VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

FUB-FUB-FB-610021-K19 FUB-FUB-FB-610021-K19 - 48V vehicle electrical system - V.2, VIN: B228841

ISTA system 4.24.13.21290 Data version R4.24.13 Programming -

version data

VIN B228841 Vehicle 7'/G12/SEDAN/730Li/B48,-/AUTO/ECE/LL/2018/02

Int.lev.works - Int.lev.(cur.) - Int.lev.(tar.) -

Mileage -

48V vehicle electrical system

Caution!
To turn off or turn on the 48 V electrical system, the procedure in the repair instructions must be observed!
To replace the 48-V battery, the procedure in the repair instructions must be observed!

Note!
In order to prevent an electric arc from occurring when working on the vehicle or the 48 V electrical system when the electrical
system is switched off under load, it is switched off automatically as soon as the hood is opened. For this purpose, a switching
contactor, which is designed as a bi-stable relay, is built into the lithium-ion battery. Once the Body Domain Controller (BDC)
detects the signal from the hood contact switch, a Check Control message is generated and displayed in the instrument cluster.
Under certain conditions, the 48-V electrical system may be switched on again despite the bonnet being open. They include
battery charger connected or a system request.
If switching contactor is opened, there is no backup of the 12 V electrical system by the 48 V electrical system.

From November 2019, there will be an extension of the vehicle electrical system capacity in the form of Mild Hybrid Technology with the 1st
generation of the 48 V electrical system. For this purpose, new components with 48 volts are used. The new components also result in new
functionalities that serve to increase comfort, efficiency and dynamics.
The introduction of the Mild-Hybrid technology results in new functions with the following advantages for the customer:
l Reduction in carbon dioxide emissions
Braking energy is not lost, but is recovered electrically (recuperated). The combustion engine is supported while driving and is operated
in efficient operating conditions. This results into a reduction in consumption in customer operation by approx. 0.3 l/100 km.
l Improvement of automatic engine start-stop function (MSA)
The powerful 48 volt starter motor generator results in a noticeable improvement in the start duration of approx. 20 %. In addition, an
improvement in comfort in terms of acoustics and oscillations during the starting procedure is achieved. The starting procedures are
barely noticed. The first engine start of the day takes place by the pinion starter motor. If the engine temperature is greater than 60 °C,
the combustion engine is started by the starter motor generator.
l Coasting with combustion engine switched off
During the so-called engine off coasting, the combustion engine normally no longer runs at idling with the mild hybrid technology, but is
switched off. The drivetrain is decoupled in order to use the kinetic energy of the vehicle for movement. This can further reduce fuel
consumption by turning off the combustion engine. The engine is restarted virtually without delay by the powerful 48 volt integrated
starter/alternator.
l Improvement in dynamics by eBOOST
In partial load operation, the starter motor generator supports the combustion engine as an electrical machine. Due to its distortion-free
power output, the starter motor generator improves the acceleration behaviour, i.e. the spontaneity of the drivetrain. At full throttle, the
starter motor generator can temporarily increase the overall power of the drivetrain by 8 kW in certain operating ranges.

With the introduction of the 48 V electrical system, new terminal designations result for differentiation from the 12 V electrical system:
- Terminal 40 = 48 volt positive battery terminal = line colour purple

- Terminal 41 = 48 volt negative battery terminal

The 48 volt components are specially marked (ISO standard 6469-3) similar to the high-voltage components.

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Brief component description

The following components are described for the 48 V electrical system:
- Overview of 48 volt components

- 48 volt starter motor generator (control unit SGR48)

- 48 volt battery (control unit BATT48)

- Power Control Unit 48 volt (control unit PCU48)

- 48 volt power distribution box

Overview of 48 volt components

Index Explanation Index Explanation

1 Ignition capacitor 2 48 volt battery (control unit BATT48)

3 Power Control Unit 48 volt (control unit 4 48 volt starter motor generator (control
PCU48) unit SGR48)

5 48 volt power distribution box

Starter motor generator

The 48 volt starter motor generator is a control unit. The starter motor generator is an electrical machine. The starter motor generator can
work in 2 operating conditions:
- When operated as an alternator, the starter motor generator converts mechanical power from the belt drive into electrical power and
feeds this into the electrical system.

