Onboard network control unit task - GF54.21-P-4118-01R

The onboard network control unit (N82/1)  has the following tasks

• Controls the battery separation relay (K57) 
• Checking the running condition of the onboard network area a Loads the (G1/4)  starter battery
• Extracts the function demands also during the operational phase
• Notes emergency operation in the failure coding
• Turns off during voltage surge
• Turns off during short out

The testing of the operating condition from the onboard computer is the premise for the engagement of the battery separation relay (K57)  and is summarized in the following table.

Charging the starter battery (G1/4) 

The starter battery (G1/4)  is loaded only during normal operation of  the Onboard computer.

The charging process is carried out dependent upon the starter battery temperature and the starter battery charge. This is achieved over the charging curve found in the onboard computer control unit (N82/1). 

After reaching the charge limit a maintenance charge follows. The starter battery temperature is not measured directly but in connection with the outside temperature and the engine radiator fluid temperature. This is computed in the onboard computer control unit (N82/1). 

Furthermore, in the onboard computer control unit (N82/1)  different charging voltage temperature curve values are stored. The outside temperature is established as a CAN message by the driver's SAM control unit (N10/10)  over the CAN passenger compartment and over the engine temperature from the ME control unit (N3/10)  through the CAN engine compartment.