Overview
This document contains the following information:
General
Function requirement
Charging via alternator/recuperation
Emergency cutoff
General
When charging the battery using the alternator, the rotational energy of the drivetrain is used to generate energy. The alternator can be driven by the combustion engine or by the vehicle's kinetic energy through the drivetrain, and it generates electrical energy while doing so (recuperation).
The voltage for charging the battery is generated by one of the following component parts depending on the vehicle version involved:
12 V alternator (vehicles with 12 V alternator)
Starter-alternator (vehicles with 48 V technology)
Electric machine (hybrid vehicles, electric vehicles)
Vehicles with 48 V technology
Dependent on the number of 48 V consumers, a conventional 12 V alternator may be installed instead of the starter-alternator.
Function requirement
Combustion engine running or vehicle rolling
Charging via alternator/recuperation
The power output of the respective energy converter is controlled by alternator management during charging. The alternator management sets the nominal charging voltage here.
In order to charge the battery, the charging voltage must first be determined. To do this, the condition of the battery, the generative operating rate of the energy converter and additional input factors (e.g. air conditioning system ON) are taken into account. In addition, the input factors are checked for plausibility in order to eliminate overcharging or insufficiently charging the battery. The specifications are continuously compared with the actual power output. The comparison of these two values and the corresponding corrections are referred to as power management. Power management ensures that the battery is not overloaded. If the on-board electrical system voltage is too low, power management is gradually reduced. The energy converter can then make its full output available.
If an error is found when detecting the condition of the battery, energy management switches to a fixed voltage.
Emergency cutoff
The emergency shutoff prevents the battery from being overcharged through a long overrun mode fuel shutoff (e.g. during long downhill descents). Die recuperation and therefore the charging of the battery at high voltage with a low power consumption is deactivated. The charging voltage is lowered in order to return to the optimum charge level when the battery is fully-charged.
Function schematics | |||
Function schematic for charging high-voltage battery through alternator/recuperation | Model 167 with engine 654.8 with code ME05 (HYBRID DRIVE 80KW VARIANT (INCLUDING PLUGIN))Model 177, 247 with engine 282 with code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN)) | ||
Model 293 with engine 780 | |||
Function schematic for charging on-board electrical system battery for 12 V on-board electrical system through alternator/recuperation | Model 118Model 167 with engine 656 with code B01 (48V technology)Model 167 except code B01 (48V technology) except code ME05 (HYBRID DRIVE 80KW VARIANT (INCLUDING PLUGIN))Model 177, 247 except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN)) | ||
Function schematic for charging on-board electrical system battery for 48 V on-board electrical system through alternator/recuperation | Model 167 with code B01 (48V technology) | ||
Control units | |||
Combustion engine control unit, basic function | Model all (CAR) | ||
Power electronics control unit, basic function | Model all (CAR) | ||
Electric drive powertrain control unit, basic function | Model 293 | ||
Powertrain control unit, basic function | Model all (CAR) | ||
Basic function of signal acquisition and actuation module | Model 118, 177, 247 | ||
Basic function of signal acquisition and actuation module at front | Model 167 | ||
Components | |||
Electric machine, basic function | Model all (CAR) | ||
Integrated starter alternator, basic function | Model all with engine 256 | ||
Alternator, basic function | Model all (CAR) |