Battery System Description
For locations of each component on vehicle, refer to Component Location Index .
The high voltage battery uses a Li-ion (lithium ion) battery. A Li-ion battery is lightweight, compact in size and has a long lifespan. The high voltage battery charging is provided by the electric power from the generator motor or the traction motor via inverter in the PCU.
Control
The high voltage battery is equipped with multiple sensors that send information to the battery condition monitor module.
Battery Output Control
The amount of power that can be removed from or put into a battery will vary depending on various conditions such as the temperature of the battery and the health of the battery. If more power is moved into or out of the battery than the battery can safely handle, the battery life will be shortened or in a worse case situation, the battery could be damaged severely (thermal runaway, fluid leakage, etc.). To prevent damage and maximize the battery capacity over the life of the battery, the battery charging and discharging is controlled by the battery condition monitor module. The battery condition monitor module uses inputs from the battery module temperature sensors, the battery current sensor, and the state of charge (SOC) calculated by the battery condition monitor module to control the power into and out of the battery. The battery condition monitor module uses the above information as well as the demand for power to determine the optimum power of the battery at all times.
SOC Management Control
To prevent deterioration of the battery, the SOC is controlled by the battery condition monitor module. If necessary, the battery condition monitor module will limit the power output if the SOC should reach unacceptable levels.
| HDS Parameter | Normal Control Area |
|---|---|
| SOC | 0 - 100 % |
| Motor Power Save (Affected by HV Battery SOC) | No/Restricted |
Temperature Management Control
To prevent damage to the battery in extreme high or low temperatures, the battery condition monitor module may limit the battery power. The battery condition monitor module also controls the operation of the high voltage battery module fan.
| HDS Parameter | Normal Control Area |
|---|---|
| HV Battery Module Temperature Sensor 1 | Depending on battery temperature |
| HV Battery Module Temperature Sensor 2 | Depending on battery temperature |
| HV Battery Module Temperature Sensor 3 | Depending on battery temperature |
| HV Battery Module Temperature Sensor 4 | Depending on battery temperature |
High Voltage Circuit Shut-Off Control at the time of Collision Detection
When the SRS unit detects a collision signal (front collision, side collision, rear collision), the battery condition monitor module stores the DTC according to a signal from the SRS unit, and the high voltage circuit is cut off by switching the contactors to OFF. At this time, the POWER SYSTEM indicator, the 12 volt charging system indicator, and the SRS indicator come on, and the READY indicator goes out. The collision shut-off control is cancelled by using the HDS to clear the DTC in the battery condition monitor module.
Components
Junction Board/Subjunction Board
The junction board and the subjunction board isolate the high voltage battery, and distribute power to other high voltage systems. The junction board and subjunction board are installed in the IPU. The main fuse, the contactors, and the battery current sensor are located on the junction board.
Contactor
The high voltage contactor and the bypass contactor are arranged on the positive pole side of the battery pack, while the high voltage sub contactor is arranged on the negative pole side. These contactors are controlled by the battery condition monitor module and perform connection and disconnection of the high voltage circuit. When the contactor connects to the positive pole side, the bypass contactor switches to ON before the high voltage contactor is turned on connecting the high voltage circuit via a pre-charge resistance limits the rush current until the capacitor is charged; this serves to protect the system. Several large capacitors are located in the PCU. When the system starts up, these capacitors are discharged and if the battery were connected by the high voltage contactor a very large and damaging current would flow. This is referred to as inrush current. This current could damage various components but would cause arcing on the high voltage contactor. To prevent a large inrush current, a bypass contactor is switches to ON first at start up. This connects the high voltage battery to the various capacitors thru a resistor limiting the current and allowing the capacitors to charge. In a very short time the capacitors are charged, then the high voltage contactor switches to ON and the bypass contactor switches to OFF.
Battery Current Sensor
The battery current sensor detects the input and output current of the high voltage battery. The input/output current detected by the sensor is sent to the battery condition monitor module; it is used for calculating the remaining capacity of the state of charge (SOC).
Service Plug
The service plug is installed in the high voltage circuit of the high voltage battery and in the contactor control circuit. By removing this plug, the high voltage circuit and the contactor control circuit can be interrupted when the electric powertrain system or the parts around it have to be inspected or serviced. This ensures that safe inspection and servicing work can be done. When removing the service plug, make sure you have read the electric powertrain service precautions .
Special Bolt
A high tension, truss head type special bolt is used on high voltage circuit connection points to properly secure the connection and reduce the possibility of becoming loose. Do not replace these bolts with any other type.
High Voltage Battery Module Fan
When the electric powertrain system repeats the charging and discharging cycles, the battery pack become hot. To dissipate this heat - and to maintain the high voltage battery performance and protection of the system - a high voltage battery module fan is installed in the IPU. The high voltage battery module fan uses a fan motor control circuit and a speed sensor built in, and the battery condition monitor module controls the high voltage battery module fan so that the high voltage battery temperature is kept at a suitable level. The cooling air intake is located at right side of the rear seat, and it passes through the battery pack, then discharged to the luggage compartment.
Battery Power Cable
The battery power cable located between the IPU and the PCU is protected by a corrugated tube and an orange aluminum pipe against external damages, and is secured with a clamp under the floor. Inside the pipe are the high voltage cable, the 12 volt power supply cable from the DC-DC convertor, and the electric A/C compressor cable.