PURPOSE: To prevent a difference from being made between the concentration of the upper portion of an electrolytic solution and that of the lower portion thereof, by housing an air compression pump and a bubble pump together in the jar of a leaden storage battery to place the bubble pump in the electrolytic solution, and driving the pumps by the electromotive force of the battery itself.

CONSTITUTION: A plunger-type air compression pump 10 is attached to the jar lid 2 of a leaden storage battery of relatively large height. A bubble pump 18 is provided in an electrolytic solution to correspond to the air compression pump 10. An electromagnetic coil 14 is excited by the electromotive force of the battery itself to attract a piston 11 to compress air in a cylinder 12 to send the air to the inner pipe 19 of the bubble pump 18. A reed switch 15 is turned off by the descent of the piston 11 to stop exciting the coil 14, to continue the vertical reciprocation of the piston. As a result, the electrolytic solution is lifted in an outer pipe 20 together with the air from the inner pipe 19 so that the solution is circulated. The staying portion of the electrolytic solution can thus be effectually utilized without manual operation.