LEAD-ACID BATTERY

A lead-acid battery () is provided with a lid (). An external flow passage () communicating with a communication chamber () through a vent hole () and communicating with a discharge port () of a lid () is formed inside the lid (). A compartment fence () continuously extending over the entire width of the external flow passage () is formed in the external flow passage (). A residual volume is larger than the volume of the communication chamber (), the residual volume being obtained by subtracting, from the total volume of a plurality of external spaces () divided by the compartment fence (), the volume of the discharge-side external space () closest to the discharge port among the plurality of external spaces.