Hi,
Quote:
Originally Posted by dcb
there are many losses to consider:
engine to generator
generator to controller
controller to motor
generator to charger
charger to battery
battery to motor
transmission/wheels
whereas a small gasser can use
engine to transmission/wheels
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You've got some extra steps in there; and actually there are two ways to do serial hybrids. One is like the Volt and diesel/electric trains:
engine to generator
generator to controller
controller to motor
motor to reduction gears/wheels
The Volt has a battery that it uses first, and then if it is needed it goes into serial mode, with the ICE varying in speed to generate enough to power the electric motor. I don't think this is as good in a car as it is in a train, because a car has much more varied demands; whereas a train has so much mass, it only has two power modes (accelerate and cruise) and these are in "ultra slow motion" compared to a car.
The second uses a plug-in battery to start with and then the ICE recharges it, and then the ICE shuts off. So, the list is:
engine to generator
generator to charger
charger to battery
battery to motor
motor to reduction gears/wheels
And your ICE list is too short:
engine to clutch/torque converter
clutch/ torque converter to transmission
transmission to wheels
And the length of the list doesn't matter -- it's the efficiencies/losses for each.
A plug-in serial hybrid has a battery-only range, and for this mode it is
much better than the ICE: a gallon of gas = ~33kWh of electricity (IIRC) so, this means an MPGe of 100 is about the worst you can get in an electric car. From the
Plug In America FAQ:
The gas version of the RAV4 is almost
5X worse FE than the RAV4 EV.
The ICE in a serial hybrid by definition is going to be at peak efficiency ALL THE TIME. Also, by definition, it will be a much smaller, lighter, engine, and it will have smaller and lighter cooling system and fuel tank than an ICE powered car. Lets use the Mini as an example: 1.6L (I think?) vs the 250cc speaks for itself. The ICE Mini can probably get 40mpg (it is
EPA 24/33), so a 10 gallon tank goes 400 miles. The
Mini hybrid already gets 200-250 miles on it's batteries alone, and at 80mpg in charging mode, it only needs 2.5 gallons to get to 400 miles total.
So, the Mini Cooper gets 40mpg and uses 10 gallons of gas.
The Mini serial hybrid uses the electricity in it battery (probably about like the Tesla's?) of about 42kWh (80% of the 53kWh capacity) = 1.2727 gallons = 157MPGe for the first 200 miles, and then 80mpg and 2.5 gallons of gasoline for the second 200 miles. That is 118MPGe overall.
It's not even close.
And the Mini serial hybrid has 640HP and four wheel drive...