Efficient energy accumulator nitrogen charging device and method

The invention belongs to the field of energy storage equipment, and particularly relates to an efficient energy accumulator nitrogen charging device which comprises a nitrogen assembly, and the nitrogen assembly comprises a nitrogen supply device and a gas inlet one-way valve allowing nitrogen in the nitrogen supply device to flow into other parts of the device. The device is provided with a multi-cavity piston, the multi-cavity piston comprises a main cavity, a piston capable of doing reciprocating motion is arranged in the main cavity, the main cavity is divided into a plurality of branch cavities by the piston, and each branch cavity comprises a plurality of air inlet cavities communicated with a nitrogen assembly and an energy accumulator. An inflation one-way valve enabling gas in the gas inlet cavity to flow into the energy accumulator is arranged between the gas inlet cavity and the energy accumulator. The device further comprises a power source used for driving the piston to reciprocate in the main ca