Just thinking out load here on the mpg front..
SO, anyone know how much juice an electric car uses for every given second?
Would a 6.5KVA generator be big enough to power a small EV?? Say something like the Imev or the Leaf??
There are some nice little 25hp V twin diesel engines knocking about that would very easily power a 6.5kva alternator..
Anyone think this setup may give somewhere near 150mpg, or more?
Does not compute...
If a piston engine requires 1 unit of energy to drive the car at a given speed.... the electric car still needs that 1 unit of energy.....
Converting Petrol energy into kinetic energy into electrical energy and back into kinetic energy again is really not efficient... you would need more
fuel not less!
Far better to cut out the middle man and attach the engine straight to the wheels....
[Edited on 11/12/12 by tegwin]
It only makes sense if you're using the generator to top up batteries which you would normally charge from domestic electrics.
Otherwise, as mentioned, you will simply be introducing an extra step into the process, thereby reducing energy. Arguably, a generator might run with
higher efficiency than a car engine working across a varied rev range, but there's not much in it.
One of those cases where.. do as the manufacturers do 
quote:
Originally posted by coozer
There are some nice little 25hp V twin diesel engines knocking about that would very easily power a 6.5kva alternator..
Anyone think this setup may give somewhere near 150mpg, or more?
As a range extender it could be really useful. Properly set up with the engine optimised for a constant speed the efficiency gained would more than
offset the conversion losses.
As an example here consider a desel electric locomotive.
However there are further gains to be made. Batteries loose efficiency when discharged quickly and by reducing the drain with a generator you are
effectively increacing the capacity of the battery.
Fantastic idea trouble is its already been thought of 
quote:
Originally posted by v8kid
As a range extender it could be really useful. Properly set up with the engine optimised for a constant speed the efficiency gained would more than offset the conversion losses.
As an example here consider a desel electric locomotive.
However there are further gains to be made. Batteries loose efficiency when discharged quickly and by reducing the drain with a generator you are effectively increacing the capacity of the battery.
Fantastic idea trouble is its already been thought of
quote:
Originally posted by MikeRJ
quote:
Originally posted by v8kid
As a range extender it could be really useful. Properly set up with the engine optimised for a constant speed the efficiency gained would more than offset the conversion losses.
As an example here consider a desel electric locomotive.
However there are further gains to be made. Batteries loose efficiency when discharged quickly and by reducing the drain with a generator you are effectively increacing the capacity of the battery.
Fantastic idea trouble is its already been thought of
Note that you also have to carry around an engine, generator, fuel tank, exhaust etc. which is why Lotus et al are developing super light weight range extender engines. Using some random diesel engine is likely to incur a significant weight penalty.
Locomotives use diesel/electric primarily for the torque characteristics of a motor (i.e. maximum torque at zero RPM) and the simplification of the transmission (no gearbox and propshafts required) rather than efficiency.
[Edited on 12/12/12 by MikeRJ]