PURPOSE: To achieve an easy but perfect seal at a connection portion extending through a partition wall in a lead battery by welding a male electode column and its corresponding female electrode column between cells and then urging a connector protrusion against a through-hole to tightly seal the latter.

CONSTITUTION: A through-hole 7 is formed through a partition wall 2 of a single- block type battery container. A welded portion 10 is formed by causing a connector protrusion 8 of a male electrode column 4 to extend through the through-hole 7 and then welding said protrusion into the connection hole 9 of an adjacent female electrode column 5. Around each of the protrusion 8 and hole 9 is provided a ring- like ridge 11. Both ridges 11 are pushed into the partition wall 2 when both electrode column 4, 5 are compressed, after said welding, by means of a pressing tool 14. The connector protrusion 8 expands radially toward the inner wall of the through-hole 7 and is then tightly urged against the inner wall, thereby to provide an excellent seal.