648 Auto Electricity and Electronics
Copyright by Goodheart-Willcox Co., Inc.
Warning: To prevent electric shock, wait at
least fi ve minutes after removing the high-
voltage disconnect before working on the
high-voltage capacitors in the inverter circuit. It can
take up to fi ve minutes for any high-voltage
capacitors in the inverter circuit to discharge fully.
After you remove the high-voltage disconnect, remove
the high-voltage fuse and keep it in your pocket. This will
prevent anyone from accidentally reconnecting battery
pack power when circuits are being serviced.
Hybrid Battery Pack Service
Hybrid battery packs have a warranty from the
vehicle manufacturer. One automaker offers a full HV
battery pack replacement warranty for up to 8 years or
80,000 miles. Battery packs are very dependable and
seldom fail. Nevertheless, they can lose efficiency after
a period of extended service. The electrolyte and the
metal plates in the battery pack can be depleted after
years of operation.
Note: Remember that hybrid NiMH batteries
should not be stored for long periods. When
purchasing used battery packs from
recycling yards, fi nd out how long the battery pack
has been in storage. If left uncharged for over a year,
the battery plates and electrolyte will deteriorate and
it should not be purchased. Order a new battery pack
to avoid comebacks.
Battery Pack Recharging
With some hybrids, the internal combustion engine
will not start if the battery pack is drained or dead. This
occurs when someone accidentally leaves the headlights
or other electrical accessories turned on when the vehicle
is not running.
A hybrid battery charger uses a step-up transformer to
force high voltage back into the battery pack to re-energize
it. Follow the battery charger and vehicle manufacturer
instructions for safely connecting the charger cables to the
battery pack. See Figure 33-5. Procedures vary with make
and model hybrid. If the battery pack will not take a full
charge, it should be replaced.
Figure 33-5. A high-voltage battery charger is needed if the HV battery pack becomes drained and will no longer start the gas
engine. The battery charger is basically connected to ground and to the battery pack positive at special service connectors. Then
the charger is turned on to force electrical energy back into the battery pack. After charging, test-drive the vehicle to make sure the
motor-generator will charge the battery. (Toyota)
HV Battery
Auxiliary
Battery
Battery ECU
Connector
Frame
Wire
Battery
Charger
Frame
Wire