To begin, what exactly is Start-Stop Battery? Governments have put pressure on automakers to make vehicles that are more fuel efficient. This has been accomplished through a variety of methods. There are numerous, but this blog does not intend to list them all. The first is obvious: when you stop at a traffic light or wait in traffic, the engine turns off. When you press the accelerator, the engine starts and the car pulls away.
Because the alternator consumes about 10% of the engine’s power, when the battery is charged, the ECU (engine control unit) turns off the alternator, saving power and fuel. When braking, some of the power generated is used to charge the battery.
Because of the way the battery is discharged, it is necessary to recharge the battery quickly in order to keep up with the demands of the vehicle’s electrical system. As a result, a new generation of batteries for Stop-Start Battery has been developed.
Lead acid starter batteries are made up of a series of lead grids called plates. The active material is a lead compound that has been pasted onto these plates; because pure lead is very pliant, it is difficult to form a grid. As a result, the lead has been allowed to give the grid its rigidity. When County Battery Service first started in 1974, almost all starter batteries were made of lead antimony. There are obvious benefits, but the disadvantage with antimony is that the battery gassed at a low voltage and thus consumed a lot of water. This method of construction has largely been replaced over the years by a lead calcium alloy, which allows for a higher rate of charge before gassing, making these batteries almost maintenance free.
The AGM battery has been popular in the market since the 1970s, but it has mostly been used in emergency power and telecom systems. These batteries have now been developed using high purity lead with a calcium grid, allowing for a faster higher voltage and amperage charge rate while requiring little maintenance for use in start/stop vehicles.
AGM batteries require a different charging algorithm than standard flooded batteries. Traditional battery chargers increase the voltage of the battery as it charges, and as the voltage increases, the amperage going into the battery decreases. You may have noticed that as the battery charges, the amperage needle on the charger falls; if left on, the battery begins to heat up and the electrolyte begins to bubble. If this much gassing occurred in an AGM battery, the vents in the battery would open (to prevent explosion) and the gases would escape, rendering the battery unusable. A new generation of chargers has emerged alongside a new generation of batteries. Rather than a needle, these chargers are typically electronic, with lights indicating the state of charge. To prevent overcharging, these chargers use fixed charging algorithms that limit voltage and amperage.