How to jump start a car

There are few more frustrating feelings than coming out in the morning to find the battery in your car has gone flat.

If you’re prepared to wait you could call your auto club or roadside assistance service, but it can be an hour or more before the serviceperson arrives on a cold winter’s morning when demand is at its highest.

Instead of waiting you could jump-start your car and get on with your day without further delay. Jump starting a car is not that hard.

Locate the battery

Batteries most often let us down on a cold, miserable morning in the middle of winter, not the conditions for learning about jump-starting your car.

The battery is located in the engine bay on most cars.

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You'll also need to locate the donor battery of the other car.

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Before you find yourself in that situation pick up the owner’s manual and find out whether it is actually possible to jump-start your car. The battery is located in the engine bay on most cars, but there are a number that have it located in other parts of the car, such as the boot.

A car that’s got the battery in the boot will have a positive terminal in the engine bay for the specific purpose of jumping a car battery. Again, check the owner’s manual to help locate it.

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Inspect the battery?

Before attempting to jump-start a car with a flat battery, check it for damage, leakage or corrosion. Also check that the connections are clean and firmly attached. If you find anything, it’s best not to attempt to jump-start the car, instead call for help. Safety first.

What do I need?

The best way to revive a flat battery is to charge it using a car battery jump starter, but that takes time, something we rarely have when we’re in a rush to get to work. The alternative is to jump-start your car, and that can be done using a power pack, which is designed specifically for that purpose, or jumper leads/jumper cables using another car.

You can use jumper leads and another car to jump start your car.

Power packs can be bought from most automotive accessory stores and can be carried in your car to get you out of trouble whenever or wherever it strikes. They don’t need another car or mains power to work, but you do need to keep them charged so they’re ready to go when you need them.

If you don’t want to go to the expense of buying a power pack a set of quality jump leads will do the job nicely. The downside is that to use them you need another car to provide the jump start.

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Using jumper leads

Park the cars close enough together so the jumper leads reach from the donor vehicle to the flat one, but they should not be touching. Make sure both cars are in neutral or park, with the ignition off, and the handbrake applied.

Park the cars close enough together so the jumper leads can reach from the donor car to the flat one.

Connect the red clamp of the jumper leads (positive) to the positive (red) terminal on the donor battery, then connect the clamp on the other end of the (red) lead to the positive (red) terminal of the flat battery. If the flat battery is not located in the engine bay connect the other end of the lead (red) to the positive post provided in the engine bay for that purpose.

1. Connect the red clamp of the jumper leads (positive) to the positive (red) terminal on the donor battery.

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2. Connect the clamp on the other end of the (red) lead to the positive (red) terminal of the flat battery.

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3. Connect the black clamp of the jumper leads (negative) to the negative terminal on the donor battery.

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4. Connect the other end of the (black) lead to a metal earthing point, such as a bolt or a bracket in the engine bay, not the negative (black) terminal on the flat battery.

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Next, connect the black clamp of the jumper leads (negative) to the negative terminal on the donor battery, and connect the other end of the (black) lead to a metal earthing point, such as a bolt or a bracket in the engine bay. Do not connect it to the negative (black) terminal on the flat battery. If in doubt, refer back to your car’s owner’s manual. Check that the leads are not going to get tangled up with any parts that might be moving once the engine starts.

Check that the leads are not going to get tangled up with any parts that might be moving once the engine starts.

Start the donor car first and let it idle for a short period to stabilise before attempting to start the car with the flat battery. To avoid possible damage to the car with the flat battery from voltage spikes that can occur when jump-starting it, switch the headlights on on the car with the flat battery. The drain of the lights will help dampen any spikes that could occur.

After waiting a short period attempt to start the car with the flat battery. If it starts, leave it running for a few minutes to begin charging the battery. If it doesn’t start wait a moment or two and try again. If the jumper leads get hot do not try to start the engine, turn the ignition off and check that the leads are correctly connected before proceeding any further.

Once the engine is running on the car with the flat battery, remove the jumper leads in the reverse order that you connected them, making sure they don't touch each other or any metal surfaces. The car should then be driven for at least 30 minutes to charge the battery to a useable level.

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What if it won't start?

If the car won’t start even with a power pack or a battery from a connecting donor car, there is some other problem and you should seek expert assistance.

What if my battery goes flat again?

If the battery goes flat again, or regularly goes flat, there could be a problem with your car's charging system or the battery could be beyond recharging and probably needs replacing. Batteries are consumable items after all. To check the condition of your battery, go to a battery retailer who will happily do it for you.