Abstract: A control device for a storage battery consists of a charge regulating loop including a circuit for supplying clock pulses having a variable frequency proportional to a battery charge and discharge current, a circuit for estimating an instantaneous capacity of the battery depending on a clock pulse up-down count, and a regulating circuit for recharging the battery from a mains or supply voltage as soon as the instantaneous capacity is equal to a first capacity substantially less than a maximum capacity of the battery. According to the invention, the frequency of the clock pulses depends also on at least one of the parameters relating to an energy efficiency of the battery and to a self-discharge current of the battery, so that these parameters are involved in estimating the instantaneous capacity. Also, the device gives warning, through an alarm, that the battery voltage is considerably more than a discharge threshold which, when reached, disconnects the battery from a load circuit.