Batteries in start-stop systems – how to replace and what to pay special attention to?

The start-stop system installed in new cars is slowly becoming the standard. There are also more vehicles of this type in service stations, where periodic heart inspections of the whole system, which is the battery, are performed. When it comes to its control, there are no major problems. The latter, however, begin when you need to replace a used or damaged battery with a new one. - start stop.


The first difficulty may be the location of the battery itself. While in the case of vehicles without a start-stop system, it is almost always under the hood, while in cars equipped with this system the battery can be installed in a completely different place, including in the passenger cabin (e.g. under one of the seats) or in the trunk. Due to the location of the battery in the vehicle, its model and replacement procedure, the total time of replacing a worn or out of order one with a new one may be extended up to four times compared to standard batteries in cars without a start-stop system.


Before making the right choice of battery, you need to know what type of start-stop system we are dealing with. Due to the complexity we distinguish two: basic and advanced. In both of them, the operation of the start-stop system consists in switching off the engine when the vehicle stops and restarting it to continue driving (e.g. at intersections with traffic lights). An advanced type of start-stop system, on the other hand, is distinguished by additional functionality, consisting of the possibility of accumulating additional energy from braking (the so-called recuperation process) and limiting battery charging at the time of acceleration (through the alternator).


In the basic start-stop system it is recommended to use batteries manufactured in the EFB (Enhanced Flooded Battery) technology. They are characterized by a special polyester coating on the positive plate, which helps to keep the active mass of the battery in the plate. Thanks to this solution, EFB batteries have twice the cyclic durability compared to conventional batteries, supplying electric receivers in the car with the engine off and guaranteeing immediate restart of the engine.

Whereas in advanced types of start-stop system batteries in AGM (Absorbent Glass Mat) technology should be used. In AGM technology, fiberglass mats saturated with electrolyte are placed between the lead plates, which increases the efficiency of the battery. AGM batteries compared to EFB are more efficient because they can supply more electricity to consumers and operate at very low charge levels.

Attention! Professionals allow the possibility of installing the AGM battery in a vehicle that previously had an EFB battery. Inverse installation is not recommended.

And what about the case when using a conventional battery in a vehicle with a start-stop system? This is not profitable for purely financial reasons: it will wear out prematurely within three weeks to five months.


Installing a new battery adapted to a particular type of start-stop system is not enough. It is necessary to adapt it (encode) with the on-board computer. Why is this so important? It is about ensuring proper energy management in the vehicle and proper charging. The adaptation (coding) process usually involves entering the part catalog code and the battery code. If the adaptation step is omitted, it may happen that individual elements of the start-stop system will not function properly.

Attention! In some vehicles with a start-stop system, the adaptation of the new battery is automatic, while in others it is done manually, using a computer or device with appropriate software and connecting to the EOBD socket. TEAM

Audi maniac, owner of and big fan of Audi cars. Maps, firmware, car audio installer
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