In message , at 17:54:57 on Mon, 19
Dec 2011, Richard J. remarked:
And in other news, it seems it's a perpetual motion machine in London:

"Transport for London (TfL) said the bus recharged its battery
using energy from its brakes, but on long journeys had to run on
diesel."

http://www.bbc.co.uk/news/uk-england-london-16244634

But I'm glad I diagnosed the problem correctly (there's some value in an
engineering degree after all!):

"However when the bus undertakes long, non-stopping motorway
journeys, such as its journey to Bedfordshire this morning, it
can lose charge and the driver is briefed to pull to the side of
the road to allow the battery to recharge."

London to Bedfordshire is not a "long" journey. And briefing the
driver to stop on a motorway is tantamount to inciting a criminal
offence. A vehicle that is not able to drive from London to Luton on a
motorway should not be allowed on a motorway at all.

I tend to agree that if as a well rounded engineer, familiar with the
foibles on novel solutions, I was asked to deliver that vehicle, I would
probably avoid motorways.

One wonders what the non-stop range is on a hot day with a full load
and the air conditioning at full stretch.

It doesn't matter if much of the time it's stuck at traffic lights,
during which time it can recharge.

But the same issues of "duty cycle" apply to all electric and most
hybrid vehicles. And let's not forget what happens in a couple of years
when the batteries are beginning to retain less of their charge.

I was quite disappointed to discover that the prototype hybrid double
deckers in Nottingham seemed configured to glide silently to a halt at
bus stops, then immediately start their engine at the exact point you'd
have preferred less fumes and noise for the passengers while boarding.

There's a bit more work required before this technology is optimised.
--
Roland Perry