Start-stop system

Topics:

Introduction
Operation

Introduction:
With the start-stop system, the engine is switched off while the vehicle is stationary and started again at the moment the driver wants to drive off again. This can be while waiting at a traffic light or when waiting for an open bridge. A vehicle with a start-stop system falls under the “micro-hybrid” category.

Legislation prescribes that new passenger cars may not emit more than an average of 130 grams of CO2 per kilometer during the legally established driving cycle. This driving cycle consists of driving in different conditions and standing still. While stationary, fuel is consumed and CO2 is emitted, which is detrimental to the test. Passenger cars that have come onto the market since 2012 are therefore equipped with the start-stop system.

Vehicles that are equipped with a start-stop system often have a button on the dashboard with which the system can be temporarily deactivated. In that case, the engine will no longer be switched off. During the next drive, the system is automatically activated again. Permanently disabling the start-stop system is sometimes possible but not permitted: the vehicle would then no longer comply with the type approval.

Operation:
The start-stop system is activated when the vehicle is stationary. This is detected by the wheel speed sensors (ABS sensors). In vehicles with an automatic transmission, the engine can shut off when the brake pedal remains depressed. When the brake pedal is released, the engine starts and you can drive off immediately. In vehicles with a manual transmission, the gearbox often needs to be in neutral and the clutch not pressed. As soon as the clutch pedal is pressed, the engine starts.

The start-stop system will only operate if the following conditions are met:

Outside temperature above 3 degrees Celsius (may differ per brand).
Engine at operating temperature.
Battery sufficiently charged and at temperature. For this, the signal from the intelligent battery sensor is used.
Driver’s seat belt fastened in the buckle.
Driver’s door closed.
Bonnet closed.
Vehicle not on a slope.
Windscreen defrosting not active.
Particulate filter is not being regenerated.
Front wheels must not be turned too far.
Towbar not connected to a trailer.

If these conditions are not met, a message often appears in the dashboard stating: “Start-stop system deactivated”, or a symbol as in the image. This message also appears when the system is manually switched off with a button on the dashboard.