Abstract: A battery charging circuit, which can charge storage batteries upto the required voltage level, and prevent them from being overcharged by use of a thyristor, a temperature sensor and a current regulation means. The circuit uses a regulated switched B.sup.+ supply which is controlled by a transistor which is switched on and off by control of the thyristor. The circuit of the present invention consequently can protect not only the storage batteries themselves, but also the electronic circuits and instruments, which use the storage batteries as their power sources, from being damaged due to overcharging.