Basic Knowledge of Quick Disconnects & Bullet Connectors

If you’re into anything from automotive repair, to hobby electronics, you’ve likely encountered quick disconnects and bullet connectors. Quick disconnects and bullet connectors provide reliable and easy separable electrical connections. In this blog post, we will discuss: what they’re used for, how to crimp them like a pro, and the pitfalls of what happens when you mismatch sizes.

What Are They Used For?

Quick disconnects and bullet connectors are types of crimp terminals that are designed for situations where you need to make and break electrical connections repeatedly, or when you need to easily remove a component. 

Quick Disconnects: These consist of two parts: a male spade terminal and a female spade terminal. The female terminal has a housing that slides over and grips the male terminal, creating a secure connection. They come in various widths to accommodate different applications and current loads.

Bullet Connectors: These terminals come shaped as a bullet (as the name suggests). They also come in a male and female pairing. The male bullet is a cylindrical pin, where the female bullet is a receptacle that the male pin can connect into. They are often found in automotive applications and are known for their compact size.

You will find various types of terminals:

Non-insulated quick-disconnects require only one crimp onto the wire
Vinyl insulation prevents incidental metal to metal contact that can cause shorts. This also requires only one crimp onto the wire.

Nylon requires two crimps - terminal to wire strands, terminal to insulation wire. It is best to use a crimper that performs both crimps at the same time.

Heat shrink does not require crimping, but requires applying heat to the tubing to shrink around and seal. This helps keep moisture out while ensuring your wire does not pull out of the terminal.

You can find Quick Disconnects & Bullet Connectors in:

Automotive: Connecting speakers, lights, sensors and relays.

HVAC Systems: Connecting control boards, fans, and thermostats.

Home Appliances: Internal wiring of washing machines, dryers and fridges.

Industrial Machinery: Control panels, sensors and actuators.

What happens if you mismatch sizes?

It is crucial to ensure that the male terminal and female terminal match. Failure to do so can lead to a range of problems, from minor annoyances to serious safety issues:

- Loose connectors can disconnect the wiring or voltage drop
- Forcing connectors to fit can potentially damage both terminals
- Both of these issues can create high-resistance paths for the current, leading to heat build up, which can melt the insulation, damage adjacent components or lead to severe cases (ex: a fire)

Always ensure your quick disconnects and bullet connectors are appropriately sized for both the wire gauge you are using (the barrel size for crimping) and the mating terminal (the spade width or bullet diameter). When in doubt, measure both parts or consult the specifications of the components you are connecting. A proper, snug fit is essential for a reliable and safe electrical connection.