To reduce corrosion, improve corrosion resistance, and lengthen the service life even at a high temperature by forming a connecting part as the specific alloy composition.

The alloy composition of a pole formed in a cross sectional almost L-shaped inter-cell connecting conductor composed of a strap to connect mutual plate lugs having the same polarity, a strap and a lug plate, is specified. Alloy contains tin by 1.0 to 2.0wt.%, and is refractory to lead molten metal, and a melting quantity is reduced by lowering of a temperature in casing. At this time, lead-tin alloy contains one kind or two or mores kinds by 0.005 to 0.1wt.% among selenium, tellurium, sulfur and polonium deposited in lead alloy molten metal as a fine crystal, and contains tin in a residual part. This is specified in 1.0 to 2.0wt.% because when a tin quantity is little, strength of alloy reduces, and, in addition, the volume of an eutectic crystal to fill up a clearance between primary crystal groups reduces, and it melts in electric potential of a positive electrode plate when it is abundant.