The intelligence needed for the BMS can be divided between the various parts. This partitioning of intelligence is an important aspect in designing a BMS. The main determining parameter in this respect is cost. Dedicated battery management ICs can implement intelligence. Useful background information with many examples can be found in [1]-[15]. Measured variable and parameter values and control commands are communicated between the parts of the BMS via a communication channel. This channel can be anything from a single wire that controls a Pulse-Width Modulation (PWM) switch to a bus that is controlled by a dedicated protocol [16]-[18]. The structure of a general BMS is shown in Figure 2.1. The partitioning of intelligence is symbolized by placing a ‘Monitor and Control’ block in every system part. The BMS shown in Figure 2.1 also controls a Battery Status Display. An example is a single Light-Emitting Diode (LED) that indicates the ‘battery low’ status. It can also be a string of LEDs indicating the battery’s State-of-Charge (SoC) or a Liquid-Crystal Display (LCD) that indicates the battery status, including the SoC and the battery condition.