If your car’s battery cables are too short, it can make jump starting or charging difficult. But before going through the hassle of replacing them, consider simply extending the existing cables first. With some basic tools and supplies, you can add length to your positive and negative battery cables, providing the extra reach you need.
Extending battery cables is a relatively straightforward DIY project. By carefully splicing in an additional segment of cable, you can give yourself the flexibility to more easily connect your battery to a jump source or charger. Let’s look at what’s involved in the process.
Table of Contents
- Understanding Battery Cable Extension
- Gathering the Right Supplies
- Step-by-Step Installation
- Testing and Troubleshooting
- Pros of Extending Battery Cables
- When to Replace Cables Instead
- Maintaining Your Extended Cables
Understanding Battery Cable Extension
Your car or truck’s battery cables connect the positive and negative terminals to key components around the engine bay. The red positive cable provides power, while the black negative cable completes the circuit.
Most battery cables are a standard length to fit the factory design. But over time, modifications, corrosion, or damage can make them too short to easily reach the battery. Rather than replacing the entire cable, you can cut it and splice in some additional length.
This involves cutting each cable at a suitable point, then splicing in a section of matching gauge automotive cable using copper crimp connectors. This joins everything electrically while adding perhaps 12-24 inches more cable.
Gathering the Right Supplies
Doing a neat, reliable job of extending battery cables requires having the right supplies on hand. Here’s what you’ll need:
- Replacement cable – Get enough 4 or 6 gauge multi-strand copper wire to extend each cable to your desired length. Red for the positive, black for negative.
- Wire crimp connectors – Adhesive-lined heat shrink style provides the strongest bond. Get large gauge sizes to match your cable.
- Wire strippers – A quality manual stripper or electric stripping tool removes just the right amount of insulation.
- Wire cutters – Sharp snips make precise cuts through thick cable jacket.
- Heat gun – Softens heat shrink tubing over splices for a rigid seal. A hair dryer can work too.
- Electrical tape – Helps insulate connections before adding crimp connectors.
- Cable lugs – Optional ends that crimp onto the new cable tail to aid terminal connections.
With the right supplies gathered, you’re ready to tackle extending those stubborn battery cables:
1.Safely Disconnect the Battery
Removing power avoids any risky shorts while working on the cables. Unbolt the negative terminal first, followed by positive.
2. Determine the Cut Point
Inspect the cables to decide where you’ll cut them to install the new longer section. Leave enough room for good splices.
3.Strip Cable Ends
Use strippers to remove about an inch of jacket from both cut ends, exposing the multi-strand copper inside.
4. Crimp On Lugs
Optional: Attach cable lugs to the new wire tails if desired, using a heavy duty crimper.
5. Twist Cables Together
Thoroughly twist the exposed copper strands of the two cut cable ends together to join the metal conductors.
6. Tape Connections
Wrap electrical tape tightly around each joined area to insulate it before crimping.
7. Install Crimp Connectors
Position connectors over each taped joint, ensuring full cable insertion. Then crimp firmly in place with pliers.
8. Apply Heat Shrink Tubing
Slide tubing over each connector. Heat carefully until it conforms snugly over the junction.
9. Repeat for Other Cable
Perform the full extension process in the same way for the positive or negative cable.
10. Secure Cables
Use zip ties to attach the new cable sections neatly out of the way along the route back to the battery.
11. Reconnect Terminals
With the spliced extensions complete, bolt the positive then negative lugs back to the battery.
Testing and Troubleshooting
Before driving, it’s important to test and verify your extended battery cable connections:
- Wiggle cables to ensure crimps are tight and heat shrink is sealed
- Check for exposed copper that could short
- Start the engine to confirm power is flowing properly
- Use a multimeter to check for voltage drop across connections
- road test the vehicle, ensuring normal electrical operation
If you experience dim lights, flickering, or other issues, recheck all connections. Loose crimps are most often the culprit. Heat and re-crimp if needed to restore a tight connection.
Pros of Extending Battery Cables
Taking the time to extend short battery cables offers some nice benefits:
- Avoid replacing expensive OEM cables
- Retain higher gauge wire and insulation
- Get custom fitment and length
- Easier battery access for maintenance
- Reach terminals from any angle
- Improve jump starting and charging capacity
The key is using quality parts and following solid wiring practices when splicing in additional cable length.
When to Replace Cables Instead
While extension can work in many cases, other times replacing old cables altogether is the better solution:
- If existing cables are cracked, damaged or corroded
- When more capacity is needed like upgrading to a higher CCA battery
- If existing cables are a lower gauge size and undersized
- To reduce voltage drop on an upgraded high load sound system
- To get a clean wiring setup on a heavily modified vehicle
Evaluate your needs, but splicing in some additional length is often the quick, easy and cost-effective way to go.
Maintaining Your Extended Cables
Even though they are tougher automotive cables, your extended battery cables still need periodic maintenance for longevity:
- Inspect for cracking or fraying of insulation
- Ensure terminals are clean and tight
- Check that crimp splice connections remain corrosion-free
- Lightly coat terminals with dielectric grease
- Avoid excessive bending or kinking of cables
- Protect cables from Elements with loom or conduit
With attention to periodic inspection and care, your extended battery cables can deliver reliable service life. This approach allows you to retain the high-quality OEM conductors while gaining the extra reach needed to easily jump start your vehicle or utilize battery chargers and maintainer
Extending battery cables is an inexpensive solution for gaining the additional length needed to access hard-to-reach battery terminals. Follow the outlined steps to safely splice in extra cable using adhesive-lined heat shrink connectors. Take precautions when working near batteries and be meticulous in your connections. The reward will be battery cables that now reach their terminals with room to spare. So analyze your needs, gather the materials, and give yourself the flexible battery connections your car or truck requires.