GOLD BULLET PLUGS - These gold-plated, single-pin connectors from Hobby Lobby are excellent for connecting motors and speed controls but can be used anywhere in your power system. They do not include housings; you make your own. Heat-shrink tubing is applied over the length of the wired, joined connectors and then slit around the joint so that you can unplug and plug. These are often referred to as “gold bullet” connectors (weight of additional heat-shrink tubing to cover joined connectors included). Left: Weight (2 pair): 3.1 g; Current Max: 70 amps; Part No. JEC001 (3 female); price—$4.20; Part No. JEC002 (3 male); Price—$6.20

The remaining three connectors, left to right, have recommended current ceilings of 40, 25 and 10 amps, respectively. Largest to smallest: Part No. MJ21031; Weight (2 pair): 5.3g; Price (3 sets)—$ 9.80; Part No. MJ21021; Weight (2 pair): 2.8g; price (3 sets)—$9.40; Part No. MJ21011; Weight (2 pair): 1.2g; price (3 sets)—$ 9.00
TAMIYA CONNECTORS - The Tamiya 7.2v 2-pin connector is available under a variety of brand names and has been a standard in the RC car market for decades. These connectors are primarily used in toy and hobby grade RC cars and boats, and have pins that are crimped but not soldered to the wire leads (not as reliable over the long term as soldered leads), and are not recommended for high-current airplane applications. They do come stock on some RC car speed controls that are rated for very high amperage, but that is a different operating environment characterized by short motor runs in car races lasting only a few minutes. The DuraTrax battery-connector set shown comes with leads pre-installed. Weight (pair): 4.7g; Recommended (conservative) Current Max: 20 amps; Part No. LXGG99; price—$4.00 (pair).


DEANS ULTRA PLUG - The Deans Utra Plug, whose pins use both gold and silver plating, is widely used for higher current applications. Deans notes that they have less resistance than an equivalent length of 12-gage wire. The battery side of these 2-pin plugs is female; the speed control side has spring-loaded male pins. Weight (m/f pair): 4.7g; Current Max: 100+ amps; Part No.1300 (m/f pair); Price—$3.75; Part No. 1301 (4 fm plugs); Price—$5.95
JST CONNECTORS - Referred to as “JST,” “GWS-like” or “BEC-style” connectors, these are available from a wide variety of sources with pre-installed, pre-tinned wire leads; they are used to power smaller models whose motors draw under five amps at full throttle. Left: Great Planes Electrifly (2) male pin set—Part No. LXWW67, Price—$2.79 (pair). Middle: Great Planes Electrifly (2) female pin set—Part No. LXWW68, Price—$2.79 (pair). Weight of one mail/female connector pair: .8g. Top right: Electrifly male charger adapter (Part No. LXWV18, Price—$2.79) and female charger adapter (Part No. LXWV19, Price—$2.79). These include 24-gage wire.
If your model is drawing upwards of five amps, note that these connectors are available from Maxx Products Int’l (MPI) with 18-gage wire leads.
GOLD STECKER PLUGS - Top right: Kavan polarized, 2-pin “Gold Stecker” connectors are heavy-duty solutions for sport and high-performance, competition applications (sold by Hobby Lobby). This connector has a uniquely solid feeling when you plug the connectors together, and will take wire up to 4.7mm O.D. Weight: (2) – 8.4g; Current Max: 40 amps continuous (much higher short term current); Part No. HLFK6326; Price—$ 7.90 (pair)

Left: Smaller Speed 400 2-pin connectors: Weight (1): 1.8g; Current Max: 20 amps; Part No.: HLFK4013 (red), HLFK4014 (yellow); Price—$3.60 (one plug with M/F pins)
MULTIPLEX 6–PIN CONNECTORS - The Multiplex 6-pin connector can dedicate three pins to positive and three to negative with a recommended current ceiling of about 50

amps. An interesting application is for glider wings: a single connector can be used to wire four servos: two pins route power to all servos and the other four connect signal wires running from the radio to the servos. Weight (pair): 2.7g; Current Max: 50 amps (two-lead config); (Part No.s 85213 and 85214). Price–$4.00 (pack of 3 male or 3 female)

GRAUPNER 6-PIN CONNECTORS - Graupner (distributed by Hobby Lobby) markets similar connectors that are orange colored. Part No. GR2978 (male), GR22979 (female); price—$2.40 each

HOBBY LOBBY ULTRA LIGHT MICROS - Bottom: Ultra-light, polarized micro connectors from Hobby Lobby can handle up to five amps. Weight (pair): .3g; Part No. POT015, Price--$5.20 (pack of 5)
RTF AIRPLANE PLUG - The smaller, white 2-pin connectors at top have appeared in a variety of ready-to-fly airplanes manufactured in China. They are smaller than the Tamiya-style connector (shown for size comparison), are typically found in smaller ships that draw under 10 amps at full throttle, and weigh just under three grams a pair.

DEANS MICRO PLUG - The Deans 2-pin Micro Plug connector series is designed for slow and park flyers, and is part of a new micro plug line that will eventually replace previous Deans micro connectors. They are available in polarized versions with red or black housings. A ridge on the rear of the housing allows for easy connection and disconnection. Weight (pair): .9g; Current Max: 15 amps; Part No. 1221 (black), 1222 (red); price—$1.55 (pair)

Connection force. This consideration applies mostly to small models, where a sudden jerk on a connector while disconnecting it can apply enough stress on a model to break something. On the other hand, you don’t want to have the connection so loose that as you fly, it can vibrate loose, possibly causing a loose connection and loss of control. Also, the tighter the connector (up to a point,) the more efficient the electrical connection.

