Ultimate Electrics

Installing connectors

Setting up a new electric-powered model, and sometimes maintaining an older one, often requires installing new motor or battery connectors. In a previous column, I discussed some of the different types of connectors available, so this column will cover installing them. The various bullet connectors, such as Horizon’s EC and Castle Creations’ plugs, have a small cup on the end into which the wire is soldered. Blade or flat-plate connectors, like the Deans Ultra and Hobbico’s Star plugs, require soldering, too, but require a slightly different technique. Finally, the Anderson Powerpoles I’ve used for many years can either be soldered or, better yet, crimped onto the leads.

SOLDERING

Soldering requires a few specialized tools and supplies, and is made easier and better by having a few optional tools. First off, the requirements include a good soldering iron, solder appropriate for the task, and wire cutting and stripping tools. Optional gear is endless but can include clamps, hemostats, tweezers, or other ways to hold the wire and plugs in place while you solder them.

Since the discussion here involves power leads, I’ll assume fairly large wire is involved— say, from 14 to 10 gauge. For wire this size, I use an inexpensive Weller 40-watt soldering iron with a large wedge-shaped tip instead of an iron with a smaller, pointed tip. A tip with a larger mass will transfer heat quicker, melting

the solder but not heating up the material nearly as much. The solder I use is a rosin-core electronics solder. It’s a 60/40 tin/lead wire, .032 inch in diameter, which I’ve used for many years. It melts quickly and makes a good bond.

For cutting wire, I use a diagonal wire cutter. The one I currently have is from Zona, but any good-quality, sharp wire cutter will work. I use a stripper from Klein Tools, especially for small wire, and sometimes I’ll just use a razor knife to strip the larger power leads. Be careful if you do this, as it can cut into the wire strands.

For holding everything in alignment, there are quite a few “third-hand” devices available. I’ve tried several of them over the years, and the best I’ve found is the ProgressiveRC Soldering Stand. It has an optional second adjustable arm for holding things in position. It’s well designed and easy to use, and it stands up to the heat without being a heat sink, pulling heat away from the work. It has a clamp that’s made for various bullet connector sizes as well as a clamp designed for Deans and other oddshaped connectors.

Clamps, tweezers, and hemostats come in handy for holding parts in close contact while the solder cools. I also keep a stock of heatshrink tubing in a variety of sizes for insulating bullet connectors.

SAFETY CONSIDERATIONS

The solder I use melts at around 370°F—hot enough to cause a serious burn. To keep the hot iron out of the way, I keep it in a solderingiron stand, a weighted base with a springshaped holder for the iron. Weller puts a small stamped metal iron holder in the package with each iron. Always take the time to put the hot iron away in a safe place while preparing for the next connector.

When you solder plugs on batteries, take care not to short the leads. Our batteries store a tremendous amount of energy, and a short can cause serious burns or even a fire. Be careful working around bare battery leads while wearing jewelry—a friend shorted a battery with his wedding ring once, causing a bad burn and damaging the ring. When I put connectors on a battery, I do it from start to finish, one wire at a time. Strip the wire, install the connector, and be sure to insulate it before starting on the next wire.

SOLDERING BULLET CONNECTORS

All the bullet-style connectors, like Horizon’s EC as well as Castle Creations’ plain bullets and polarized connectors, use a similar procedure for installation. The main difference is in how the bullets are insulated, either by inserting them into a housing or applying heat-shrink tubing. Some housings require the wire to be passed through them before installing the connectors. Others, like the EC type, allow you to snap the connector into the housing after the soldering is done.

The process begins with cutting and stripping the wire. Be careful to strip only enough to fit the bare end into the cup, generally 1/8 or

3/16 inch. Tin the wire ends with solder by heating them with the soldering iron and then wicking solder into the wire. Tin the connector by heating it and melting solder into the cup. Then insert the tinned wire into the connector cup, and heat the barrel of the connector until the solder flows. Using a tool, like the Progressive RC Solder Station, to hold the parts in place as they cool helps avoid a cold solder joint. To finish, insulate the connector by snapping it into the housing or applying heatshrink tubing.

SOLDERING FLAT-PLATE CONNECTORS

The process for installing flat-plate style connectors is similar to bullet connectors, in that the wire still needs to be cut, stripped, and tinned, and the flat-connector end needs to be tinned with solder. After tinning, I hold the wire in place on the flat plate with a hemostat or tweezer and apply the soldering iron to melt the solder. With a 40-watt iron, it melts and flows fairly quickly. Hold the wire in place with the tweezer or clamp while the solder cools to avoid creating a cold solder joint from movement.

A point to remember with both of these plugs is that the insulation has to be put on the wires before soldering. With Deans Ultra, the insulation is heat-shrink tubing on each wire. Hobbico’s Star Plugs have a divided cover that snaps onto the rear of the plug.

ANDERSON POWERPOLES

Power poles can be soldered, but the best way to install them is to crimp them onto the wire. I overheard a conversation once that involved a guy who worked on the British Airways Concorde supersonic airliner. In a discussion about whether soldering or crimping was best, he responded that all the electrical connections on the Concorde were crimped, and that’s good enough for me.

I use a crimper from West Mountain Radio that has a die for 15-, 30-, and 45-amp power poles. I use the 45-amp size the most, as it fits up to 10-gauge wire easily. The process is simple: Strip the end of the wire to a length suitable for the connector, usually about

1/4 inch; fit the wire into the connector; and insert it into the crimper. Then squeeze the crimper until the ratchet releases. That’s it. Insert the completed connector into a housing to insulate it and the job is done.

BOTTOM LINE

Installing connectors for our RC electric-power systems is fairly easy to do with a little care and the right tools. Take care and do it carefully to reduce losses from poor connections.

This is the author’s completed Top Flite P-47 Razorback, ready to fly. It weighs 26 1/2 pounds and is powered by an AXi 5345/18 motor, 25x12 Fiala prop, and12S battery.

Tools for soldering connectors arranged around a ProgressiveRC Solder Station include (clockwise from top) wire cutters and strippers, tweezers, a 40-watt Weller iron, and a variety of hemostats and clamps.

Here the Solder Station’s adjustable clamp is used to hold the tinned wire aligned and in place as heat is applied to melt the solder. The clamp will hold everything in place as the solder cools to avoid a cold solder joint.

Tinning a stripped wire while it’s held in a clamp makes it an easy job. Apply heat to the wire end, then the solder. When the solder starts to flow, remove the iron and feed solder in as it wicks.

When the solder in the EC3 connector has set, but before the connector has cooled, insert it into the housing and use a small screwdriver to press it into the housing until it snaps.

Here, I’m preparing to clamp Anderson Powerpoles onto a new Venom Power battery. In addition to the 45-amp connector pins and housings, the West Mountain Radio crimper and small screwdriver are required as well as tools to cut and strip the leads.

The crimped pin is ready to insert into a housing. When installing connectors on battery leads, always work with only one wire at a time, making sure the other is always insulated to avoid shorting hazards.