High Voltage Safety; High Voltage Safety System - Lexus ES300h Vehicle Dismantling Manual

High Voltage Safety

The HV battery pack powers the high voltage electrical system with DC electricity. Positive
and negative orange colored high voltage power cables are routed from the battery pack, under
the vehicle floor pan, to the inverter/converter. The inverter/converter contains a circuit that
boosts the HV battery voltage from 244.8 to 650 Volts DC. The inverter/converter creates
3-phase AC to power the motor. Power cables are routed from the inverter/converter to each
high voltage motor (electric motor, electric generator, and A/C compressor). The following
systems are intended to help keep occupants in the vehicle and emergency responders safe from
high voltage electricity:

High Voltage Safety System


A high voltage fuse * provides short circuit protection in the HV battery pack.

Positive and negative high voltage power cables * connected to the HV battery pack are
controlled by 12 Volt normally open relays *. When the vehicle is shut off, the relays
stop electrical flow from leaving the HV battery pack.
WARNING:
・ The high voltage system may remain powered for up to 10
minutes after the vehicle is shut off or disabled. To prevent
serious injury or death from severe burns or electric shock,
avoid touching, cutting, or breaching any orange high
voltage power cable or high voltage component.

Both positive and negative power cables * are insulated from the metal body. High
voltage electricity flows through these cables and not through the metal vehicle body. The
metal vehicle body is safe to touch because it is insulated from the high voltage
components.

A ground fault monitor in the hybrid vehicle computer * continuously monitors for high
voltage leakage to the metal chassis while the vehicle is running. If a malfunction is
detected, the hybrid vehicle computer * will illuminate the master warning light
the instrument cluster and a message indicating that the hybrid system is malfunctioning
will be displayed on the multi-information display.

The HV battery pack relays will automatically open to stop electrical flow in a collision
sufficient to activate the SRS.
*Numbers apply to the illustration on the following page.
11
in