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I think such a hybrid - a petrol-powered generator within an electric car - could have advantages under certain conditions. For instance the batteries could be relied upon solely in city environments or heavy traffic where pollution or noise is a concern or likely to have an impact on efficiency, and then the generator could be used to top up the battery at convenient moments.I don't think it's such a bad idea. The principle's not that different from the electric bikes you see people riding which rely on a combination of electrical and pedal power, with the battery receiving a top-up when the motor's not actively engaged.Chris
I think such a hybrid - a petrol-powered generator within an electric car - could have advantages under certain conditions. For instance the batteries could be relied upon solely in city environments or heavy traffic where pollution or noise is a concern
An internal-combustion-engine charging a battery which powers an electric motor will use more fossil fuel than an internal-combustion-engine only vehicle because of the conversion losses, (you'd only get a fraction of the energy from the battery of the petrol energy it took to charge it).
so that the differential gear (another energy waster) is not necessary.
Porsche also has a method to recover braking energy. The front wheels are driven by motors. During braking, they operate as generators to drive a motor that spins up a flywheel. During acceleration, the process is reversed.
The Toyota Prius does something a bit like that by using the electric motor in combination with a differential to produce a form of infinitely variable transmission. That allows the engine to run close to its "sweet spot" most of the time.
This has been around in one form or the other since at least the 1920's, and was used for buses.
Re. the Porsche thing (I think it's only for racing cars BTW) you need some sort of variable ratio transmission between the wheels and the flywheel, otherwise you'd have no control over the braking force, or the amount of acceleration. (Actually, the wheels would stop dead if the flywheel was stopped when you connected the wheels to the flywheel.)The motor/generators provide the "gearing" and necessary control.
Re. the (current) hybrids like the Prius, I think it's the other way around. They score during stop/go driving where you do a lot of braking and accelerating, but cruising on the open road, they don't have any advantage at all.
Of course the situation changes when you increase the size of the battery and you charge it from the grid.
Quote from: Geezer on 26/04/2010 18:33:04Re. the (current) hybrids like the Prius, I think it's the other way around. They score during stop/go driving where you do a lot of braking and accelerating, but cruising on the open road, they don't have any advantage at all.I thought that was what I was saying... mmmm, must Czech my English!
The charging load on the grid might not be that bad, particularly if you use smart meters that only supply energy during periods of low demand. Actually, the power suppliers might really like it because it allows then to get closer to a constant load.
I find it interesting that a question 4 years old still has not received anything other than a bunch of knee jerk reactions.
[...a hydraulics hybrid] that could carry 4 people, accelerate from 0-60 in less than 6 seconds, and got 75mpg. It used a 5hp engine running at three quarters throttle all the time to charge a hydraulic accumulator...
Because of conversion losses the internal combustion engine used to charge the batteries would either have to be more powerful than the one you took out of the car, or smaller and run for a longer period, say overnight when the vehicle was stationary