How to replace a car battery

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3 min read

Nothing blows your day to smithereens faster than a dead car battery. It’s the most common reason a car breaks down and is usually the easiest to prevent. Signs your battery is dying are dim headlights, it starts slower than usual, or a warning light on the dash (if you have it).

A flat battery isn’t a big deal, but if you leave it too long without running then you won’t be able to recharge and you’ll need to replace it.

Knowing how to deal with a dead battery is a useful skill to have in your toolbelt. And if you’re trying to sell an old car then you are guaranteed to get more bucks if it actually starts.

So it’s time to school up. Let’s take a look at how to replace a car battery.


Before you start goofing around under the hood there are a few safety tips to pay attention to. Cars run with 12V batteries so you’re not going flying if you get a shock, but it’s still best avoided. Old batteries can leak acid which can be irritating on your skin. Wear long sleeves, rubber gloves and safety goggles please!

Make sure the car is parked off road (or has the hazard lights on) with the handbrake on.

try a jump start

If the battery looks damaged or is leaking, don’t try a jump start. Otherwise the first thing to try is a jump start.

Connect the jump leads from your battery to another car (red cable to link the positives, and black to link negatives).

Start the working car and run it for a minute. Take a pause for a few minutes then try starting the dead-battery car. Assuming it starts, run both cars for ten minutes.

After that, disconnect the cables in reverse order and try to start your car. If it still doesn’t run, the battery needs replacing.

how to replace a car battery

First you need a car battery replacement. These cost between $50-$200 and you can get them online or from your local auto store. Make sure you have a wrench, ratchet and socket and locking pliers. Keep a wire brush and some battery cleaning gel handy.

Locate the battery terminals—there’s a red one (positive) and black one (negative). There might be a cover, if so remove it. Then disconnect the negative cable first by loosening the bolt and removing the connector. Do the same with the positive cable.

Remove the holding bar and carefully lift out the battery using the attached strap or using a battery carrier (keep it steady so as not to spill any acid).

Give the battery tray a quick clean with the wire brush and cleaning liquid and you're ready to slot in the new battery. This time, connect the positive terminal first followed by the negative terminal. Lock it back in with the holding bar and you’re good to go.

A dead car battery doesn’t need to be painful, but the cost of a replacement can be a shock (sorry!). If you can’t justify forking out, it might be time to cash in your car. Peddle will buy your car off you—battery or not—and you can put the money towards a motor with a bit more buzz.