i didnt register but some info i read suggests i should...the IBS is part of the negative battery terminal by the way.
IBS Measuring /Evaluation Function
The measuring/evaluation function of the IBS electronics, continuously measures the fol- lowing values under all vehicle operating conditions:
Voltage (6 V to 16.5 V)
Starting Current (0 A to 1000 A)
Current (200 A to +200 A)
Temperature (-40°C to 105°C)
Closed Circuit Current (0 A to 10 A)
When the vehicle is stationary, the IBS is programmed to wake up every 14 sec. and makes the required measurements within approx. 50 ms in order to save power.
The measured values from the IBS are provided to the DME by way of the Binary Serial Data Interface (BSD) to calculate the State of Charge and State of Health for the battery.
State of Charge (SoC) is a calculated condition showing the current charge of the battery. SoC is used during key OFF periods to insure the battery maintains a suf- ficient charge to start the engine at least one more time.
State of Health (SoH) tracks the history of the battery in the vehicle. Charge/dis- charge cycles and times are monitored. SoH helps the DME determine the proper charging rates and anticipated battery life. Internal resistance of the battery is calcu- lated by the IBS from the current and voltage dip during engine start. The values are forwarded to the DME to calculate the SoH of the battery.
Software contained in the microprocessor of the IBS utilizes the measured values to cal- culate the State of Charge (SoC) of the battery during vehicle sleep mode and compares this information with that received from the DME/ECM pertaining to the battery SoC/SoH, during the period of time between engine OFF and deactivation of the DME main relay.
The current SoC/battery data is stored in the IBS every 2 hours over a 6 hour time frame, providing 3 - 2 hour snapshots of battery SoC information. The stored information/snap- shot data is overwritten every 6 hours. Whenever KL15 is activated the IBS updates the DME with the current closed circuit histogram/battery status information, byway of the BSD. Upon obtaining updated information the DME evaluates the new data and if a closed-circuit current draw is identified a fault will be stored in the fault memory of the DME.
10 E90 Voltage Supply & Bus Systems
Servicing the IBS
The IBS is very sensitive to mechanical stress and strain. It is serviced as a complete unit with the ground cable. The ground cable also serves as a heat dissipater for the IBS.
Particular attention should be paid to the following points in service: Do not make any additional connections at the negative terminal of the battery Donotmodifythegroundcable Do not make any connections between the IBS and the sensor screw Do not use force when disconnecting the ground terminal from the battery Donotpullatthegroundcable Do not use the IBS as a pivot point to lever off the ground terminal Do not use the connections of the IBS as a lever Use only a torque wrench as described in the repair manual Do not release or tighten the sensor screw