The Moroso impact battery wire crimp tool is a very simple device that creates professional looking crimps in even the largest diameter automotive battery cables. We’ll show you how it works. (Image/Jeff Smith)

As with most things in life, there’s a right way and a wrong way to do things. That idea extends even to crimping battery cables. This story will illustrate how to perform this simple task the right way.

Moroso has designed an impact wire crimp tool that makes it quick and easy to crimp those soft copper battery cable terminal ends directly to a multi-strand battery cable.

While considered a battery cable tool, the Moroso instructions say that this crimping tool can be used for all wire sizes from 16 gauge all the way up to 4/0 cable. We’ve included a chart at the bottom of this post that lists all the different cable and wire gauge diameters to make the AWG ratings a little easier to understand.  

New to automotive electrical wiring? Here’s a handy primer: Automotive Wiring 101: Basic Tips, Tricks & Tools for Wiring Your Vehicle

Using the Moroso Impact Wire Crimp Tool

The fact is, it will take us longer to describe the action here than it does to actually perform the crimp. It’s that easy.

At the back of the Moroso crimp tool is a small pin. The ram is spring loaded and if you pull up on the pin, there’s a ledge that will allow the striker to be locked in the up position.

On the backside of the tool is a small lift pin that can be used to raise the ram and lock it in place in the upward position to make it easier to position the cable end. (Image/Jeff Smith)

Start by stripping back roughly 5/8 inch of insulation from the end of the battery cable. Next, position the copper terminal in the V-shaped base under the ram. To give the crimp a professional appearance, it’s best to make the indent on the bottom side of the terminal. This creates a clean looking top surface.

Trim the wire insulation roughly 5/8 inch and test fit the cable end on to the cable to make sure the wire achieves maximum depth into the cable end. Place the cable end upside down so that the imprint will not be visible and give the finished crimp a more even appearance. Make sure the shrink tubing is in place before completing the crimp. (Image/Jeff Smith)

If you are going to use a shrink wrap around the cable end, be sure to slide the wrap over the cable before making the crimp.

With the copper fitting end nestled in the tool, lift up on the pin in the back of the tool so the striker locates the middle of the sleeve on the copper terminal. Now insert the battery cable into the sleeve and make sure the cable fits as deeply as possible.

We found hitting the ram portion a couple of times ensures a solid connection. The tool can be squeezed in a bench vice to achieve the same result. (Image/Jeff Smith)

Now strike the top of the tool with a large hammer. This may require more than one hard blow to complete the crimp. It’s best to locate the tool on a solid surface like the edge of a work bench or even a concrete floor. The tool has a small scale on the side of the ram that indicates crimp sizes but we found it hard to read—but it is there if you want to use it.

The crimp tool can also be compressed in a bench vise if wailing on things with a large hammer isn’t your style.

After a couple of hard blows, inspect the crimp and then slip the shrink tubing over the crimp and heat it in place. The instructions claim this tool can also be used to crimp wire down to 16 gauge but after experimenting we prefer hand-held crimping pliers for smaller gauge wire.

We slid the shrink wrap over the end of the cable and applied heat to finish the job. This literally takes less than a minute if you have all you tools at hand. This is a simple job that produces a professional looking cable end. (Image/Jeff Smith)

That’s it—you’ve now performed a professional crimp that will last years. The job is simple, easy, and will deliver low resistance amperage flow to the starter motor.

That should make both you and your starter motor happy!

Wire Gauge to Wire Diameter Comparison Chart

Wire Gauge
Wire Diameter

Moroso Impact Wire Crimp Tool Parts List

Author: Jeff Smith

Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. In 1987, he assumed the role of editor for Hot Rod magazine before returning to his first love of writing technical stories. Since 2003, Jeff has held various positions at Car Craft (including editor), has written books on small block Chevy performance, and even cultivated an impressive collection of 1965 and 1966 Chevelles. Now he serves as a regular contributor to OnAllCylinders.