This invention discloses a type of charging system for electric cars which includes an AC electric grid power supply system and an electric car charging equipment. The AC electric grid power supply system couples energy outputs to the electric car charging equipment; its characteristics are: it also includes an battery power system and an electrical energy control module. The electrical energy input of the battery power system is controlled by and connected to the AC electric grid power supply system. The output is controlled by the electrical energy control module and coupled to the electric car charging equipment. With the addition of one or more battery packs to the battery charging system, instantaneous current increase can be provided through the use of the battery packs in order to alleviate the demand on the electric grid. The design capacity of the battery charging system is more ideal and it reduces the instantaneous capacity overload. Meanwhile when the external electric grid fails, it can rely on the battery packs to charge electric cars and thus resolving any urgent charging needs.