Posted by no spam on November 14, 2006, 8:56 pm
My biggest ignorance is in regenerative braking. How can a few seconds of
braking put any significant charge in a battery pack? My only thought was
if it was used to charge capacitors.
Now thinking about how it worked this morning got me wondering if an
electric school bus would work.
A couple of my thoughts on this. First let's forget any dangers associated
with mixing large batteries, kids and accidents.
Second, a school bus has a lot of space below the cab to store batteries.
Therefore no loss of passenger or cargo space.
Third, school busses have a lot of roof space for solar cells. Might they
be able to recharge themselves on most days with the 6-8 hours between the
morning run and the afternoon?
Fourth, busses do a lot of stop and go. This is where my ignorance of regen
braking comes in, would using it help in an electric bus.
Posted by Joe Fischer on November 14, 2006, 9:26 pm
It takes as much energy to stop a bus as it does
to get it going. Ultracapacitors can deliver power
faster to the motor than most batteries, and can be
charged faster without damage, and last 20 times
It takes no energy to keep moving, think of
a satellite in orbit, and a vehicle has wind resistance
and rolling friction, but most of the energy is used
There are lots of electric buses in operation, but
most are real expensive demonstration projects.
The weight of the batteries below the floor might
make it more difficult to turn over.
Still not enough space, and too expensive at this time,
but hopefully the price will come down.
All hybrid vehicles are electric vehicles, and they
get better mileage for two reasons, the power source can
be smaller and more efficient, and regenerative braking
can recapture some of the energy used to accelerate.
http://www.nyserda.org/Press_Releases/PressRelease.asp?i 3&d 06
Double click the link and see just one of many projects
getting under way.
Too bad most of them are just demo projects,
searching google for electric school bus will show many more.
Posted by Vaughn Simon on November 14, 2006, 11:37 pm
Nonsense. There are important uses of energy within the vehicle, plus you
grossly underestimate wind and rolling and mechanical resistance. We have been
over this ground before. If what you insist on saying were true, then there
would be no top limit on the speed of vehicles. They would just be able to
accelerate indefinitely until they either became airborne or the engine flew
apart from the RPMs.
That depends on the type of trip. I recently took a 500-mile trip in my
car and I found that my gas gauge sometimes dropped dramatically while I was
keeping a very constant speed with my cruise control (for hours at a time on the
Not necessarily so,( although all present mass-market hybrid autos have
electric as part of the drive system.) Hydraulics is another possible
competitive technology and flywheels have also been considered.
Posted by Joe Fischer on November 15, 2006, 12:04 am
On Tue, 14 Nov 2006 23:37:02 GMT, "Vaughn Simon"
Some, but there was a time when I had a gasoline
heater because the car did not come with a heater.
I don't under estimate it, up to 30 MPH wind
resistance isn't a big energy eater.
While any wheel is difficult for a human to turn
very fast, even a bicycle wheel, good bearings make a
big difference. I bought a cordless lawnmower from
B & D, and can't use it because it has plastic sleeve
bearings, and it is too much for an old man to push.
(am I the only one here with a lawnmower that
doesn't use fossil fuel?)
Yes, and the engineers want to keep the motor
connected to the wheels all the time.
Nonsense, air resistance is the limiting factor,
and it becomes substantial at about 40 MPH.
On that trip, regenerative braking wouldn't
make much difference.
But electric has the big advantages, the only problem
is the supply and price of copper.
I really would like to see all electric cars in the US
be compatible with household power, just like I only buy
12 volt cordless tools and lanterns.
Posted by Eeyore on November 15, 2006, 12:13 am
Joe Fischer wrote:
Try moving a surface the size of the front of a school bus @ 30 mph and you'll
retract that statement.