How to solder EC3 connectors for drones and rc airplanes
Clean and prep the soldering iron
If you’ve not used your soldering iron in a long time and it looks like a mess or you have a new iron, now is the time to clean and tin the tip. I use lead-free tinning flux to clean and re-tin my iron. Do not let the tinning flux come into contact with your bare hands because it is caustic and can cause severe burns.
Use a cotton swab and apply the flux to a cold soldering iron making sure to give the tip an even coat. Set the iron down on a hard surface (preferably one that cannot catch fire), turn the iron on, and let the flux melt.
Stay clear of any smoke and if you have fan or cross breeze, take advantage of it to blow the smoke away. When all the flux has melted away, wipe the tip clean using the wet sponge.
Over the wet sponge begin melting the rosin-core solder to the tip of the iron. Be aware that to get even coverage you’re going to use a lot of solder while tinning the tip. During tinning, periodically use the sponge or brass wool to wipe the excess solder from the iron. You’ll achieve desired results once you see a solid silver tip.
Soldering the wire leads and EC3 connectors
In this example, I’m going to solder male leads to a speed control that will then connect to female leads from a lipo battery. Long ago I decided to standardize my lipo battery leads to the EC3 female connections which was just a personal preference.
When soldering EC3 connectors you won’t need to strip too much of the insulation from the wire. 1/8 inch or 4mm should be sufficient. Only a small amount of wire needs to be exposed to make sure that the insulation is even with the top of each lead. Trim away a small amount of insulation at a time and check that you have the correct depth.
I prep each wire lead with a small dab of liquid soldering rosin. I feel this helps the solder to melt and flow more evenly through the wire braiding when I tin. Heat the surface by placing the soldering iron on the wire. Then touch the solder to the wire – not the tip of the soldering iron. Sometimes I need to place the solder right next to the tip of the iron to get the solder to start melting. Your tips are now tinned and ready to be soldered to the leads.
Once you hear that “pop” your connector and lead are locked in place and you’re done.
I clamp my EC3 leads into place using a set of Helping Hands. I add a drop of rosin into the cup of each lead to help with heat transfer across the lead and to help bolster solder adhesion. Hold the iron against the outside of the connector, letting it heat to temperature. Then slowly push the rosin-core solder into the cup of the lead and make a small pool of liquid solder. Keep the iron held against the lead to make sure the solder stays molten.
Grab your wire and quickly saddle it into the cup of the lead, wait a few seconds, and the solder will harden and your lead will be complete. Repeat this process for any other leads you have. The last part of the EC3 connectors is snapping the leads into the connector. You’ll need a very small flat head screwdriver to wedge into the tip of the connector to lock it place.
The connectors are labeled positive (+) and negative (-) so double-check and make sure you are locking the correct lead into the proper slot. Push the lead into the connector slot and listen to hear the lead “pop” into place. Once you hear that “pop” your connector and lead are locked in place and you’re done.