CELLS WON'T STICK

Radio Control Car Action, Apr 2004 by Vieira, Peter

Q I've finally made the leap to building my own packs, but I'm having a heck of a time getting the pack to stay together. I solder the bars on, and everything looks good, but as soon as I flex the joint to test it, the bar pops off. The solder seems to stick to the cells OK, but the bars are a problem. I'm using a 4oW pencil-style iron, Deans battery bars and RadioShack 60/40 solder. Any ideas?

A It sounds as if your iron is up to the task (although at the low end of the wattage range), and that you've got the right solder. I think preparation is the key to solving your soldering problem. First, make sure that your soldering iron's tip is clean. If it's crusted with scale, replace it. Be sure to tin the new tip by letting a blob of solder melt on it for about a minute; then wipe the tip on a damp sponge. Next, make sure that the iron is getting hot enough. The solder should melt the second it hits the tip; if it doesn't, the tip isn't hot enough. Next, prep the cells by scuffing the ends with fine sandpaper, then dab with flux paste and melt a spot of solder onto each end. You should also tin the bars with solder. A good soldering jig can also make a big difference in the quality of your soldering job. Deans makes the best, and it only costs about $15.