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How To Crimp Battery Terminals: Eight Crimping Steps

Let’s look at how to crimp battery terminals below. 

If you replace your vehicle’s battery cables or lugs, you must firmly crimp the terminal lug to the wire. 

Corroded battery terminals are also problematic because they can cause starting issues.

And loose crimps can cause high electrical resistance on this battery connection when drawing high electrical current. 

This resistance can burn the wire or cause arcing. 

Loose crimps can also allow moisture into the joint, causing corrosion from the inside.

 So you have to redo the joint to create solid battery connections, and here’s how to do it.

Table of Contents

Why Crimp Battery Terminals?

Crimping is equivalent to creating a cold weld. When well done, a crimp can make the wire and connector barrel one solid piece of metal, creating a moisture, gas, and corrosion-resistant connection.

The alternative is to use soldering to join the two pieces. This process involves using heated metal to weld the wire to the terminal. 

While it will create a permanent joint, soldering degrades over time, especially when subjected to extreme conditions.

A battery wire neatly crimped to its terminal

A battery wire neatly crimped to its terminal

So crimping is better for attaching battery power cables to the terminals.

How To Crimp Battery Terminals Using a Crimping Tool

You will need the following tools.

  • Wire cutter
  • Wire stripper
  • Battery lug crimping tool
  • Color-coded heat shrink tubing (red and black)
  • Heat gun or flameless torch

Follow these steps to crimp the terminal using a crimping tool.

Step 1: Match the Gauges

Before getting to the crimping process, you must use a terminal that matches the wire’s gauge

Most cables and battery connectors have color codes, imprints of the gauge size, or stamps to indicate the diameter.

A wire stripper with multiple wire gauge markings

A wire stripper with multiple wire gauge markings

Step 2: Cut the Cable

Cut the battery cable on the end where you want to fit the terminal. Use a sharp wire cutter to make the surface straight and flush. 

You will need a heavy-duty wire cutter if cutting larger wire sizes (thicker than 2 AWG).

Step 3: Strip the Copper Cable

Each connector or terminal has a specific barrel length for inserting the wire. 

Strip the battery cable at a precise size that matches this hole depth. 

If too short, the connector won’t have a firm grip on the bare copper wire.

 And if it extends outside the barrel, you will end up with exposed copper strands that can corrode when exposed to moisture.

A close-up image of a wire stripper

A close-up image of a wire stripper

A good rule of thumb is to strip about an inch, but we recommend measuring the barrel depth in the connector. 

And use the correct wire stripper gauge for your cable size. Tiny ones or jacked necks can peel off some copper strands, reducing the wire diameter.

 A smaller diameter won’t fit perfectly in the battery lug, resulting in a weak crimp.

Step 4: Insert the Wire into the Connector

Fit the wire strands into the connector’s barrel and ensure all the strands are in to maintain the maximum diameter. 

This diameter determines the cable gauge, meaning the wrong size will affect the crimp quality.

Ensure the wire goes all the way in with zero exposure when it hits the end. If the stripping is too short, strip the wire again. 

But if too long, cut the wire to the correct length.

Step 5: Insert the Heat Shrink Tubing

Before crimping the wires, insert the color-coded heat shrink tubing over the wires. 

The red heat shrink tube should go into the positive terminal wire, and the black one into the negative terminal wire. 

This color coding is crucial if the cables have the same insulation color.

Colored heat shrink tubing

Colored heat shrink tubing

Optional Step: Apply Rosin Fluid

You can apply rosin fluid inside the barrel to create a sturdy electrical connection between the two metals, but this will require heating to boil the material. 

Rosin is the same material used in solder paste and flux to make the molten metal flow to create a solid connection.

Rosin in a jar

Rosin in a jar

Heating the fluid should occur after crimping, and you’ll need a butane torch. Heat the connector until the rosin bubbles.

Step 6: Crimp the Wires

Insert the wires back into the battery lugs, then use the battery cable crimping tool to press the barrels into the wires. 

But before that, set the crimping tool to the correct size using the die adjustment. 

This setting should match the cable gauge and connector style.

An adjustable battery terminal crimping tool with open hexagonal jaws

An adjustable battery terminal crimping tool with open hexagonal jaws

Place the connector’s barrel end in the crimping tool die, then press the handles.

 Most battery lugs have marked crimping spots, so you won’t have trouble crimping them in the right areas. And they usually need double crimping. 

Follow the markings to know where to press.

Make sure you fully crimp the connectors by pressing the handles down to complete the cycle.

A crimping tool with a terminal in its die ready for pressing

A crimping tool with a terminal in its die ready for pressing

Use a hammer with a flat nail punch or angle iron if you don’t have a crimping tool. 

Hammer the barrel hard several times to press it to the wire, then repeat the process on the other side (double crimping).

Step 7: Test the Crimp

Pull the wire from the connector to test the joint strength. A bad crimp will pull apart or feel loose. 

But a firm one will feel solid. You have to crimp again or redo the joint if loose.

Step 8: Apply the Heat Shrink Tubing

Push the heat shrink tube you had inserted earlier to the crimping location to cover the connector. 

These pieces usually have a melting sealant for waterproofing.

Use a heat gun or flameless torch to apply heat evenly on the tube’s outer surface until it shrinks and firmly wraps around the joint. 

Heat also activates the sealant, creating a waterproof seal.

A new battery with neatly crimped terminals

A new battery with neatly crimped terminals

How to Crimp Battery Terminals Without a Crimper?

As stated earlier in step six, you can hammer the terminal using a flat nail punch or angle iron to crimp the wire. 

But the process is easier if you can get your hands on a vise and a small steel ball or bolt.

Place the barrel between the jaws with the wire strands inserted in the terminal, then start clamping the vise. 

When the jaws almost bite the barrel, position the steel ball or bolt between the barrel and jaw. Ensure the jaw is pressing firmly against it.

After that, clamp the jaws tightly to press the steel ball or bolt to the barrel. This compression will crimp the terminal. 

Repeat the process for any other side marked for crimping.

Wrap Up

The battery terminal crimping process is straightforward if you have the right tools. 

But more importantly, you need these tools to create a solid quality crimp, so invest in the correct tools first.

 Contact us or comment below to request assistance. We’ll be in touch.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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