How to Jump-Start a Car

Learn how to get your battery going without electrocuting yourself. 

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There’s nothing quite like the feeling of hearing the sound of an engine cranking without the sweet, sweet ring of it roaring to life. This is when you know your battery is dead (or you have bigger engine problems) and it’s time to find a good buddy/stranger with a working car you can use to jump-start your dead beast. 

Safely jump-starting a car isn’t difficult if you know how to connect the right ends to the batteries, apply a little gas, and bribe anyone with a good car battery.

Safety

It’s important to remember that jumping a battery can be dangerous since you are dealing with electricity. Car batteries can also leak or release hydrogen gas that can catch fire or explode. Taking some safety precautions will help you minimize the risk.

  • Keep keys out of the ignition until you are ready to start the engine. 
  • Never connect red and black clamps together on jumper cables or a jump starter.
  • Remove any liquids or flammable items that may be near the car or starter. 

Things You’ll Need

To get your poor, dead car running again, you don’t need much in terms of equipment and tools. Here’s what you’ll need:

close up of a car during charge the battery
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  • Set of Jumper cables - something to transfer the juice to the dead battery. Jumpstarters often have these attached to the unit. 
  • Working car or jump starter - something with a good battery from which you can “borrow” some juice.
  • Dead car - i.e. your car.

Preparation

Depending on the length of your jumper cables, you will need to get the two cars close enough to span the distance between the batteries. Since the car with the dead battery isn’t going anywhere, position the good car into the optimal spot. If you do need to move the dead car, muster up some strength to move it around. 

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  • Position the cars nose-to-nose or close enough for the cables to reach each battery.
  • Make sure both cars are off.

Methods

The goal of jump-starting your car is to deliver enough juice to the dead battery to get the engine running. To do this, you can either use jumper cables and another car battery or a dedicated jump starter.

Jumping with Cables

This is the classic way of jump-starting a car: Connect the cables, apply the gas, and hope you don’t blow anything up. A pair of jumper cables are the most common get-out-of-dead-battery-jail-free card for automotive preppers since it’s small enough to keep in your car.

Connect the Cables

The first step is to get the jumper cables connected to the right posts on each battery. This involves some color matching. To connect the cables to the batteries:

  1. Lift and secure the hood on each car.
  2. Connect the red clamp on each end of the cable onto the positive terminal of each battery. The post will also be red and may have a “+” sign somewhere.
  3. Connect the black clamp on the good car’s side onto the negative terminal of its battery. This post will be black and may have a “-” sign somewhere.
  4. Connect the black clamp on the dead car’s side onto an unpainted, grounded metal part or surface. Somewhere on the vehicle’s frame is usually good enough. 
    • Do not attach the black camp to the negative post of the dead battery. Doing so can create sparks. 

Turn on the Good Car

Once everything is connected properly, you can have the driver of the good car turn on the engine and let it run for a few minutes. This will start to recharge the dead battery.

  • Start the engine of the good car.
  • Keep the engine running for several minutes.
  • Optional: Engage in an awkward conversation with the other person or enjoy the awkward silence.

Start Your Engine

After a few minutes, the battery should have enough juice to start the engine. 

  1. Turn on your car as normal. You can leave the good car’s engine running/charging the battery as you do this. 
    • If the engine starts, you have successfully jumped the car.
    • If the engine doesn’t start, keep the other car running for a few more minutes and try again.
  2. Remove the cables. Once you are ready to disconnect the cables, you should remove the clamps in reverse order: black clamp from the grounded surface, black clamp from the good battery’s negative post, red clamp from the dead battery, red clamp from the good battery. 
    • You can keep the batteries connected and the engines running to give a little more juice to the dead battery.

Jumping with a Starter

If you don’t want to rely on the kindness of others to get you out of a dead-battery pinch, a jump starter is a better solution over jumper cables. A portable starter is small enough to keep in a vehicle and does the work of the other car without the need for social interaction with others. 

Connect the Cables

Some portable jump starters come with attached cables, while others will have posts for normal jumper cables. In either case, you will need to connect the clamps to the right posts to complete the connection. To connect the cables to the posts:

  1. Lift and secure the hood on your car.
  2. If needed: Connect the jumper cables to the posts on the jump starter. Be sure to match the red clamp to the red post and black clamp to the black post. 
  3. Connect the red clamp onto the positive post of the dead battery. The post will also be red and may have a “+” sign somewhere.
  4. Connect the black clamp onto an unpainted, grounded metal surface. Somewhere on the vehicle’s frame is usually good enough. 
    • Do not attach the black camp to the negative post of the dead battery. Doing so can create sparks.

Turn on the Jump Starter

Once everything is connected, you can turn on the jump starter.

  • Start the jump starter. It should start charging the battery immediately.

Start Your Engine

After a few seconds or a minute, you can try to start the car with the jump starter continuing to run. 

  1. Turn on your car as normal. Try to turn over the engine for no more than five seconds. The starter or battery may overheat if you go longer.
    • If the engine starts, you have successfully jumped the car.
    • If the engine doesn’t start, wait a few minutes for everything to cool before you try again.
  2. Turn off the jump starter.
  3. Remove the cables. Once you are ready to disconnect the cables, you should remove the clamps in reverse order: black clamp from the grounded surface, red clamp from the dead battery. 
    • It’s a good idea to recharge the jump starter in preparation for the next time you need to jump-start the battery.

Tips

  • It’s helpful to make sure your battery is dead if you are experiencing engine problems. Signs include a slow engine crank, flickering lights, a warning light, or any power issues. 
  • If the dead car doesn’t start after a few attempts, try reconnecting the cables in the proper order. They may just be loose.
  • Try to inspect your jumper cables every so often for signs of damage. The cables should be free of splits and cuts.
  • Check on the charge of a jump starter every two or three months. 
  • If possible, try to find a car of similar size to jump-start your vehicle. Smaller vehicles can jump-start larger ones, but a similar match is more ideal.

FAQ

Q: Can I jump-start a hybrid?

A: Yes, using the auxiliary battery. This is likely a smaller 12V battery with the same posts as a normal car battery. Don’t try to jump-start the main battery. Given the smaller size, it’s unwise to use a hybrid to jump-start another car. 

Q: Must a jump starter be fully charged to work?

A: It isn’t necessary, but having a fully charged starter will give you the best results. Otherwise, you may unexpectedly run out of juice while trying to jump-start the vehicle.