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Andy Champ[_2_] Andy Champ[_2_] is offline
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Default More on electric cars.

On 19/09/2012 00:42, The Natural Philosopher wrote:

yes.

Not cheap - Neodymium magnets and enough silicon iron in the stator..

http://www.hobbyking.com/hobbycity/s...ner_Motor.html


is running at about 5bhp per kg.you probably need about 20bhp per wheel
for a small car (80bhp AWD). Which is 4kg per wheel. That's probably
about the same as an axle hub and CV joint.


Hmm. I'd like a bit more power than that, remember I have to hoik a
battery pack around. 10kg per wheel seems closer. And the brakes need
to be outboard too, if you don't have shafts. (you still need brakes, if
only for emergencies)

Its definitely better weight wise to use a motor per wheel and dump the
differential as well.

With you there.

The problem with an inboard motor is you need the CV joints (or a
dreadful swinging axle) as well. Those add weight and cost.


I think you only need the outboard joint.

Plus you get better packaging with in wheel motors.

I'll take your word for that.

Biggest problem is you probably can't gear it - except with more in
wheel weight like an epicylic box. So it needs a LOT of poles to get the
actual torque you need. AND you need flexible and pretty substantial
cables as well

Equally true for inboard!

But overall I think that the best way to package a leccy car from a
'blank sheet' is battery under the floor to keep weight down low and
extending right into the axle regions, and a motor on each wheel.
The battery is far and away the heaviest thing so you want it low and in
the car model. The means you probably don't want transmission there at all.

Bernie Ecclestone has announce a 'Formula E' series for all electric
racing. It will be fascinating to follow. And see what they end up with
by way of battery swapping and getting performance out of the cars.

http://www.bbc.co.uk/news/business-19402383


Thanks for the data.

Andy