The dashboard of a car with the clock on the left side, the speed indicator on the right side and a start stop sign in the middle

The Basic Principles of Start-Stop Technology

Start-stop systems automatically shut down and restart the engine to reduce the amount of time it's idling, therefore cutting down on fuel consumption and emissions. The majority of manufacturers choose to fit VARTA® batteries in their start-stop vehicles rolling off the production line.

The battery is at the heart of the car. It powers everything – from the ignition to continuously operating vehicle electric systems and onboard entertainment systems. The battery ensures constant power for all other functionalties during the start-stop process. Those batteries have to do much more than just starting the car. That’s why the BATTERY is the HEART of your vehicle.

Today most new cars have start-stop functionalty, which is why we have created two innovative VARTA® batteries with start-stop capability: VARTA® Silver dynamic with AGM technology for advanced start-stop vehicles with regenerative braking, and Blue dynamic with EFB technology for conventional start-stop vehicles.

Driving & Accelerating

An advanced energy management system decouples the alternator during acceleration and under normal driving conditions. This means more of the engine's power is available to the wheels. The alternator is only recoupled again when the battery's state of charge falls below a predefined threshold.

Battery requirements:

Battery is being discharged and charged and must supply all electronic devices on its own.


Regenerative braking partially allows the vehicle's kinetic energy to be converted into electrical energy, which is then fed back into the battery.

Battery requirements:

The battery needs to be recharged quickly and have sufficient capacity for the additional energy. The battery must be capable of functioning at a lower state of charge.

Stop & Engine Off

When the vehicle comes to a stop, the start-stop system switches off the engine.

Battery requirements:

Even when discharged, the battery must still supply the starter motor generator with sufficient starting power to start the engine again.

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