Energy Management For ECO Start/Stop Function, Basic Function - GF54.10-P-1009A
Model 118, 167, 177, 206, 223, 247
Model 213, 238, 257, 290 as of model year 2021
Overview
This document contains the following information:
- General
- Function requirements
- ECO stop
- ECO start
- Vehicles with conventional drive concept (only combustion engine)
- Vehicles with 48 V technology
- Hybrid vehicles without backup concept with integrated disconnection module
- Hybrid vehicles without backup concept and without integrated disconnection module
- Hybrid vehicles with backup concept
- Forced engine start
General
The ECO start/stop function switches off the combustion engine under certain conditions when the vehicle is stationary. Switching off the combustion engine reduces the fuel consumption and therefore the carbon dioxide emissions.
In vehicles with conventional drive concept, the combustion engine is restarted when the driver wishes to move off.
Hybrid vehicles can also move off under purely electrical power depending on the charge level of the high-voltage battery. If the charge level of the high-voltage battery is too low, the combustion engine is started.
It is still possible to stop and start the combustion engine in the conventional way.
Function requirements
- Combustion engine running and at operating temperature
- 12 V on-board electrical system battery charged sufficiently
- Vehicles with conventional drive concept:
- Outside temperature -10 to 40°C
- 12 V on-board electrical system battery temperature 0 to 60°C
- Hybrid vehicles:
- Outside temperature -40 to 60°C
- 12 V on-board electrical system battery temperature -40 to 60°C
ECO stop
The combustion engine control unit checks all engine-relevant parameters and then issues the stop enable signal. The ECO start/stop function checks other input factors, e.g. the on-board electrical system load.
The energy management provides information which describes the on-board electrical system status or the demands on the on-board electrical system:
- Condition of the 12 V on-board electrical system battery
- Condition of the 48 V battery (vehicles with 48 V technology)
- Condition of the ECO start/stop auxiliary battery (hybrid vehicles with backup concept)
- Load on on-board electrical system
After evaluating this information, the ECO start/stop function requests the combustion engine to be switched off. The combustion engine control unit stops the engine running and transmits the signal "Drivetrain operational" via the vehicle's network architecture. This prevents the energy management system from reducing or switching off consumers if the "Engine running" signal is not sent.
After one ECO stop has occurred, only one further ECO stop is permitted if a speed of 8 km/h is not exceeded. Then the speed of 8 km/h must be exceeded once. If the hood is opened during an ECO stop, the ECO start/stop function is switched off.
Vehicles with 48 V technology, hybrid vehicles
The combustion engine can also be switched off in connection with system optimizations. For example, to convert the kinetic energy of the vehicle into electrical energy (recuperation).
ECO start
The combustion engine is restarted when the driver wishes to continue his journey.
The following events lead to an ECO start:
- Vehicles with manual transmission:
- The clutch pedal is depressed.
- The vehicle moves off.
- Vehicles with automatic transmission:
- The brake pedal is released (when the HOLD function is not active and the selector lever position is "D" or "N").
- The accelerator pedal is operated.
- The transmission mode is changed.
- The selector lever position "R" is engaged.
- The selector lever leaves the "P" position.
The ECO start/stop function evaluates these events and requests the combustion engine control unit to start the combustion engine. When the engine speed reaches 400 to 700 rpm, the starting procedure is ended.
Vehicles with conventional drive concept (only combustion engine)
The combustion engine is started with the starter. Due to the high start-up current of the starter during the ECO start, the 12 V on-board electrical system voltage drops severely. Active electrical consumers could be switched off briefly. A voltage dip limiter or a front-end relay prevents any excessively severe voltage drop. The power consumption of the starter is reduced during the startup phase of the combustion engine by the activation of a series resistor. If the 12 V on-board electrical system voltage drops too sharply, the voltage dip limiter or the front-end relay switches the series resistor off again.
Vehicles with 48 V technology
The combustion engine is started with the starter-alternator. The power to start the combustion engine is provided by the 48 V on-board electrical system.
Depending on the number of 48 V consumers involved, a conventional alternator may be installed instead of the starter-alternator. In this case, the starting procedure is identical to that for vehicles with a conventional drive concept.
Hybrid vehicles without backup concept with integrated disconnection module
After an ECO stop, the combustion engine is usually started with the starter. The integrated disconnection module prevents an excessively strong voltage drop. It disconnects the 12 V on-board electrical system battery and the starter from the 12 V on-board electrical system. The 12 V on-board electrical system battery now solely provides the energy for the starting procedure of the combustion engine. The 12 V on-board electrical system is supported by the high-voltage on-board electrical system via the DC/DC converter. This prevents any voltage drop being noticed by vehicle occupants when the engine is being started (e.g.during radio or ventilation operation). The 12 V on-board electrical system battery and the starter are reconnected to the 12 V on-board electrical system after the starting procedure. If the 12 V on-board electrical system voltage drops too much during the starting procedure, the integrated disconnection module interrupts the starting procedure.
