Replacing a car’s battery is one of those regular maintenance items all car owners must deal with, but fortunately it’s an easy project you can do yourself at home.

Replacing Your Car Battery

Testing a car battery
Testing a car battery

No matter how well you treat your car, the battery isn’t going to last forever. Factors like heat and heavy use can affect the life of a battery, but most will last around three to four years. Thankfully replacing a car battery is a straightforward job and doing it yourself at home will save you tons in maintenance costs. Read on as we show you step-by-step how to replace your car’s battery.

Make Sure the Battery Needs to be Replaced

Jumpstarting a car battery
Jumpstarting a car battery

Knowing why your car won’t start is the first step in determining whether your battery needs to be replaced. Alternator problems, short circuits, or other electrical issues can prevent a car from starting or cause a dead battery. If not addressed, these issues will still run a new battery down causing the car to not start again.

It’s always a good idea to test the battery before replacing it. If you don’t own a battery tester, jump start the car and take it to the nearest auto part store where they can test your battery and also test the alternator and charging system to confirm that the battery needs to be replaced.

If the battery does indeed need to be replaced grab some gloves and safety goggles and these common car repair tools:

  • ratchet and socket (battery terminal and connector bolts are typically 5/16″ or ½”).
  • wrench and locking pliers
  • wire brush

Step 1: Locate the Battery and Disconnect the Battery Terminals

Person removing battery mount
Person removing battery mount

Before locating the battery, put the car in park, turn off the engine, and remove the key. Make sure the engine has cooled down before opening the hood to locate the battery.

Most car batteries are found under the hood of the car and mounted on a plastic or metal tray. Before disconnecting the battery, it’s a good idea to snap a picture of the battery in place to help you remember what everything looks like when it’s time to install the new battery.

All car batteries have two connection points for the cables, one being a black terminal for the negative charge, and the other being a red terminal for the positive charge. These terminals may also be marked with a + and – sign.

Always disconnect the negative cable first. Take a wrench and loosen the fastener that holds the negative cable to the battery post. After loosening the nut or bolt, rotate the cable connector gently while lifting it up from the battery terminal. Repeat these steps with the positive terminal.

Step 2: Remove the Old Battery

Old car battery removed
Old car battery removed

Now that the battery terminals are disconnected you are ready to remove the old battery. The battery will be secured with either a metal bar across the top or a metal clamp at the base. Loosen the bar or clamp and lift the battery out making sure to keep the battery upright and free from spills.

Step 3: Clean the Battery Terminal Posts

Corroded battery terminal post
Corroded battery terminal post

Over time the battery’s terminal posts corrode and now is a great time to clean them. Using a wire brush, scrub the battery cable ends and the battery terminal posts to remove any corrosion or dirt. The cleaner the posts and cable ends are, the better connection the battery will have.

Step 4: Install the New Battery

Installing a new car battery
Installing a new car battery

Position the new battery so that the red (positive) post matches up to the positive terminal. Lower the battery into the car and secure it with the bar or clamp you removed earlier.

Before you reconnect the terminals, it’s a good idea to apply a thin layer of anti-corrosive protection gel on the terminals. This prevents corrosion that can keep the battery from charging.

Always connect the positive cable to the new battery first. Push the connector all the way down on the terminal and tighten the bolt. Repeat these steps to connect the negative cable to the negative terminal.

Verify that the connections at either end of the battery are firmly held in place by gently shaking the battery. If the battery becomes loose, inspect the bar/clamp and the cables to ensure they are secured tightly.

Step 5: Start the Car

Person starting their car
Person starting their car

Close the hood of the car and start the car to test your work. Most new batteries come 75% charged and are ready to go immediately. Now give yourself a pat on the back—you have successfully installed a car battery!

How to Properly Dispose of the Old Car Battery

Car batteries have very specific disposal requirements, so you must take the proper steps to get rid of the old battery. It can usually be returned to the store where you purchased the new battery. Most states require retailers that sell new batteries to accept used ones for recycling. Just make sure to dispose of it as soon as possible as the batteries emit toxic gases and can leak.

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Ben Hill

Ben Hill grew up seeing his neighbor restore classic MG cars. Soon, Ben was building his own model cars. Then, in high school, he started restoring early model Ford Mustangs. The combination of art and science is what first drew Ben to the automotive industry. He appreciates the engineering and aesthetics of a well-designed vehicle. Ben earned writing recognition as a Kentucky Young Author of the Year. Today, he uses his bachelor of arts degree from Furman University, writing car reviews, comparisons, and about automotive financing.

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