BATTERY MONITORING SYSTEM (BMS)
The BMS (Battery Monitoring System) control module is located on the battery negative terminal, and connected to the
BCM/GWM assembly via a LIN bus connection. The BMS module contains software maps that provide a mathematical model of
battery conditions, and constantly receives information from the BCM/GWM assembly regarding the vehicle state and electrical
loading.
The BMS control module monitors various battery parameters, which are directly measured and predictive values:
Battery current and voltage are the result of direct measurement;
while State of Charge (SoC), State of Function (SoF) and electrolyte temperature are predicted values.
These signals are used by both the charging system and the stop/start system to ensure the vehicle functions are optimized.
The measurement is autonomous and happens in all states to enable an accurate condition of the battery to be assessed at all
times. Software based values are calculated and used as a backup in the event of a system fault condition.
The BMS control module also has a hardwired connection to the battery positive terminal. This connection is used to avoid any
potential voltage drop in the circuit which results incorrect information received by the BMS control module. If this connection
becomes open, the BCM/GWM assembly detects a communication loss with the BMS control module. Then the BCM/GWM
assembly default to a fail-safe fixed charging voltage of 14 Volts, stores a related DTC, and sends a message to the
Instrument Cluster (IC) via the MS Medium Speed (MS) Controller Area Network (CAN) comfort systems bus to illuminate the
charge warning indicator.
OPERATION
The charging system consists of a generator and regulator assembly and the BCM/GWM assembly. The generator and
regulator assembly generates electrical power for the vehicle electrical system and maintains the battery in a charged state.
The rate of charge for the battery is controlled by the BCM/GWM assembly.
The charging voltage range is 12.3V to 14.8V (at the battery).
A smart regenerative charging system increases the alternator output when the vehicle brakes or decelerates. This converts
the kinetic energy of the vehicle into electric energy without having to use additional fuel.
The smart regenerative feature is allowed to operate within certain environmental constraints to ensure the feature delivers
the greatest benefit possible whilst maintaining system integrity.
The ‘free’ electric energy is captured by charging the battery above the target level. This energy can be used by the electrical
systems at a later stage. This could be when the engine is switched off during a stop-phase, but can also be when the
generator is operating in a less efficient mode.
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