Why does the automatic start-stop system require a special battery?

Every starting process requires a significant amount of energy from a car battery. To reliably supply a high starting current, the battery must be in very good condition. The engine is turned off several times during the journey, especially in modern vehicles with automatic start-stop systems. During these phases, the battery continues to supply energy to all electrical consumers. A standard starter battery (SLI) is not intended for this charge output (i.e. continuous discharging and charging).

Only a battery equipped with start-stop technology can meet these requirements and withstand the strain.

Starting a car that does not have an automatic start-stop system is usually a one-time event. While driving, the generator powers electrical consumers such as the entertainment system and navigation device, ensuring that the starter battery is not discharged during the journey.

The Start-Stop Battery is loaded twice:

The situation is different for vehicles equipped with start-stop battery. The battery is subjected to a series of start and stop periods as it travels through town. Even if the car is stopped at a traffic light and the engine is turned off, electrical consumers such as lights, windshield wipers, radios, and displays require power.

Short trips, in particular, pose a challenge to the battery. The charge acceptance of the battery decreases with age and in winter, so adequate recharging during short journeys is not always guaranteed. This can cause the battery to gradually discharge, to the point where it no longer has enough energy to start the engine. Because of the special technology, the internal resistance of AGM batteries remains significantly lower than that of conventional batteries over their entire life, ensuring sufficient charge acceptance over a long period, and AGM batteries can handle short journeys with many start-stop phases better.

Three benefits of AGM batteries:

  1. Outstanding cold-start characteristics:

Cold start current is high in AGM batteries. They start the starter motor quickly and reduce its running time. Because of the cycle stability of AGM batteries, the engine can be turned off and restarted several times at short intervals without risk of restarting difficulties.

  1. Charge state that is balanced:

The AGM battery in modern vehicles is not only charged by the generator, but it is also fed by the braking energy recovery system. Normal starter batteries must be kept fully charged at all times and thus cannot absorb the energy generated by recuperation. AGM batteries can be operated in the partial charge range, providing enough “extra” capacity to store the energy generated during braking.

  1. A large reserve capacity:

The large reserve capacity ensures that all types of electrical components are supplied with power. AGM technology’s cycle stability ensures power supply to components while also providing a high starting power. Even if the battery is not fully charged, for example, because electronic assistants and consumers ensure comfort during a stop, or the generator has been temporarily decoupled to reduce the load on the engine.

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