This tutorial offers step-by-step details on soldering 8mm bullet connectors to wires. These bullet connectors are typically used in high-powered ESC such as Mamba XLX2 and powerful brushless motors such as TP 4070 motors that support high continuous current use.
To demonstrate this tutorial, we shall solder three bullet connectors to three 8 AWG gauge wires of TP 4070 brushless motor.
What is 8mm Bullet Connector
8mm bullet connectors are wire connectors that could carry continuous high current. They are called bullet connectors thanks to the bullet shape of the male variant with an outer diameter of 8mm. A common misnomer is to name these connectors “banana plugs” because the male variant doesn’t look close to a banana.
They also have anti-spark protection, offering greater protection against electrical arcing during connections. They support continuous current load of up to 150 Amps and boasts a peak current rating of 300A. The contact material is usually made from gold-plated copper. QS8 connectors come with bullet connectors on the inside.
Things You Need
- 8mm male or female bullet connectors
- Soldering iron
- Solder
- Solder flux (optional)
- 10mm diameter heat shrink
- Plier, vise grip or soldering third hand
Soldering the Wire
You should apply some solder on the ends of the wires that you will connect to the connectors. This will help in bonding.
Firstly, ensure the wire end is clean from dust or dirt. You may apply solder flux to clean ii by removing oxides and impurities. Then, apply heat to the wire end with a hot soldering iron. The amount of time to heat up the wire end depends on the gauge of your wire. An 8 AWG gauge wire typically needs one minute. You may test the heat by melting some solder on the wire. Hotter wire allows solder to stick better.
You need a good amount of heat on the wire to have a smooth solder surface.
Once the wire is hot enough, apply some solder at the end of the wire. Also apply a small amount on the side of the wire, enough to ensure it can be inserted into the bullet connector’s end.
Soldering a Bullet Connector
Ensure the connector is clean from dust or dirt. Then, secure the connector using a vise grip, plier or soldering third hand. Ensure the grip is just tight enough to hold the connector in place.
Apply heat to the wire connection end with a hot soldering iron for approximately one minute.
Once it is hot, melt some generous amount of solder inside. Do not melt too much solder on the connector because it might spill out when you connect the wire.
While the solder is in molten state, insert the wire with the soldered tip into the connector and hold it in place until the solder cools and harden.
Ensure that you place the wire straight and centered into the connector.
Once the solder has hardened, you may apply more solder around the wire and bullet connector to ensure the connection is nice and secure. You may also apply more solder inside the side holes of the connector.
Applying Heat Shrink
Cut out some 10mm heat shrink and insert it into the connector and wire. Make sure that the heat shrink covers any exposed wire and the rim of the bullet connector. The main purpose of the heat shrink is to isolate the bullet connector from other conductive surfaces. It also makes your work look good!
Use a lighter and slowly burn the heat shrink until it wraps uniformly around the wire and connector. The flame should not touch the heat shrink. Don’t over do this as the heat shrink might get charred.
The Result
Repeat the process above with all your wires and you will eventually obtain a result as shown below.
