How to Jump Start a Car


Whether it's because you left the lights on or your battery is old, most car owners will be faced with a dead battery sooner or later. If you ever find yourself in such a situation, this wikiHow may help you out.

Part 1
Checking the Battery

Checking the Battery on How to Jump Start a Car

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Check the headlights. Are they dim or bright? (Note that in some cars you will need to turn the ignition on to test the headlights). If they are dim, it's likely your battery is the culprit. If your headlights are bright, you do not have a dead battery and a jump start will not help. Ensure that the doors will unlock when you push the button on the key and/or try to open the door from the outside, the interior lights work, and the clock or GPS (if equipped) moves or powers on. Put the key in the ignition and see whether your dashboard lights up as usual. Test the stereo. In most cases, even with a low battery you should see some dashboard lights and get some sound out of the stereo. If you do not get a flicker out of your dashboard, you may have a problem with your ignition switch. Try to start the car. Does it turn over very slowly, or does it crank quickly? If it cranks quickly, you do not have a dead battery and a jump start will not help. If it cranks slowly, or not at all, you probably have a dead battery.

Part 2
Jumping the Battery

Jumping the Battery on How to Jump Start a Car

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On most cars, it will be near the front of the car on the right or left side, but on some cars the battery is located near the firewall between the engine and passenger compartment. In some cars the battery is located in the trunk. If unsure, check your car manual for location of the battery. Identify the positive and negative terminals. The positive terminal will be marked with a plus sign (+) and will usually have a red cable attached on it. The negative terminal will be marked with a minus sign (-) and will usually have a black cable attached to it.

Jumping the Battery on How to Jump Start a Car

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Park the car in such a way that the distance between both car batteries is as small as possible. Turn off the engine, radio, lights, A/C, fans and all other electrical components. Make sure that all of these things are off in the disabled car, too. Don't let the cars touch at all. If the cars are touching, jumping the battery can cause a dangerous electrical arc between the vehicles.

Jumping the Battery on How to Jump Start a Car

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Inspect batteries for cracks, leaks or other damage. If you find any of these things, do not jump start the car. Call a tow truck instead or replace the battery. It may be necessary to remove the disabled automobile's battery cables from the battery terminals and clean both cables and terminals. Use a stiff wire brush to remove all corrosion. Reconnect the cables to the battery terminals and jump the car. Remove any positive (+) red post protective covers if applicable.

Jumping the Battery on How to Jump Start a Car

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Like your battery, your jumper cables will probably have red and black cables and will have heavy-duty clamps to connect to the battery terminals. You must make sure that the red and black ends of your jumper cables never touch each other once they are connected to the batteries; permitting them to do so can result in serious arcing and/or damage to one or both cars.

Jumping the Battery on How to Jump Start a Car

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Connect one red clamp to the positive (+) terminal of the dead battery. Connect the other red clamp to the positive (+) terminal of the good battery. Connect one black clamp to the negative (-) terminal of the good battery. Connect the other black clamp to a piece of grounded metal on the dead car, preferably the bolt where the thick negative cable from the battery connects to the chassis. If this is not practical, look for shiny metal (not painted or oily) that is attached to the engine. Usually a nut, bolt or other protruding shiny metal will work. You may see a small spark when you connect to a good ground. As a last resort, you may connect to the negative (-) post of the dead battery, but this risks igniting hydrogen gas coming off the battery. Make sure none of the cables are dangling into the engine compartment, where they could be exposed to moving parts.

Jumping the Battery on How to Jump Start a Car

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Let it idle for a few minutes. Do not race the engine, but do rev the engine a little above idle for 30 to 60 seconds. You do this to charge the battery in the dead car, because the starter in the dead car will draw most of the required current (well in excess of 100 amps) from that battery, not through the cables. Common retail jumper cables are not built to pass the current required. Charging the dead battery is a must. If 30 seconds doesn't do it, try charging for the full 60 seconds by keeping the engine at a high idle. A good, clean connection between the battery cables and the battery terminals is essential.

Jumping the Battery on How to Jump Start a Car

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If it does not start, shut the engine off and disconnect the last connection temporarily while you slightly twist or wiggle each of the four clamps to help ensure a good electrical connection. Restart the working car again. Allow another five minutes for charging before attempting to start the disabled vehicle. If this does not work after a few tries, you may need to have the car towed or the battery replaced.

Jumping the Battery on How to Jump Start a Car

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Do this in the reverse of the order in which they were attached, and don't let any of the cables or clamps touch each other (or dangle into the engine compartment). Disconnect the black clamp from grounded metal on the dead car. Disconnect the black clamp from the negative (-) terminal of the good battery. Disconnect the red clamp from the positive (+) terminal of the good battery. Disconnect the red clamp from the positive (+) terminal of the dead battery. Replace any positive (+) red post protective covers if applicable. These covers help prevent accidental short circuiting the battery.

Jumping the Battery on How to Jump Start a Car

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Run the car above idle (slightly revved up with your foot on the gas) for five minutes and then on or above idle for 20 minutes before turning it off. This should give the battery enough charge to start the car again. If it does not, you probably have a dead battery or a dying alternator.

Part 3
Without Cables (Manual Transmission only)

Without Cables (Manual Transmission only) on How to Jump Start a Car

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Without Cables (Manual Transmission only) on How to Jump Start a Car

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[1]

Without Cables (Manual Transmission only) on How to Jump Start a Car

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[2]

Without Cables (Manual Transmission only) on How to Jump Start a Car

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[3] This is also known as key position two. The key is inserted and turned one step to the right. Turning one step further would start the engine, which you don't want to do.

Without Cables (Manual Transmission only) on How to Jump Start a Car

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Keep the clutch depressed. You'll start coasting down the hill or moving due to people pushing.[4]

Without Cables (Manual Transmission only) on How to Jump Start a Car

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0 km/h).[5] The engine should turn and start. If it doesn't, try depressing and releasing the clutch again.