A battery tester is an electronic device intended for testing the state of an electric battery, going from a simple device for testing the charge actually present in the cells and/or its voltage output, to a more comprehensive testing of the battery's condition, namely its capacity for accumulating charge and any possible flaws. The most simple battery tester is a DC, that indicates the battery's. DC can be used to estimate the charge rate of a battery, provided that its nominal voltage is known. There are many types of integrated battery testers, each one corresponding to a specific condition testing procedure, according to the type of battery being tested, such as the “421” test for. Their common principle is based on the empirical. • By Edward Abdo• By Jack Erjavec• edited by George S. Day, David J. Reibstein.