512 Section 5 Electrical and Electronic Systems Technology
Hybrid Starting System Operation
In a hybrid, the internal combustion engine runs
only when it is needed. The engine will be shut off
when braking, coasting, going downhill, or when the
vehicle is stopped. It is wasteful to run the internal
combustion engine when its power is not needed.
The hybrid control module monitors operating
conditions to determine when the internal combus-
tion engine should be started. If the hybrid control
module determines that the engine should be started,
it signals the HV power control module to start the
engine for propulsion and HV battery recharging.
It also signals the engine control module to provide
fuel and spark for engine starting and running. The
HV power control module then applies voltage to
the stator windings of the motor-generator to rotate
the armature and the engine crankshaft.
Common reasons for starting the engine include a
need to recharge the HV battery, a demand for more
power during acceleration, high-speed operation, or
an engine that has not been started for an extended
period of time (too much driving in all electric mode).
Green Tech
Recycling Batteries
Today’s lead-acid batteries typically contain a large
percentage of recycled materials. This is because
lead-acid batteries are recycled and some of their
materials can be reused. Less new material needs
to go into a new battery. Several automotive shops
collect and send dead batteries to off-site recycling
facilities. Used batteries can be stored for up to a year
before being recycled. It is best to store used lead-
acid batteries inside, away from the drainage system
and any source of ignition. Cracked batteries should
be contained, and any spills from a battery crack
should be cleaned up as quickly as possible.
Summary
❚ A 12-volt starting system uses battery power and
an electric motor to turn the engine crankshaft for
engine starting.
❚ A starting motor converts electrical energy from
the battery into mechanical or rotating energy to
crank the engine.
❚ A commutator serves as a sliding electrical con-
nection between the motor windings and the
brushes.
❚ A fi eld winding is a stationary set of windings
(insulated wire wrapped in circular shape).
❚ A permanent-magnet starter uses special high-
strength magnets in place of conventional fi eld
windings.
❚ A starter pinion gear is a small gear on the arma-
ture shaft that engages a large ring gear on the
engine fl ywheel.
❚ A starter overrunning clutch locks the pinion gear
in one direction and releases it in the other.
❚ A starter solenoid is a high-current relay that
makes an electrical connection between the bat-
tery and starting motor.
❚ A reduction starter is sometimes used to further
increase the rotating force applied to the engine
fl ywheel.
❚ A neutral safety switch prevents the engine from
cranking unless the shift selector is in neutral or
park.
❚ A 12-volt starter relay uses a small current fl ow
from the start switch to control a slightly larger
current fl ow to the starter solenoid.
❚ An ECM-controlled starting circuit automatically
energizes and de-energizes the 12-volt starting
motor as soon as the engine sensors detect fuel
combustion and the resulting rapid increase in
crankshaft rpms (speed sensor signal).
❚ A hybrid starting system includes a motor-gen-
erator, HV power cables, hybrid control module,
HV power control module, and engine control
module (ECM).
❚ The HV power control module converts dc into
three-phase ac for the motor-generator. If a vehi-
cle does not have a separate hybrid control mod-
ule, the HV power control module determines
when the engine should be started and sends
three-phase ac to operate the motor-generator for
engine startup.