How Does the Toyota Prius Charging System Work?

by Alexander Eliot
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With its hybrid engine technology, the Toyota Prius has grown into the epitome of environmentally friendly cars. Using an electric motor in conjunction with a conventional gasoline engine, the Prius boasts high fuel economy and low carbon emissions, well beyond what is attainable with most conventionally powered vehicles. To maximize gas mileage while keeping emissions as low as possible, the Prius features an advanced charging system that allows the battery to tap into power from the Prius' gasoline engine while using kinetic force from braking to generate additional electricity.

Power Train Setup

The term "hybrid" refers to the combined use of an internal combustion engine and electric motor. The first and second generation Toyota Prius were equipped with a 1.5-liter gasoline engine that produced 70 and 78 horsepower, respectively, while the third generation Prius featured a slightly larger 1.8-liter engine that churns out 98 horsepower. An electric motor is linked to the gasoline engine via a power-splitting device, and is connected to a traction motor connected to the front axle.

Conventional Power

Under heavy acceleration, the Prius utilizes power from the gasoline engine assisted by the electric motor. Under less-demanding driving scenarios, a portion of the gasoline engine's power is converted into energy by the electric motor and stored in a nickel metal hydride battery pack, located in the rear hatch area. When under light loads, the Prius maximizes fuel economy by shutting off the gasoline engine and powering the vehicle purely with the electric motor, using energy stored in the battery pack.

Regenerative Braking

The Toyota Prius further maximizes fuel economy by using some of the energy exerted under braking to partially recharge the battery pack – a feature known as regenerative braking. When in motion, a vehicle possesses kinetic energy due to its mass. It's the job of the brakes to create friction in order to reduce the kinetic energy, which in turn slows the vehicle. On the Prius, the traction motor is used as an electric generator by taking on some of the braking duty. Since the axle requires force to drive the traction motor, it is able to slow the vehicle while recovering some of the kinetic energy that is generally dispersed as heat when braking.

Prius Plug-In 2012

For 2012, Toyota added a plug-in Prius model to its lineup. In addition to the hybrid gasoline-electric setup, the Prius Plug-In features the capability of charging from a standard 120-volt household outlet with a dedicated 15-amp circuit. The Prius Plug-In requires three hours for a full charge, which allows for a range of up to 15 miles and speeds up to 62 mph. When the charge runs out, the Prius Plug-In automatically switches over to its hybrid power train.

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