The Natural Philosopher wrote:
On Wed, 30 Nov 2005 01:19:06 +0000 (GMT), Dave Plowman (News) wrote
In article ws.net,
Doctor Drivel wrote:

Until you want to heat the car, and have more than two people in it.

Electric motors give off heat. This can be harnessed.

How much heat does the average car heater give out on full?
How much insulation do you have on a weight saving electric design?
When will you think these things through rather than blindly accepting
wild claims in ads?

Well I'll amswer what Drivel can't.

At say 250Wh per mile and an average speed of 60miles an hour, the actual
power input is 15KW. Or 20bhp. Which sounds about right.At 90% efficiency
you are losing 1.5KW. More than enough to heat the car IF you could get the
heat from the motors to the car interior.

Its possible to wind the motirs not with wire, but with small bore copper
tube and pass coolant thriugh them, but its complex and makes the motors
larger and higher resistance (less efficient).

So its feasiable, but I don;t think its necessarily practicable. I think it
might increase the motor losses anway - its probably better to simply take
an electrical heat pump and use it to heat or cool the interior depending
on whether ambient is above or below desired heat levels.

Becasue motor heat output is not that huge, and falls away to nowt at
'idle'

or perhaps add a shroud over 2 motors, and air duct from motor to
interior. Forward movement then causes warm to be blown into the
interior. A backup fan is needed during short stops, and electric
heating for longer stops. All easy to control automatically.


NT