Code 51a6?

Hello,

Yes, the IBS fails on the inside.

The intelligent battery sensor (IBS) is an intelligent, mechatronic component that monitors the battery condition.
The power supply to the IBS is provided through a separate wire.
For the purpose of data transmission, the IBS is connected to the digital engine electronics (DME) or digital diesel
electronics (DDE) via the bit serial data interface (BSD).
The intelligent battery sensor (IBS) consists of mechanical components, the electronics module and software.
- Mechanical components
The battery terminal with earth cable is the connection to the negative terminal of the battery and serves
 to create an electrical contact to the body
 as the support for the sensor element for current measurements
 as the support for the electronic module
 to provide an adequate thermal contact between the temperature sensor and the negative terminal of the battery
 as protection for the sensitive electronic module
 as an earth connection for the IBS

The mechanical parts are listed in image 1.

Electronic module:
The electronic module has the task of recording the voltage, the current flow and the temperature of the battery. The
following components are housed in the electronic module:
 a shunt (resistance for current measurement)
 a temperature sensor
 an electronic evaluation unit on a board
The board, which is about the size of a fingernail, contains an electronic circuit for evaluating the data measured.
The intelligent battery sensor (IBS) is able to withstand thermal loads of up to 105 °C and the chemical effect of the battery
acid. The IBS thus satisfies the necessary conditions for installation in the engine or luggage compartment.
The components of the shunt are illustrated below in image 2

How it works:
The functions of the intelligent battery sensor (IBS) are:
- To continuously measure battery data in all vehicle operating modes
- To compute battery indicators as basis for battery charge state (SoC: "State of Charge") and battery condition (SoH: State of Health")
- To balance the charge/discharge current of the battery
- To monitor the battery's charge state (SoC) and to activate the electric energy management and power management
for countermeasures if the battery charge state becomes critical (battery's limit of starting capability).
- To identify initial data for calibrating the battery charge state (SoC: "State of Charge")
- To calculate the starting current curve to determine the battery condition (SoH: "State of Health")
- To monitor off-load current
- To transmit data to the higher-order control unit (DME or DDE)
- Self-diagnosis
- To perform fully automatic updates of algorithm parameters and parameters for self-diagnosis via DME / DDE
- To be able to independently "wake up" from sleep mode

Cheers, Boris