Body Control Module (BCM)

BODY CONTROL MODULE (BCM)

The BCM communicates with the IBS to provide load shedding.

Load shedding is activated under the following conditions:

The engine must be running with an engine speed equal to or higher than 400 rpm for greater than 50 seconds.
The battery state of charge supplied by the IBS over the Local Interface Network (LIN) to the BCM must be less than or equal to 70%.
The battery voltage measured by the IBS and supplied to the BCM over the LIN bus must be less than or equal to 12.2 volts.

Any transition of the ignition state will rest all of the load shed output signals and therefor cancel load shedding operation.

To avoid electrical power system instability and to minimize driver's anxiety and concern, load shed operation is conducted in an orderly and progressive manner. It is categorized as seven levels and critical state, according to a net charge loss of the battery, which is summarized in the table below.

Levels	Battery Charge Reduction [Ah]	Devices to be affected
Level 1	5	Heated seat/Vented seat/Heated Wheel
Level 2	7.5	Heated seat/Vented seat/Heated Wheel
Level 3	10	Heated/cooled cupholders
Level 4	12.5	Rear defroster and heated mirrors
Level 5	15	HVAC system
Level 6	17.5	Power inverter system
Level 7	20	Audio and telematics system
Critical State	(SOC<=35%, and Battery voltage <=11.8V)
Or (SOC <= 70%, and Battery voltage <= 10.9V)

If the battery state of charge is equal to or less than 35%, and the battery voltage is equal to or less than 11.8 V, a "Battery Reached Critical State" output signal is broadcast. Another condition to set this output signal is that the battery voltage is less than or equal to 10.9 volts and the state of charge is less than or equal to 70%.

When the battery reaches critical state, only electrical loads essential to vehicle operation are allowed to be turned on. The following actions are recommended to be taken:

"Heated seats and heated steering wheel" are disabled for the duration of the ignition cycle
"Heated/cooled cupholders" are disabled for the duration of the ignition cycle
"Rear defroster and heated mirrors" time out in 30 seconds each time the customer turns them on, for the duration of the ignition cycle
"HVAC" systems is allowed only minimal loads for visibility requirements, for the duration of the ignition cycle
"Power inverter" is disabled for the duration of the ignition cycle
"Audio & Telematics Systems" will only allow minimal loads for communications and emergency requirements, for the duration of the ignition cycle.