How to Change a Car Battery


 – Step 1: Locate the Battery Location

 – Step 2: Test your battery

 – Step 3: Buy the right battery

 – Step 4: Remove the battery

 – Step 5: Prepare the new battery

 – Step 6: Install the new battery

 – Step 7: Recycle the used battery

 Battery failure is a very easily recognizable failure. You enter your vehicle, turn the ignition key, and no light comes on.

 In 99% of the cases, the problem comes from the battery. A simple test with a voltmeter allows you to ascertain the source of the failure.

 If the failure comes from there, 2 solutions:

 – In the best of cases, it is enough to reload it.

 – But if your battery has reached the end of its life, you will have to replace it with a new one.

 This practical sheet explains how to change the battery.

1. Locate the location of the battery

 If you have the car maintenance booklet, refer to it. Otherwise, the battery is usually located in a visible and accessible area under the hood near the engine.

 – To do this, open the hood of your car and block it with the lift rod if it is not equipped with an automatic system.

 – Try to locate a rectangular box with two cables: one red and one black.

 Caution: Some batteries are located in the trunk or inside the fender and may be difficult to access. In this case, do not hesitate to get help from a professional or a seasoned mechanic.

 2. Test your battery

 An alternator problem can cause a power failure: the battery charging circuit is involved, but not the battery itself.

 So before buying a battery unnecessarily, you should check that the problem is there. To do this, test the voltage of your battery using a voltmeter.

 Caution: Remove rings, bracelets, and any metal objects that could cause a deadly short circuit if they come into contact with the battery’s plus and minus. Also, be careful that no wrench or other tool makes contact with both battery terminals simultaneously.

 – Put the multimeter in voltmeter mode, imperatively in continuous volt (symbol resembling the sign = and not resembling a wave ~).

 – Connect the red cable of the multimeter to the “+” terminal of the battery.

 – Connect the black multimeter cable to the “-” battery terminal.

 – The measured voltage should be between 12.5 and 12.7V.

 – If the value is below 11.7 V, your battery is empty.

 The first thing to do in this case is to try to recharge it. If recharging does not work, the battery must be changed completely.

 3. Buy the right battery

 Once you have located the battery location, read the information on the label:

 – the nominal voltage expressed in volts (e.g., 12 V) ;

 – the capacity expressed in ampere-hours (e.g., 75 Ah);

 – the starting power expressed in amperes (e.g., 400 A).

 Also note:

 – the location of the “+” and the “-“;

 – the model of your car;

 – the energy mode of your engine (diesel, gasoline, LPG).

 Go to an auto parts store or on the Internet with this information to choose the right battery.


 4. Dismantle the battery

Put yourself in a safe environment on a stable and flat surface with the parking brake (handbrake).

Good to know: if your vehicle is an ancient model, it can be equipped with a so-called “maintenance battery.” Wear protective gloves and goggles to protect yourself from the sulfuric acid in the battery that can escape. Wear old work clothes: if you come into contact with the battery, holes will eventually appear from washing.

When disassembling the battery, first locate the location of the “+” and “-” poles to make it easier to install the new battery, then :

– Disconnect your used battery, always starting with the “-“:

◦ Unscrew the bolt of the negative terminal.

◦ Slide the lug out of the terminal.

◦ If necessary, label the cable to identify the negative of the positive.

– Unscrew the positive terminal in the same manner.

– Unscrew all battery screws or bolts.

– Place them in a small box, so they don’t get lost.

– Lift the battery out of its place.

– Be careful not to tilt it (acid leakage may occur with maintenance batteries).

– Place the used battery next to your vehicle.

Caution: a battery can weigh up to 30 kg! If you have difficulty removing it, do not hesitate to ask for help.

5. Preparing the new battery

– Visually check the condition of the new battery terminals.

– Run very fine sandpaper inside both terminals or rub them with a wire brush.

– Blow on the terminals to remove all dust.

6 Install the new battery

– Place the new battery in place of the old one: be sure to put the “+” and “-” terminals on the right side!

– Tighten the screws and bolts that hold the battery in place.

– Connect the “+” terminal first by tightening the bolt with the wrench.

– Connect the “-” terminal in the same way.

– Finally, close the cover.

Note: It is preferable not to grease the terminals, as they may shift or even come off entirely due to vibration.

The car is ready to start.

6. Recycle the used battery

A battery contains highly toxic substances, so it should never be thrown in the trash!

To get rid of it, there are several possibilities:

– the waste disposal;

– the auto parts store.


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