Fig 3: How the Smart Battery subsystem works
Batteries occasionally need to be charged. The battery charging circuit is intelligent; one of its tasks is to deliver the appropriate charging currents for the selected battery type. Depending on temperature, battery condition and load volume, the charging circuit decides in collaboration with the SBM how high the currents have to be and how long they flow. The SBM relies on information it receives from the battery, such as the charge status and internal temperature. Similarly, the charging currents depend on the energy available via the power supply and the necessary division of power between application and battery. The decision whether multiple batteries must be loaded sequentially or in parallel, depends on the application. The requirements for the charging circuit are as contradictory as those for the battery pack – powerful, but at the same time small and light.
5. The overall concept
A common requirement is for the battery to last as long as possible. Ideally, an entire working day, but at least for the duration of an application. The operating time of a mobile device depends on the capacity of the battery, the consumption of the device and the overall power management concept. The optimal solution is different for each application. Let us look at two examples.
Medical emergency versus industrial setting
In most cases, an emergency doctor will place the mobile device after use straight back into the charging unit in the ambulance or rescue helicopter. It can recharge quickly and is then ready for the next patient. The load current will likely be high and the charging cycle short. The focus is on standby; the battery life is secondary. The battery