Don't ask the question "How do I change a car battery" too late.

You jump into your car, turn the key only to find that your engine won't startIt's every driver's nightmare and sooner or later it will happen to youSo what can you do to make sure you don't get stranded somewhere because of a flat battery?

Auto batteries typically last only 2 to 3 years so it's no surprise that a flat battery is the most common reason why your car engine won't startThe trick is to recognise the tell tale signs of a failing battery and change it before it fails completely and leaves you stranded miles from home, late at night in the cold.

How to spot that your car battery is about to fail

Get to know what your engine sounds like when it's starting up because when your battery starts to get weak this sound will changeYour battery will struggle to turn your engine and it will take longer to startThese are signs that your battery will soon fail and you should replace it before it fails completely.

Changing your car battery isn't difficult

First go and get a replacement batteryThere are many different shapes and sizes available but make sure that you get one that's recommended for the make and model of your car.

Disconnect the car battery leads

Lift the hood or bonnet of your car and locate the batteryIt will have 2 thick wires connected to it, one at the negative end, usually a black wire with a '-' sign on the batteryThe other wire is the positive and will be colored redThe battery will have a '+' sign to indicate positiveWhen you put the new battery on you must make sure that the positive and negative wires are connected to the correct terminals.

Disconnect the negative wire firstYou will need a spanner or large pair of pliers to do thisMake sure that the wire is well away from the battery then disconnect the positive wire in the same way.

Remove the car battery

The battery often sits in a tray with a retaining strap or metal bar fastened with a simple nut and boltRelease the retainer and remove the battery from the trayLead-acid car batteries are heavy so you need to be careful when lifting it out.

Fit the new car battery

Place the new battery into the battery tray and secure it with the retainerMake sure that the fixings are tight and that the battery can't moveFit the positive (red) lead to the '+' terminal of the batteryTerminals are often tapered so you may need to tap the connector gently onto the terminal with a small hammer to make sure that it makes a good connection when you tighten the nuts that clamp the connector to the terminal.

Do the same with the negative (black) lead onto the '-' terminalWhen both terminals are tight and you've started the car to test it you should cover all the exposed metal parts of the battery leads with petroleum jellyThis will help to prevent corrosion and maintain the electrical connection between the connector and the terminal.

That's it, close the hood or bonnet of your car and you're doneYou won't need to ask, "How do I change a car battery" ever again.