LEAD-ACID BATTERY

A current collector included in a positive electrode plate and/or a negative electrode plate of a lead-acid battery has a frame rib and inner ribs inside the frame rib. The frame rib includes an upper element, a lower element, and a pair of side elements coupling these elements. The inner ribs include a longitudinal rib, which extends in a first direction from the upper element toward the lower element, and a transverse rib. A striped pattern of a metallic fibrous structure is seen in each of a first cross-section perpendicular to the first direction of the side element and a second cross-section of the longitudinal rib. An outer peripheral region of the first cross-section is made up of a first portion in which the fibrous structure extends along a contour of the first cross-section and a second portion except for the first portion, and the second portion is made up of a 2A portion disposed inside the frame rib and a 2B portion disposed outside the frame rib.An outer peripheral region of the second cross-section is made up of a first portion in which the fibrous structure extends along a contour of the second cross-section and a second portion except for the first portion. A percentage R1 of a length of a contour corresponding to the 2A portion to a total length of the contour of the first cross-section is less than 25%, and a percentage R2 of a length of a contour corresponding to the second portion to a total length of the contour of the second cross-section is less than 50%.