How to Jump Start a Car Battery

how to jump start my car battery

A battery jump start using is a good way to get your car going using jumper cables which you can get from Amazon for between $16.00 and $38.00 (US). We recommend a good set for jumper cables because they carry a large amount of amperage and you want the jump to work without short circuiting. You will also need a car that has a good battery as well.

How Jumper Cables Work?

Jumper cable is a pair of large gauge wires capable of carrying a high amount of amperage from one battery to the other. This is done by using two large spring loaded clamps on either side of the jumpers, two negative and two positive which will connect two car batteries together.

Let's Get Started!

You will need to park the car with the good battery next to the car with the dead battery. This can be done nose to nose or side by side. You want the batteries to be close enough to one another so the jumper cables reach. It's a good idea to wear gloves and protective eyewear before beginning.

1. Lift the Hood on Both Cars: You will need to located the battery in each car. Nine time out of ten they are under the hood but sometimes they can be located in the trunk. Remove the terminal covers if any so the jumper cable clamps can get a good connection.

dead car battery

2. Inspect Jumper Cables: Gather your jumper cables and inspect them for any broken leads or open wires. Because these cables will be carrying high amperage they need to be of high quality and free from damage.

jumper cables

3. Separate the Jumper Clamps: You will be connecting the jumpers to the car with the dead battery first. The opposite end of the cables must be separated. If these ends are touching when you connect the jumpers to the battery there will be a short circuit and sparks which can cause the battery to explode. We don't mean to scare you, but inside the battery there are hydrogen gasses which a spark can ignite. It doesn't happen very often but it does happen.

separate jumper cable ends

4. Identify Positive and Negative Battery Terminals: The most important rule when jumping a battery is identifying the positive + and negative - battery terminals on both the dead and charged battery. The jumpers must be connected in the same polarity, in other words positive to positive and negative to negative. The positive terminal will be slightly larger in size that the negative terminal.

positive and negative battery terminals

5. Connect the Jumper Cables: Starting with the dead battery connect the jumper cables by squeezing the clamps of both the positive and negative clamps and attaching them to their respective terminals. Black for negative - and red for positive + which should be indicated on the battery. Once connected, wiggle the clamps to get a good connection on both.

connecting the jumper cables to dead battery

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6. Connect the Positive Jumper Only: Now you are ready to connect the charged battery to the dead battery. Again making sure the positive and negative terminals are understood connect the positive jumper clamp to the positive terminal which will be red or have a + sign near it. Take an extra second to make sure you are not hooking up the jumper cables backwards which can cause electrical system damage to both cars. Wiggle the clamp to get a good connection.

connect positive jumper only

7. Connect the Negative Jumper to Engine Ground Only: The final connection of the jumper cables will be to an engine ground only. The reason for this is because the final connection will make some minor sparks which can ignite hydrogen gasses inside the battery which can cause an explosion. This is also the reason for connection the charged battery last because the dead battery will be more prone to these explosive gases. For safety proposes find a metal bracket or bolt and make the final connection for the jumper cables. Wiggle the clamp to ensure a good connection. Also you want to be sure the cable and clamp are clear from rotating engine parts such as the fan blade or serpentine belt.

jumper to engine ground

8. Start the Car with the Good Battery: Go ahead and start the car with the charged battery this will enable the alternator and boost the voltage to the dead battery. It's a good idea to allow the engine to run for about 5 minutes before trying to start the engine with the dead battery. This is because the car that has the running engine is now charging the dead battery. Once the engine is running rest your foot on the accelerator to raise the engine's idle. This will help the alternator output more amperage.

start the engine of car with good battery

9. Jump the Dead Battery: Now you are ready to turn the key of the car with the dead battery and start the engine. Its a good idea to have anyone in the area to step back when cranking over the car with the dead battery. Once the car has started allow the car to run which will help charge the battery.  Sometimes a jumpstart will not work because the battery has shorted inside and needs replacement.

start the engine of the car with the dead battery

10. Disconnecting the Jumper Cables: Once the dead battery car has started it is time to remove the jumper cables. Shut the car with the charged battery off. Then remove the clamp from the engine ground to avoid sparks from near the battery. Remove the remainder of the jumper cable's clamps and then store them away for next time they are needed. Leaving them in your trunk or near the spare tire is a good idea because they will come in handy.

remove negative jumper cable first

Once the engine is running if the battery warning light is on it means the alternator could be bad and needs to be tested and then replaced if it is found to be not charging. If the battery is new but is repeatedly drained your car could have a draw which needs to be fixed so the battery can operate normally.


If you have any questions about jump starting, please visit our forum. If you need car repair advice, please ask our community of mechanics who are happy to help. Our service is always 100% free.

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