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Speaker 1: Welcome to Brainstuff from how stuff works dot com where
Speaker 1: smart Happens. Hi. I'm Marshall Brain with today's question, how
Speaker 1: does a hybrid car work? We're all familiar with gasoline
Speaker 1: powered cars, and most people have heard about our scene
Speaker 1: electric cars. A hybrid car is a combination of the two.
Speaker 1: Hybrid vehicle contains both a gasoline engine and an electric
Speaker 1: motor in an attempt to get the best of both worlds.
Speaker 1: The best way to understand the advantages of a hybrid
Speaker 1: vehicle is to think about a car traveling down a
Speaker 1: highway at the postage speed on level ground. In this case,
Speaker 1: the engine is doing three things. First, it's overcoming rolling
Speaker 1: resistance in the drivetrain. Second, it's overcoming air resistance, and
Speaker 1: third it's powering accessories like the alternator and the air conditioner.
Speaker 1: The engine might need to produce no more than twenty
Speaker 1: horse power to carry this load. The reason why cars
Speaker 1: have a hundred or two hundred or three hundred horsepower
Speaker 1: engines is to handle acceleration from a standing stop, as
Speaker 1: well as for passing and hill climbing. We only use
Speaker 1: the maximum horsepower rating for one percent of the driving time.
Speaker 1: The rest of the time we are carrying around the
Speaker 1: weight and friction of that much larger engine, and that
Speaker 1: wastes a lot of energy. In a pure hybrid vehicle,
Speaker 1: you have a complete electric car. It includes an electric
Speaker 1: motor to provide power to the wheels, as well as
Speaker 1: batteries to supply the motor with electricity. Then you have
Speaker 1: a completely separate gasoline engine powering a generator. The engine
Speaker 1: is small, perhaps only twenty horsepower, and it's designed to
Speaker 1: run it just one speed for maximum efficiency. The purpose
Speaker 1: of this small, efficient engine is to provide enough power
Speaker 1: for the car at its cruising speed. During times of acceleration,
Speaker 1: the batteries provide the extra power necessary. When the car
Speaker 1: is decelerating or standing still, the batteries recharge. This sort
Speaker 1: of hybrid car is essentially an electric car with a
Speaker 1: built in recharger for longer range. The advantage is that
Speaker 1: the small, efficient gasoline engine gets great mileage. The only
Speaker 1: problem with this traditional hybrid car is the weight. The
Speaker 1: car has to carry the weight of the electric motor,
Speaker 1: the generator, the gasoline engine, and the batteries. You don't
Speaker 1: need as many batteries as a pure electric car, so
Speaker 1: that saves some weight, but a full size electric motor
Speaker 1: plus a ten kilowatt generator can weigh several hundred pounds.
Speaker 1: Most hybrid vehicles, therefore, try to strike a compromise. They
Speaker 1: use a larger gasoline engine that's connected directly to the
Speaker 1: drive train, along with a smaller electric motor attached to
Speaker 1: the engine or the transmission. The gasoline engine provides most
Speaker 1: of the car's power, with the electric motor adding extra
Speaker 1: power is needed for acceleration. Because the electric motor can
Speaker 1: double as a generator during breaking and only has to
Speaker 1: run part of the time, it can be extremely light.
Speaker 1: The disadvantage of this approach is that the gasoline engine
Speaker 1: must run at varying speeds, which reduces its efficiency. For
Speaker 1: more on this and thousands of other topics, is It
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