General Information

HEV Battery System

P1B76 High Voltage Relay Fault - General Information

Component Location





General Description

** What is the High Voltage Battery System?
The High Voltage Battery System consists of the Battery Management System Control Unit (BMS-ECU), Power Relay Assembly (PRA) and a Cooling Blower.
Each function is listed below :
- High Voltage Battery: Supplies electrical energy for acceleration and receives/stores electrical energy during deceleration.
- BMS ECU: Controls the High Voltage Battery by monitoring the voltage, current and temperature.
- PRA (Power relay assembly)consists of relays which link and cut high voltage, and finally, current sensor which monitors battery current. Those are an assembly in PRA.
- A safety plug : It can cut high voltage flowing as mechanically in order to protect technicians. And, there is a safety fuse in the safety plug that protect over current.
- Cooling Blower: Maintains proper High Voltage Battery temperature.
** The battery cell function and roles :
The High Voltage battery cell is the smallest unit of the High Voltage Battery pack.
The voltage of each cell is 3.75 V. The battery pack will attain 270 V by connecting all 72 cells in a series.
The BMS ECU monitors all of the 72 high-voltage cells, 5 battery temperature sensors, an ambient temperature sensor, a current sensor which checks the main battery and an auxiliary battery temperature sensor.
** The High-voltage battery specification is shown below :
Operating Voltage : for a battery pack : 200 - 310 V (for a battery cell: 2.75 - 4.3)
Operating temperature : -30 °C (-22 °F)~55 °C (131 °F)
Storage temperature : -40 °C (-40 °F)~65 °C (149 °F)
Operating Current : During charge (-)200A~ During discharge (+)200A.
Field action when High Voltage Battery discharges






DTC Description

The BMS ECU sets when the PRA could not control normal ON/OFF for 2 cycles, due to a welding of high voltage relay, (-) main relay, (+) main relay, or Precharge relay).

DTC Detecting Condition





Specification





Diagnostic Circuit Diagram






















Signal Waveform & Data




















Fig.1) SOC 45.% of high voltage battery - During KEY ON status, BMS Main Relay ON Status : YES
Fig.2) SOC 46.% of high voltage battery - During EV Mode status, the voltage of battery pack and Invert capacitor
Fig.3) SOC 46.% of high voltage battery - During EV dring mode, the voltage of battery pack and Invert capacitor
Fig.4) SOC 45.5.% of high voltage battery - During EV accelerating mode, the voltage of battery pack and Invert capacitor
Fig.5) After Key off and then Key on, the high voltage relay sequence operating waveform.