Toyota Prius Manual page 44

About the Prius Plug-in Hybrid (2012 Model)
The Prius Plug-in hybrid contains a gasoline engine, an electric motor,
and a newly developed large capacity Li-ion battery. It is the first
Toyota hybrid that allows the HV battery to be plugged-in and charged
by an external power source. Two power sources are stored on board
the vehicle:
3. Gasoline stored in the fuel tank for the gasoline engine.
4. Electricity stored in a large capacity externally chargeable high
voltage Hybrid Vehicle (HV) battery assembly for the electric
motor.
Depending on the driving conditions, one or both sources are used to
power the vehicle. The following illustration demonstrates how the
Prius Plug-in hybrid operates in various driving modes.
Plug-in EV (Electric Vehicle) Mode:
Utilizing the charge cable assembly connected to a 120 Volt outlet,
the vehicle's HV battery can be charged within 3 hours.
When the HV battery is sufficiently charged, the vehicle will
basically run on the power of the electric motor for approximately
11 miles.
If the vehicle exceeds approximately 60 mph (100 km/h) or
accelerates suddenly when traveling in EV mode, the gasoline
engine and electric motor work together to power the vehicle.
Plug-in Charging Normal Driving
Plug-in charging
Electricity
EV Mode
Starting
Hard Acceleration
Exceeds
Approximately 60 mph (100 km/h)
Electricity and gasoline Electricity
When the HV battery is discharged the vehicle operates in Hybrid Vehicle
mode
HV (Hybrid Vehicle) Mode:
During light acceleration at low speeds, the vehicle is powered by
the electric motor. The gasoline engine is shut off.
During normal driving, the vehicle is powered mainly by the
gasoline engine. The gasoline engine also powers the generator to
recharge the HV battery assembly and to drive the motor.
During full acceleration, such as climbing a hill, both the gasoline
engine and the electric motor power the vehicle.
During deceleration, such as when braking, the vehicle regenerates
the kinetic energy from the front wheels to produce electricity that
recharges the HV battery assembly.
While the vehicle is stopped, the gasoline engine and electric motor
are off, however the vehicle remains on and operational.
Normal Driving Acceleration
Electricity and gasoline Electricity and gasoline
(Additional electricity
extracted from batteries)
HV (Hybrid Vehicle) Mode
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Deceleration Stopping
Engine automatically stopped
Charging batteries