Originally Posted by bikedoctor
You explained your soldering process to me and Ive been practicing but I cant get that really clean solder like you talked about.
Could you post it here?
Getting a good solder joint takes a lot of practice. I learned to solder building slot car chassis, the soldering we do in RC is child's play compared to trying to stick a piece of piano wire onto a thick brass plate or a piece of 1095 blue spring steel. The method I use is difficult to master, so I'll post it and another, easier way. As I remember, we were talking about soldering batteries.
Clean the ends of the cells by scrubbing with motor spray. Tin the ends of your battery bars, you want enough solder on them to make your joint-you won't add any solder when attaching them to the battery. You also want solder on the sides of the ends of the bars (clear as mud?) Place a tiny drop of acid flux on the battery ends where the bar will sit (only do one bar at a time, or the flux will dry out). Place the bar on the cells and put a little rosin flux on the top of the ends. Hold the bar down with an xacto or whatever, and put the tip of your iron on top of the battery bar end. The iron should have a tiny bit of solder on it to aid heat transfer. When the bar heats up the solder between the bar and the cell will melt, making a perfect joint with a minumum of solder. Inspect the solder joint to make sure that there is a little fillet of solder all the way around the contact point of the bar. Scrub the finished pack with motor spray to remove any trace of flux.
Scuff the ends of the cells with sand paper (like 3-400 grit), and scrub them with motor spray to remove any sand paper grit. Put rosin flux on the ends of the cells, and tin a spot a little bigger than the contact point of the battery bar. Tin the battery bars with enough solder to complete the joint.
Put some rosin flux on the ends of the cells and place the battery bar on them. Hold the bar down and place the tip of the iron on the top of the contact point of the bar (again with a little solder on it to aid heat transfer). When the solder melts between the bar and the cell, make sure the joint is liquid all the way around, then take the iron off. Check the joint for a good fillet of solder all the way around.
With both methods getting the right amount of solder in the joint is key, and that just takes practice. With the first method you can make packs that look like those Fusion packs that have almost no solder on the bars.
You don't need a giant soldering iron, just a good one. I use a 45watt Hakko #455 with the large chisel tip or an Ungar 50watt with chisel tip. With hot irons like these you should only have the iron on the joint for a few seconds. The acid flux is the kind you get at the slot car shop for building chassis, any kind of rosin flux will do.
Now go build about a hundred packs and you will be a pro!