An electromechanical transfer circuit to measure individual battery voltages in series packs

A novel approach has been developed to measure the voltages of individual batteries used in electric vehicle (EV) battery packs using a unique selective battery measurement system. This system consists of a voltage measurement circuit that measures battery voltages using a set of electromechanical relays connected in a matrix formation. A 16-bit microcontroller was used for controlling the operation of the relay matrix circuit. The system was designed for a pack of 12 series connected 12 Vdc lead–acid batteries. The proposed approach was found to be compact and is a universal one that can be used for any type of battery. Moreover, the method was very effective and produced good accuracy. In fact, test results over a wide temperature range of −20 to +40 °C indicated that the method is very precise with voltage fluctuations less than ±30 mV.