With Start-Stop technology, the engine turns off automatically when the car comes to a stop at a red light or in stationary traffic. The engine is started again when the driver engages the clutch or accelerator. This energy-saving technology results in considerably lower fuel consumption, saving as much as 10%. It also reduces CO2 emissions in equal measure and is extremely easy to use. Originally Start-Stop was fitted to vehicles with manual gear box. This is now being integrated into vehicles with automatic gear boxes.
The battery is the heart of every Start-Stop system, as the technology's primary responsibilities are powering electrical devices when the car comes to a stop and reliably restarting the engine – and that's no easy feat.
High cyclic stability and excellent charge acceptance are essential. A conventional lead-acid battery wouldn't be able to cope with the demands of the technology for long. At Johnson Controls we've therefore developed two types of battery: the VARTA Start-Stop Plus battery with AGM (Absorbent Glass Mat) technology and the VARTA Start-Stop battery with EFB (Enhanced Flooded Battery) technology. The latter is primarily fitted to vehicles with a more basic Start-Stop system.
The VARTA AGM battery features even higher cyclic stability and recharges more quickly than conventional lead-acid batteries. These characteristics are essential, especially when it comes to advanced systems which, in addition to the Start-Stop function, employ regenerative braking and other fuel-saving technologies. When the driver applies the brakes, some of the car's kinetic energy is converted into electrical energy and fed into the battery. So the battery needs to be able to recharge quickly and cope with the challenges posed by Start-Stop vehicles.