In the event that the load of the DC/DC converter is higher than 90%, the combustion engine is not started with the starter, but with the electric machine. The power to start the combustion engine is provided by the high-voltage on-board electrical system.
Hybrid vehicles without backup concept and without integrated disconnection module
After an ECO stop, the combustion engine is started with the electric machine. The power to start the combustion engine is provided by the high-voltage on-board electrical system. If the charge level of the high-voltage battery is too low, the combustion engine is started with the starter. A voltage dip limiter or a front-end relay prevents any excessively severe voltage drop. The power consumption of the starter is reduced during the startup phase of the combustion engine by the activation of a series resistor. If the 12 V on-board electrical system voltage drops too sharply, the voltage dip limiter or the front-end relay switches the series resistor off again.
Hybrid vehicles with backup concept
The combustion engine is started with the starter. The energy management system connects the ECO start/stop auxiliary battery to the 12 V on-board electrical system. The ECO start/stop auxiliary battery takes over the power supply of the active consumers. The 12 V on-board electrical system battery is isolated from the 12 V on-board electrical system and provides the energy for starting the combustion engine. This prevents any voltage drop being noticed by vehicle occupants when the engine is being started (e.g. during radio or ventilation operation). After the starting procedure, the 12 V on-board electrical system battery is reconnected to the 12 V on-board electrical system and the ECO start/stop auxiliary battery is disconnected from the 12 V on-board electrical system. The energy requirement of the 12 V on-board electrical system is then supplied again solely by the 12 V on-board electrical system battery.
Forced engine start
To ensure that the on-board electrical system is also stable during an ECO stop, the combustion engine can be force-started. A forced start is also performed if, e.g. due to the requirement of load-intensive consumers, the stability of the on-board electrical system can no longer be guaranteed.
The following events result in a forced engine start:
- The on-board electrical system voltage decreases.
- The coolant temperature increases above 115°C.
- The ECO stop lasts longer.
- The vehicle moves at more than 2 km/h forwards or it rolls backwards.
- The temperature in the vehicle interior moves out of the set range or the windshield is fogged on the inside.
- The vacuum in the brake booster decreases.
- The ECO start/stop function is deactivated.
- Vehicles with 48 V technology, hybrid vehicles
The combustion engine can also be force-started in connection with system optimizations. For example, when the state of charge of the 48 V battery or the high-voltage battery drops below a defined limit.
If the energy management system is no longer able to guarantee the stability of the 12 V on-board electrical system, or if one of the events described above occurs, the combustion engine will be started immediately. If the stability of the 12 V on-board electrical system still cannot be guaranteed afterwards, the combustion engine will not be switched off again. The ECO start/stop function is deactivated.
| Function schematics | |||
| Function schematic, ECO start/stop function energy management | Model 118, Model 167 except code B01 (48V technology) except code ME05 (Hybrid drive 85 kW-94 kW variant (incl. plug-in)) Model 177, 247 except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN)) | PE54.10-P-2500-97A | |
| Model 167 with code B01 (48V technology) | PE54.10-P-2500-97B | ||
| Model 167 with code ME05 (Hybrid drive 85 kW-94 kW variant (incl. plug-in)) Model 177, 247 with code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN)) Model 213 as of model year 2021 with code ME05 (Hybrid drive 85 kW-94 kW variant (incl. plug-in)) except code B01 (48V technology) Model 213 as of model year 2021 with code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN)) except code B01 (48V technology) | PE54.10-P-2500-97C | ||
| Model 213 as of model year 2021 except code B01 (48V technology) except code ME05 (Hybrid drive 85 kW-94 kW variant (incl. plug-in)) except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN)) Model 238, 257, 290 as of model year 2021 except code B01 (48V technology) | PE54.10-P-2500-97D | ||
| Model 213, 238, 257, 290 as of model year 2021 with code B01 (48V technology) | PE54.10-P-2500-97E | ||
| Model 223 except code B01 (48V technology) except code ME10 (Hybrid vehicle) | PE54.10-P-2500-97F | ||
| Model 206, 223 with code B01 (48V technology) except code ME10 (Hybrid vehicle) | PE54.10-P-2500-97G | ||
| Model 223 with code ME10 (Hybrid vehicle) | PE54.10-P-2500-97H | ||
| Additional basic functions | |||
| Automatic start, basic function | GF07.10-P-1052A | ||
| Automatic stop, basic function | GF07.10-P-1053A | ||
| Combustion engine forced start, basic function | GF07.10-P-1059A | ||
| Control units | |||
| Combustion engine control unit, basic function | GF07.08-P-9890A | ||
| Powertrain control unit, basic function | GF54.21-P-9894A | ||
| Basic function of signal acquisition and actuation module | Model 118, 177, 247 | GF54.21-P-9895A | |
| Basic function of signal acquisition and actuation module at front | Model 167, 206, 223 Model 213, 238, 257, 290 as of model year 2021 | GF54.21-P-9896A |