Doctor Drivel wrote:

"The Natural Philosopher" wrote in message
...
Adrian wrote:
Roland Perry gurgled happily, sounding much like
they
were saying:

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

A very small step (for man or mankind....)

"The S-Class car, a 'mild' hybrid that will still draw most of
its power from petrol..."

Indeed.

But do Lithium Ion batteries provide the step forward that's being
alleged?

In my opinion, yes.

Not really. One litre of petrol provides 35MJ of energy, about 10kWh.
Even a small car will have a c.50 litre fuel tank, something the size
of an S-class nearer double that.

So that's 0.5-1MWh of energy on board. Wonder how big the battery
pack would have to be to replace that...? Wonder how long it'll take
to recharge...?


You forget that that energy is converted at less than 27% peak
efficiency, propably less than 20% average.: its nearer 95% with
battery electric, and with regenerative braking you get a little free
recharge.

Using super capacitors, 99% of all kinetic braking energy is recovered.

Seems unlikely given that the power of braking systems typically dwarfs
that of the motive systems in most cars. You will only be able to
recover at a rate proportional to the max output of the drive system.

Mechanical recovery into a flywheel might work.

--
Cheers,

John.

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