When the power supply is restored all parameters are out of range because the system is not
able to determine the battery status yet.
At the first starting it performs the SOF calibration, considering immediately the minimum voltage
already reached at the first starting. The other parameters cannot be taken into account yet.
After a period of inactivity longer than 4 hours and at least a starting cycle, the SOC parameter
is also considered, which determines the battery charge status after a certain period of time has
elapsed. The state of health - SOH - is not considered yet because it is still necessary to alternate
start-up cycles and inactivity periods. The real efficiency status of a battery can be determined if also
the elapsed operation time is considered.
After 5 inactivity periods of at least 8 hours, combined with a series of starting attempts, the
cycle ends and the SOH parameter is acquired and stored.
If the IBS does not recognize the values of the above mentioned parameters, the system will
appropriately limit the engine stopping and starting cycles to ensure that the battery recharges
correctly.
Conclusion:
The IBS exits the calibration stage when the SOC and SOF evaluations are within the
tolerances, as shown in the previous table. This occurs after a rest stage (engine off) of at
least 4 hours followed by a starting.
Use of information supplied by the IBS
Engine on conditions
In engine on conditions, the BCM uses the information received from the IBS to activate or
deactivate a possible automatic stop on the basis of the battery starting capacity estimated by the
IBS.
As already mentioned, the starting capacity of the battery is usually evaluated through the battery
status, expressed as SOC, SOF, SOH and temperature; when, on the other hand, the IBS is being
recalibrated, some status variables are not reliable and therefore only the SOF and the battery
temperature are taken into account.
The request to enable/disable an automatic stop by the BCM is translated into a signal produced
by the BCM and sent, through the C-CAN, to the ECM.
The following flow-chart describes the strategy used by the BCM to manage the information from the
IBS and the automatic stop enabling/disabling.
When the engine automatic stop is enabled by the BCM, the ECM is enabled to automatically
switch off the engine if the driving conditions (actions on the brake, clutch and accelerator pedals) are
satisfied in the same way as the other conditions controlled by the ECM.
When the engine automatic stop is disabled by the BCM, the ECM is not enabled to automatically
switch off the engine, even if the driving conditions (actions on the brake, clutch and accelerator
pedals) are satisfied in the same way as the other conditions controlled by the ECM.
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