So called start/stop systems are becoming increasingly common in vehicles having internal combustion engines. These systems have a proven ability to provide fuel savings, especially during city driving. This is due to a shutoff of the internal combustion engine when not required to propel the vehicle and a restart thereof once required again.
However, a limitation of some start/stop systems is that the battery life for traditional lead acid batteries may be significantly reduced. Furthermore, traditional lead acid batteries may need to be sized up significantly in order to handle the increased energy throughput from start/stop, in order to be able to fulfill the required battery life.
To mitigate this limitation, some known start/stop solutions incorporate one large main battery, such as a conventional acid-lead battery, and one smaller size support battery. The support battery in such a known arrangement is arranged to supply the electrical system of the vehicle during warm-starts of the engine. A warm-start is the restarting of the engine that occurs after a relatively brief shut-down period, as during normal start/stop operation of the vehicle while driving.
However, such a known arrangement may suffer from some limitations in the case of an increased number of start/stop events, higher timing demands and also increased current consumption by various vehicle systems.