Polarization. Many connectors have a plastic tab or a pin arrangement that allows them to be connected only one way. Such a connector is said to be “polarized.” Many RC components can be destroyed if a connector is plugged in the wrong way. If a motor is wired the wrong way, it will run backwards. There are various approaches to ensuring polarization; some connectors (e.g., Power Poles) are color coded but mechanically identical; others are physically incompatible if polarization is reversed.

Safety. Electric model plane batteries store a lot of energy. If the plus and minus terminals or the two wires of such a battery touch, or if they both touch the same piece of metal, you have created a “short circuit.” Such an accident usually causes intense and immediate heating, which can melt wires, create a fire, and cause damage or injuries. The safest connector type for batteries has both pins hidden inside a plastic case, i.e., has no exposed metal contacts.

Battery connectors. Of all the connectors in an electric model plane, it is most important that the battery connector be polarized. The battery connector should mate only with the battery input connector of the ESC [the motor connector to the ESC should be a different type]. We recommend that you never use the same connector setup for the motor, otherwise you might plug the motor directly into the battery, in which case the motor would suddenly and uncontrollably be at full throttle. Moreover, by using different connectors for battery and motor, you will never accidentally plug the battery to the wrong side of the speed control, which would damage or destroy the speed control.

Current capacity. All connectors create resistance and some form of losses in the form of heat. If you are using the right connector, the heat is so slight that you will never notice it. However, if the connector is too small or if the contacts are not sufficiently clean, a connector can get hot enough to damage itself, the aircraft, and you. 

Even if the heating doesn’t cause any damage, you are wasting battery power and losing duration. This means shorter motor runs and less thrust. Every connector has a recommended maximum current, which is rated in amps (A) or thousandths of an amp (milliamps or mA). The larger the contact surface of the connector, the more current it can carry.

Compatibility. If you fly with friends or a club, and use equipment and batteries that are similar to those used by others, then there is some advantage to using whatever connector setup that is used locally. At our field, it is quite common for one flier to offer the use of his or her charger or battery to another. If the charger and the battery don’t have matching connectors (or if suitable adapters or “patch cords” aren’t available) this is hard to do.

Ease of attaching wires. Some connectors are available only with wires pre-attached, and you are stuck with the kind of wire and length provided. With others, you choose the wire you want to use and cut them to the desired length. Wires are typically attached to the pins in one of two ways– crimping or soldering. Crimping. The first, used mostly by factories, is crimping, where tabs on the pin are folded and crushed on the end of the wire. This process is used commercially because it is fast and — if done properly — makes a long-lasting and sturdy connection. There are home crimpers for some connectors (each design of connector requires a custom crimping device), but if wire of the wrong size is used, or if too little or too much pressure is applied, the connection may not be mechanically and electrically secure.

Soldering. The second method, used both commercially and by hobbyists, is soldering. It, too, must be done properly; however, a $10 soldering iron will work for any brand or kind of connector. A properly made solder joint made with quality solder is good for decades, and is mechanically strong.

Some connectors have a hollow tube (the “solder pot”) into which you slip a wire before soldering it (e.g., Astro Zero-Loss, Duratrax Power Poles). These are easier to solder to than those for which you have to solder to the exterior of the solderable part of the pin (e.g., Deans connector).

Availability. The major connector brands shown in this article are widely available from a variety of sources. Check to see what your local hobby store carries.

Durability. A connector works by making contact between two conductors. The material these conductors have on their surface is very important.
If you want only the best: Best of all are connectors with gold plating, such as those from Deans, Astro Flight, Hobby-Lobby, and some others. Gold does not oxidize, and gold-plated connectors can last for years. Very little gold is used, so gold-plated connectors are not much more expensive than other kinds.
Some connectors, which have a tin or steel surface, conduct electricity very poorly as they age. The surface oxidizes and combines with the water and other chemicals in the air to make a non-conducting coating, and dirt gradually accumulates as well. A good connector has a “wiping” action that can clean the surface somewhat, but that can help only so much. I have had such connectors, which, while satisfactory at first, eventually got hot and melted in
the air.

We also highly recommend connectors with silver plating. Silver does oxidize, but silver oxide is conductive, so connectors such as the Anderson Power Poles (also branded under a number of other names) do not degrade much with time.

Mechanical strength. Smaller connectors are naturally more delicate than larger ones, but within a particular size range, some are sturdier than others. Whether this is important to you depends on your operating style. Are you impatient, tugging on connectors by their wires instead of properly pulling them out by holding on to the plastic housing? Do you carefully line up pins before making connections, or do you just push harder if the connectors are not going together easily? The more you use brawn, the more important the mechanical strength of the connector—almost any connector is plenty strong if you use care and common sense in handling it.

Special features. Here are some examples: The single-pin Sermos connectors have tabs so that they can be assembled into multi-pin connectors in many ways. This feature can be used to create connector pairs that cannot be incorrectly mated. Deans connectors are available in a wide range of configurations that give you many choices for creating mistake-proof connections. The smaller JST (GWS-like) connectors are among the lightest available and are well-polarized.

SUMMARY

Connectors are simple enough; just pairs of pieces of metal in plastic housings that allow you to connect and disconnect electrical components from one another. Armed with a little knowledge, you can choose and use connectors more effectively and with confidence.