A 48 volt Freeway EV?

["Wilson, John A" <John.Wilson5@PSS.Boeing.com>]

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