[LINK] Electric vehicles and generation

[David Lochrin]

On Tue, 25 Jul 2006 15:24, Deus Ex Machina wrote:
> I remember people saying that by 2000 all cars will be tiny... I also remember them saying that by 2000 there will be no  more super cars.  this was in the 70s and 80s. individual transportation isnt about to shrink any time soon. its actually the large urban transit projects that will contine to decline.

   Ahhh - that explains why 4WD (aka SUV) vehicles are commanding such a high price now, and why both GMH and Ford in the U.S., both of whom had predicated much of their product line on large SUVs, have been so profitable in recent quarters.

On Tue, 25 Jul 2006 08:36, Tom Worthington wrote:

> Unlike the Wired fantasy, I saw a real battery powered car in an Indian village <http://www.tomw.net.au/blog/2006/01/indian-electric-car.html>.  These are produced in Bangalore and look like something Noddy would drive. But the company has sporty looking show model running Linux <http://www.tomw.net.au/technology/transport/reva.shtml>.

   I remember seeing battery-powered bread-delivery vans in Strathfield (Sydney) in my boyhood!  But of course they used lead-acid batteries and probably only went at about 20 miles per hour.

> Most of the major car companies have a little car in their range which could be retrofitted with an electric engine and batteries in this way.  For example [...]

   There's more to this technology than just fitting an electric motor.  I became interested in the Toyota Prius and may still buy one when my old Subaru retires, and I recommend studying what Toyota have done.

   The car has (from memory) a 53 Kw petrol engine and a 50 Kw AC motor, together with an alternator to charge the metal halide battery for regenerative braking.  Why A.C.?  D.C. motors are traditionally used for traction; a D.C. motor develops maximum torque at zero r.p.m. and zero torque at its maximum revs. but an A.C. motor only works well near its synchronous speed.  The key is the invertor.  Modern semiconductor technology allows the frequency of the invertor to be varied continuously so the A.C. motor r.p.m. can be varied to suit the speed of the vehicle, and Toyota can thus get the advantages of an A.C. motor without the synchronous-speed limitation.

   Regenerative braking is a key factor, especially around the city, as braking converts the kinetic energy of the car (and it's no lightweight either) to electrical energy in the battery.  It's speculated that one set of brake pads will last the life of the car.  Interestingly, Toyota claim to have never had to replace a battery under warranty.

   The Prius gets around 5 litres per 100 Km around town, but has a slightly higher consumption touring.

David