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How to Replace Battery Clamps

Updated on June 17, 2016
Corrosion not only prevents proper electrical flow but will destroy your battery clamps.
Corrosion not only prevents proper electrical flow but will destroy your battery clamps. | Source

Replace battery clamps whenever they oxidize, crack or wear out and become loose after years of use. A car battery requires a tight and clean connection between each post and cable. Problems with the battery clamps not only can prevent proper power flow to your car circuits, but it can also cause your starter motor to overheat, wear down and keep the system from working properly. Battery clamp problems can also make it difficult for the charging system to restore battery power.

In most vehicle models you can replace battery terminals in about an hour or less. You just need a few common tools and a few minutes of work in your garage. Restoring a good battery connection will help all the electrical systems in your vehicle to function properly, prevent that you become stranded, and help extend the starter motor service life.

Use this guide to replace one or both terminals, as necessary.


How to save your car settings

Tools and Materials You'll Need

Disconnect the Battery Terminals

Clean the Battery Terminals

VIDEO - How to clean battery terminals

What You Need to Know About Battery Clamps

How to Replace Battery Clamps

Connect the Cables to the Battery

Quiz: Test Your Knowledge of Battery Clamps

How to Save Your Car Settings

If you want to preserve the car computer memory, and the settings for the alarm system or radio, use a computer memory saver, or connect a 9V battery to the car battery before disconnecting the terminals. Make sure to turn off all the accessories before connecting the device.

Tools and Materials You'll Need
Wrench or socket set
Diagonal cutting pliers or utility knife
Battery post wire brush
Baking soda and warm water, if necessary
Battery clamps
Heat shrink tubing, if necessary
Felt washers
Petroleum jelly
Carefully disconnect the battery terminals.
Carefully disconnect the battery terminals. | Source

Disconnect the Battery Terminals

1. Start by loosening the negative (black) battery terminal first—the one hooked to the battery post with the minus (-) sign. Use a wrench.

2. Finish disconnecting the negative cable from the battery.

3. Then, loosen and disconnect the positive (red) terminal.

4. Remove the damaged clamp with a pair of wire cutters or hacksaw. Use a small wood block as support while you saw the terminal.

5. Strip back about 1/2-inch of insulation from the end of the cable using a pair of diagonal cutting pliers or a utility knife.

Battery clamps should be clean and tight.
Battery clamps should be clean and tight. | Source

Clean the Battery Terminals

  • Clean up the wire strands on the cable end with a wire brush to restore their original shine.
  • Are the cable strands covered with a white or greenish substance? Soak the end of the cable for a minute or so in a solution of baking soda and warm water; and then brush off the corrosion.
  • You can use the same solution to clean the battery posts using a soft brush, if you see traces of corrosion as well.
  • However, if there's too much corrosion along the cable strands, you may need to cut the cable back. But don't cut the cable too short that it won't reach the battery post; otherwise, replace that cable—or cable set.

The following video will give you a visual reference for cleaning and protecting your battery clamps.

What You Need to Know About Battery Clamps

You can find replacement battery-cable clamps at most auto parts stores. The most common, and cheap, are the bolt-on battery terminals. However, this type provides a poor connection and is more prone to corrosion buildup. If possible, choose the battery compression terminal type, which makes a complete contact all around the end of the cable for better current flow. Some auto parts may sell OEM molded-type battery clamps, also a good choice, but you'll need a crimping tool for the installation.

How to Replace Battery Clamps

When replacing just one battery clamp, buy the one for the correct polarity, since they are not of the same size.

To install the bolt-on battery terminals:

* Loosen the new terminal clamp bolts, so the clamp opening is wide enough for the battery cable end to enter.

* Slide the stripped cable end into the clamp—and any additional wire grounds if you are replacing the negative battery terminal.

* Tighten the clamp bolts using a six-point wrench or socket.

NOTE: Some replacement battery terminals come with a copper crimp connector that wraps around the cable end instead (better than the bolt-on type terminals). To secure the cable to the terminal, just place the stripped end of the cable between the crimp connector tabs and, using a crimping tool—or suitable set of pliers—squeeze the tabs together firmly around the cable end.

* Repeat the procedure to replace the other terminal, if necessary.

To install compression-type terminals:

* Slide a piece of heat shrink tubing over the battery cable. Use red for the positive connection and black for the negative connection.

* Push the end of the battery cable into the compression nut.

* Hold the compression nut with a wrench.

* Start threading the clamp on the compression nut and tighten the clamp using a wrench.

* Slide the piece of shrinking tubing back over the compression nut and clamp base.

* Shrink the tubing using a heat gun, hair dryer or lighter to protect the connection against corrosion.

To install OEM molded-type battery clamps:

* Slide a piece of heat shrink tubing over the battery cable.

* Position the stripped end of the battery cable inside the clamp cavity.

* Use a crimping tool to lock the cable and clamp together.

* Slide the heat shrink tubing over the clamp base and cable.

* Use a heat gun, hair dryer or lighter to shrink the tubing. This will protect the connection against rust and corrosion.

Connect the Cables to the Battery

* Clean the battery post(s) using a battery post cleaning tool.

* Before connecting the terminals to the battery, place a felt washer over each battery post and then connect the cables to the battery.

* This time, though, start with the positive terminal.

* And then install the negative terminal.

* Disconnect the memory saver or 9V battery if you have one connected.

* After securing the terminals to the battery posts, apply a thin layer of petroleum jelly around the terminals and posts. Together, the felt washers and petroleum jelly will help prevent corrosion from creeping over the posts and terminals.

Replace battery terminals in a few minutes. When you replace damaged battery clamps, you form a good—and clean—path for full battery power to feed your vehicle electrical systems during engine start up. And plan on keeping it that way. Corrosion will attack the battery terminals, if acid and hydrogen gas begin to leak through. However, the precautions you took to protect the new terminals should keep corrosion at bay if necessary. Still, examine the battery terminals and around the battery case every time you need to pop the hood open. Clean up the terminals as necessary. This procedure only takes a few minutes and ensures that your car will have all the power necessary to operate properly.

Test Your Knowledge of Battery Clamps

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