Charging techniques for a universal lead-acid battery charger

Several methods were investigated during the course of the development of a smart charger for lead acid batteries. They include constant voltage and constant current techniques, in addition to a method based on the estimated maximum number of cells and a couple of others based on the estimated minimum number of cells in the battery. The former two methods are well known. The estimated maximum and minimum methods are presented here. The minimum and maximum number of cells are calculated from the measured open circuit voltage. The most suitable and safest one involves determining the minimum number of cells in the battery and using this value to determine the charge voltage. This method takes full advantage of the microprocessor capabilities of current chargers for diagnostic purposes and can be used to charge any size lead acid battery. The details of these methods and their merits and limitations are discussed