This seems like a fairly basic thing but if you haven't ever done it before it can be a little confusing as to what the best approach is. Unfortunately I didn't have an extra set of hands to help take photos so I won't be able to show the two-handed action which is at the heart of a good soldering job but I can at least show the tools needed, explain some technique and show the end result. The example will be a deans connector soldered on to a lipo battery suitable for a 450-sized electric helicopter. This can also be applied to RC cars, planes, transmitters and any custom connector for any application.
First you will need a soldering iron and a holder. A medium heat one (30w) will work fine if you're using regular soldering mesh. If you want to use lead-free mesh, you may need a hotter iron but be careful with what you're soldering. Some soldering applications are very sensitive to the heat. I'm very careful when I solder Lithium Polymer battery packs. I don't apply heat for too long because that heat travels up the leads and I worry about too much building up in the pack.
Here is my soldering iron and stand. As you can see, it's from Radio Shack.
The next tool you will want is a set of helping hands. They are basically a set of alligator clips on some metal support which is held up by a heavy metal base. These are also available at Radio Shack and other hobby stores.
Now for the solder. I use standard small to medium sized mesh. The really thin mesh is hard to work with because you go through a lot of it when you're doing bigger connectors.
And finally - the battery pack that I will be soldering the connectors on to.
Start by placing the connector into one of the clips. Make sure you know which wire goes on which side before you do any work. Don't make the mistake of reversing them and having to redo it all! This is a deans connector and there is a standard polarity.
I like to presolder a little onto the connector. This makes it so that when you actually solder the wire on, it will have something to stick to and fill in the gaps underneat. To presolder, just heat the metal tab a bit then melt the solder on to it. You will be able to see when the solder bonds to the tab when it's just at the right temperature.
Normally you would make contact with the iron, the receiving tab and the solder all at once. I could only show one thing at a time because I had to hold the camera with one hand.
Now that the tab is presoldered, clip the lead of the battery into the other clip on the helping hands. Position it so that the lead rests right on the tab you are going to solder. You will need to orient it so that it's coming straight out because once it's soldered on, it will stay however you've positioned it. Don't forget to put the heat-shrink tubing on before you solder. You won't be able to add it after you're done.
Now for the tricky part. You need to apply heat to the wire, tab and solder all at once. You'll see the solder melt and absord into the wire and cover both the wire and the tab when you've got the heat right. Temperature control is key here. If it's too hot, it will all come apart right away. If it's too cold, it won't bond. This is the art and the part that you may need to experiment with to get just right. Just make sure that there is good solder coverage on both sides of the wire. There shouldn't be any gaps but it shouldn't have more solder than is necessary to cover it all.
Once you are satisfied with your soldering job, repeat these steps for the other wire. Again, don't forget to put the heat-shrink tubing on before soldering.
Here is what it should look like when you're done:s
You're supposed to use a heat-gun to shrink the tubing and no one will recommend using a lighter but if that's all you have, you can do a good job evenly applying the heat and shrinking the tube. Again, I don't recommend this but macguyver probably wouldn't have recommended anything he did either. Keep the flame away and move back and forth to evenly distribute the heat. Spin the connector around to the other side and you'll see when you've got it shrunk down enough.
And finally, a finished job!
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