Try using a quality liquid flux, like Trinity's solder flux. After cleaning/sanding the cell ends place a small drop of flux on the cells, then add another small drop to the top of the battery bars. Place the bars on the cells and with a BB sized drop of melted solder on the iron tip place the soldering iron tip to the bar. The solder should nearly instantly flow around the bar to the cell. Do not tin the cell ends. Tinning adds additional lead between the joint and increases resistance.
Last edited by SPC; 02-22-2006 at 05:34 AM.