and freeway
speed. However, a specially designed motor may also be needed , one with
but fewer but heaver windings and some sort of super-heavy duty commutator.
>
>Could a 48v freeway-capable EV be built?
>
>--Jay Wilson
>
>Seattle
>Jay  Wilson
>737 ECS Air Distribution & E/E Cooling
>425-237-0269  MS 70-04
>Fax 425-237-6149
>
>
>