- During operation as a motor, the starter motor generator converts electrical power from the vehicle electrical system into mechanical
power and transmits this to the belt drive.
The starter generator is integrated in the belt drive. The gear ratio starter motor generator to crankshaft is 2.7 to 1.

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 Crankshaft belt pulley 2 Coolant pump

3 Pendular belt tightener 4 Starter motor generator

5 Air conditioning compressor 6 Drive belt

A pendular belt tensioner is located in the belt drive. The pendular belt tensioner adapts to the V belt depending on the load. This ensures
that the drive belt is always tensioned regardless of the direction of rotation.

The starter motor generator is a 5-phase electrical machine. The coolant-cooled power electronics consist of MOSFETs and a
microprocessor.
The control unit 48 volt starter motor generator (SGR48) is connected to the K-CAN8.

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 48 volts starter motor generator 2 six‐pin plug connection

(SGR48)

3 48 volts positive battery terminal 4 48 volts negative battery terminal

(terminal 40) (terminal 41)

5 Coolant connection 6 Coolant connection

Starter motor generator technical data:

Maximum power as alternator 12.5 kilowatt

Continuous power as alternator 2.3 kilowatt

Power as engine 8 kilowatt

Weight 9 kilograms

Due to its high power, the starter motor generator requires a cooling system.

48 volt battery (control unit BATT48)

The 48 volt battery is a lithium-ion battery.
The lithium ion battery is installed at the right rear of the engine compartment.
The cell modules consist of nickel, manganese and cobalt on the anode side. A mixture of lithium titanium oxide (LTO) is used on the cathode
side.
The working range of 48 volt battery (BATT48) is between -25 °C and 60 °C. The power is reduced at temperatures above 60 °C to 72 °C.
The voltage range is from 38 volts to 53 volts.
The control unit 48 volt battery (BATT48) is connected to the K-CAN8.

Index Explanation Index Explanation

1 48 volt battery (BATT48) 2 eight‐pin plug connection

3 Vent hole 4 48 volts negative battery

terminal (terminal 41)

5 Coolant connections 6 48 volts positive battery

terminal (terminal 40)

Setup and 48 volt battery technical data:

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 48 volt battery (BATT48) 2 Lid with connections

3 Battery electronics module 4 Cell modules

5 Heat exchanger 6 Battery housing

7 Shift protection

Nominal voltage 44 Volts

Number of battery cells 20

Capacity at 35 °C 11 Ampere hours

Power when charging at 35 °C 16 kilowatt

Power when discharging at 35 °C 13 kilowatt

Weight 10 kilograms

Due to its high power, the lithium ion battery requires a cooling system.

Power Control Unit 48 volt (control unit PCU48)

The 48 volt Power Control Unit is also a DC/DC converter. The DC/DC converter is the interface between the 12 V electrical system and the
48 V electrical system. The 48 volt Power Control Unit supplies the 12 V electrical system with energy from the 48 V electrical system.
Voltage range at the input is between 24 volts and 58 volts. Voltage range at the output is between 6 volts and 16 volts.
The 48 volt Power Control Unit (PCU48) is connected to the K-CAN8.
The flexible energy management and power management, which is in the engine control unit, provides the DC/DC converter with the required
output voltage and output current. In the event of a fault, the DC/DC converter itself regulates its control variables.

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 Power Control Unit 48 volts 2 Coolant connection

(PCU48)

3 1‐pin plug connection 4 1‐pin plug connection

5 1‐pin plug connection 6 eight‐pin plug connection

7 Coolant connection

DC/DC converter technical data:

Power 3 kilowatt

Maximum current 250 Ampere

efficiency rating 96 percent

Temperature range -40 °C to 70 °C

Due to its high power, the lithium ion battery requires a cooling system.

