How to jump-start a car: expert method and tips

jump-start a car Jumper cables

Car engine with jumper cables, close-up

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Carrying a set of jumper cables can help you to help another driver – or vice versa. It’s usually fairly simple to jump-start a car, but it’s serious business and you have to do it right to make it safe. Every year, people are severely injured while trying to help another driver with a “jump.” Print this article and put it in yours to help out when you need to jump-start a car.

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Jump-start a car: the steps

  •  Make sure both have the same voltage (most batteries have 12 volts) and the same polarity (both have a negative mass). You can read this information in your manual in your glove box.
  •  Pull your cars close enough to each other to connect the cables, but never let the vehicles touch. This could cause a short circuit.
  • Turn off the ignition switch, the lights and accessories in both cars. Make sure that the vehicles are parked or neutral and that the parking brake is set. Wear safety glasses.
  •   Do not smoke. Sparks near a battery can cause an explosion.
  •   If the weak battery is frozen, do not try to jump it! It could explode. You can tell if it’s frozen by looking through the inspection cap to see if the water is frozen. One or more sides of the battery case bulge when frozen.
  •   Make sure you can identify the positive and negative terminals of both batteries. Also make sure you have enough room to clamp on the cable clamps. The positive connector is most likely connected to the car’s start / charge system with a red cable that has a plus sign. The negative is connected to the engine of the vehicle and usually has a minus sign.

How to use the jumper cables and start the car

1. Connect the positive (red or yellow) cable to the positive terminal of the weak battery. Make sure that the other end does not touch any part of the engine or body or that a dangerous spark is generated.

2. Connect the other end of the positive cable to the positive pole of the good battery.

3. Connect the negative cable (black) to the negative pole of the good battery.

4. Clamp the other end of the negative cable to a clean metal part of the motor (such as a screw head or bracket) in the vehicle with the low battery. Keep the clamp away from the battery, moving parts and the fuel system.

Caution: Do not attach the negative cable to the negative terminal of the weak battery! This common mistake could ignite hydrogen gas directly above the battery. Battery explosions can cause serious injury. Even if you’ve got away with it before, use a metallic engine part instead.

5. Now start the car with the good battery, let it charge the weak battery for 5 minutes, then try to start the car with the low battery. If it does not start, turn off both ignitions, make sure the cable clamps are in good contact, and try again. If the car starts with the low battery, wait (about 15 seconds or so) to make sure it does not stop.

6. Disconnect the cables in reverse order: First remove the negative cable from the cracked car, then the negative cable from the car with the good battery. Then remove the positive cable from the car with the good battery (do not touch a grounded part of each car with the clamp of the positive cable). Finally, remove the positive cable from the car with the weak battery. Remember that both motors will be running (with luck!), So be careful when removing cables to avoid straps, fans and other moving parts.

Tip: If you live in a very cold climate, buy the thickest cables you can find (the lower the number, the thicker the cable) to jump-start a car.