The Natural Philosopher wrote:
Rod wrote:
Adrian wrote:
Rod gurgled happily, sounding much like they
were
saying:

http://www.ft.com/cms/s/0/7f2f081e-2...077b07658.html

But how do you heat an electric car? Not much fun using a totally
unheated behicle in the winter. Even keeping the screens clear
becomes a
bit of a problem.

shrug Easy. Instead of a water-to-air matrix, use an electric
element. The actual air distribution and circulation is electric
anyway. For aircon, the compressor is electrically driven, as many
power steering pumps currently are.

Some earlier electric cars had petrol burners to warm the interior. Is
that included in the fuel efficiency claimed?

Just as it isn't in modern common-rail diesels which are so heat
efficient that many of those have an additional diesel-fuelled heater.

As I said to begin with, early electric cars sometimes had a petrol
burner because the designers felt it unwise to use the stored electric
power for heating purposes. Given very low weight, low cost energy
storage perhaps the balance shifts. But most particularly, I would
like to know that the heating energy usage has been fully factored in
- for cold winters - when fuel consumptions are compared. It could
make a huge difference compared to a cool summer.

Well all I know is that it takes less than 500W to heat our smallest
bathroom - about the size of a car - in the coldest weather. That is
slightly less than a brake horsepower.

I am not 100% sure of the figures, but a small car on cruise at 40-50mph
uses at least 10bhp i would think. So the power to heat is not dominant
at the very least, and may well be very small, or if you can tap into
the - say - 10% heatloss of the cars power train, essentially free anyway.

I would expect the electric car would be made from fairly thin metal to
save wight, with foam insulation inside..major heatloss (and heat gain)
would be via the windows. Double glazing, or even reducing windows and
using rear view CCTV for visibility, would actually be an advantage.


But a small bathroom is probably a) much better insulated b) not subject
to high winds on all six sides c) not allowed to drop to, say, minus 10
C between uses.

The cooling effect of, say, driving at 60 mph into a 40 mph headwind
with outside air temperature at around minus 10 is considerable. (No - I
don't have figures but even with an inefficient petrol engined vehicle
pushing out lots of 'waste' heat it can get pretty cold inside.) Even
if passengers wrap up (in their woolly clothes) the screens still need
heating to keep clear in freezing rain, snow, etc.

Indeed, insulation may save the day. CCTV is a really good idea
(assuming it is done well). But please at least ensure these issues are
factored in.

--
Rod

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Although common it frequently goes undiagnosed.
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