48 volt power distribution box

The 48 volts power distribution is installed e.g. in the left front in the engine compartment.
With the introduction of the 48 V electrical system, new terminal designations result for differentiation from the 12 V electrical system:
- Terminal 40 = 48 volt positive battery terminal = line colour purple

- Terminal 41 = 48 volt negative battery terminal

The 48 volts power distribution distributes the terminal 40 to the following components:
- Starter motor generator 48 volts (SGR48)

- Power Control Unit 48 volts (PCU48)

The 48 volts battery (BATT48) supplies the terminal 40 to the 48 volts power distribution:

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 Power distribution, 48 volts 2 Line to the starter motor

generator 48 volts (SGR48)

3 Line to the Power Control Unit 4 Positive battery terminal

48 volts (PCU48) 48 volts (terminal 40) from 48
volt battery (BATT48)

System functions
The following system functions are described for the 48 V electrical system:
- Functional networking of 48 V electrical system

- Cooling system

- Deactivation executed by crash signal

Functional networking of 48 V electrical system

The following illustration shows the functional networking.

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 Electric coolant pump 2 Pinion starter

3 Power distribution box, engine 4 48 volt battery (BATT48)

compartment

5 Power Control Unit 48 volts (PCU48) 6 Front right power distribution box

7 Body Domain Controller (BDC) 8 12 V battery

9 Power distribution box, right rear 10 Fuse box 3

11 Fuse box 12 Crash Safety Module (ACSM)

13 Front left power distribution box 14 Brake pedal travel sensor (only with
conventional DSC)

15 Brake vacuum sensor (only with 16 Digital Engine Electronics or Digital

conventional DSC) Diesel Electronics (DME or DDE)

17 Integrated supply module 18 48 volt power distribution box

19 48 volts starter motor generator 20 Dynamic Stability Control (DSC) and

(SGR48) virtual integration platform (VIP)

Cooling system
Due to their high power, the following components of the 48 V electrical system are integrated into the cooling system:
- 48 volt starter motor generator (control unit SGR48)

- 48 volt battery (control unit BATT48)

- Power Control Unit 48 volt (control unit PCU48)

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Index Explanation Index Explanation

1 Coolant radiator for low-temperature 2 Electric fan

coolant circuit

3 Expansion tank 4 Coolant pump, low-temperature coolant

circuit 48 V

5 Primary coolant thermostat 6 Coolant pump

7 Shift element 8 Coolant temperature sensor

9 Engine 10 48 volt battery (BATT48)

11 Power Control Unit 48 volts (PCU48) 12 SCR metering module

13 Heat exchanger for heating system 14 Oil‐to-water heat exchanger

(transmission)

15 High pressure exhaust-gas recirculation 16 Engine oil-to-water heat exchanger

cooler (engine)

17 Starter motor generator 48 volts 18 Secondary coolant thermostat

(SGR48)

19 Expansion tank 20 Radiator

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VIN: WBA7E01000B228841 FUB-FUB-FB-610021-K19 V - 2

Deactivation executed by crash signal

For safety reasons, the control units 48 volt battery (BATT48) and 48 volt Power Control Unit (PCU48) have a terminal 30C (terminal 30 crash
signal). Terminal 30C is disconnected from the 12 V battery in case of a crash from the crash safety module (ACSM).
The voltage drop at terminal 30C leads to an immediate system shutdown. The 48 volt Power Control Unit (PCU48) is shut down. The
switching contactor of the 48 volt battery is disconnected under load.
If terminal 30C is accidentally disconnected, this disconnection is automatically regenerated after the connection is re-established. The fault
memories in the components document this disconnection.

Notes for Service department

General notes
When servicing in the workshop, the switch-off is initiated as soon as the hood of the vehicle is opened. This shuts down the 48 V electrical
system and remains as it is until the following is detected:
- Close the bonnet

- PWF status, driving

- External charge

Index Explanation Index Explanation

1 Instrument panel (KOMBI) 2 48 V electrical system

switched off

Note!
The vehicle battery continues to be externally charged via the jump start terminal in the engine compartment.

Diagnosis instructions
After renewing the lithium ion battery, it has to be registered. A service function is available in the diagnosis accordingly:
Path: Body > voltage supply > 48 V electrical system > Register 48-V battery

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any
time.

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