How to Change a Car Battery

Your car’s battery is what makes everything in your car go. From your ignition to your radio, if you have a bad battery, none of them will work properly. A car battery, even the best one, won’t last forever. Five to seven years is the typical lifespan of a high-quality battery, less in areas of extreme heat and cold. When it’s time for a new one, you can change your car battery yourself. Here’s how to do it.

First, find out where your battery is. Yes, they're usually under the hood, but some vehicles put them in the trunk or under the seats. Some even put them in a place under the hood where you'd never find them by just looking around. The location is in your owner's manual, but a service manual for your vehicle is the best way to find out exactly where it is, especially if the battery is in a hard-to-reach position.

A factory service manual will tell you where the battery is, but, more importantly, it will tell you how to get to it. Invaluable for vehicles where the battery is under a seat or hidden away in a wheel well liner, and yes, that is a real place batteries can sometimes be hidden.

If the battery is hidden under some plastic covers or trim parts, a trim removal tool is the best way to remove those delicate parts without breaking anything. Especially important since there's a good chance your battery died in the cold and plastic parts are easier to break when they're frozen.

A leaking battery is dangerous. They are filled with sulphuric acid which can burn you and the car parts around them. Baking soda sprinkled on any wet spots around the battery can neutralize the acid. Rubber gloves can protect your hands and can also give you some insulation against accidentally shocking yourself with the battery.

Your car battery is probably held down by a small bracket. You'll need a small socket, usually a deep well socket, to remove the nut holding the bracket in place. A socket extension will come in handy as well.

Once you've removed the bracket, it's time to disconnect the battery. A battery terminal wrench is the best way to disconnect the battery. They're thin wrenches to fit into small spots, and a good one will have a ratchet mechanism so you can quickly spin off the nut or bolt instead of removing and repositioning the wrench every time. If you have room, a standard socket or combination wrench will work. Disconnect the negative terminal, the one that's marked with a "-" and is usually covered in black plastic, first. Then remove the positive red terminal. You should now be able to lift the battery out of the car.

Some car batteries will have a handle, but if yours doesn't, a battery carrier tool makes it easier to pick up and move your car battery. Remember that these are full of acid and lead and can easily weigh 40 lbs or more. Even a small battery is heavier than it looks.

Now that the battery is out, take a look at the tray where the battery sits. See any green fuzzies? That's corrosion, and it needs to be removed. Your battery tray can also be rusty, especially if the old one was leaking. Use some baking soda to neutralize the acid and then a wire brush to remove any corrosion. If there is rust, a wire brush followed by some rust-blocking paint should keep the corrosion from getting worse and rotting out your battery tray.

Before you install the new battery, use a battery terminal cleaner to make sure that the connections are clean. A corroded connection will give you poor performance even with a new battery. To help prevent future corrosion, battery terminal grease is a dielectric grease (meaning it will conduct electricity) that can protect the connection from th elements. It's not a must-apply, but it can be handy.

Installing your new battery

Feature Photo by By Tatiana Gekman/Shutterstock

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