Jumpstarting your car 101: There is a right way to do it

Sooner or later, everyone finds themselves in a situation where their car needs a good jumpstart. While MetroMile offers roadside assistance, if you find yourself with friend that doesn’t have this service, or think you can get the job done quicker, you might want to know how to jump your car yourself, and if that’s the case, read on…

First up, you’ll want to make sure that the battery is the problem. If there’s another reason that your car won’t start, then jumping the battery won’t help you. Having dim headlights or a dim dashboard, or no “juice” when you turn the key is a good indication that you left the lights on, or that the battery needs replacing. 

In order to jump a car, you need to have a companion car relatively close to the battery of the dead car. Find out where each battery is located, so that you can get the batteries as close to each other as possible. Some jumper cables are longer than others, so this is especially important if you have short cables. Batteries are usually in the front part of the car, but not always. 

Each battery will have a positive and a negative terminal, usually prominently marked with a + or – sign.

Safety is a big concern with jumping a battery, don’t skip any safety steps!

  • Make sure that the disabled car is turned off, and that the electrical items are turned off, such as the lights, the radio, etc. 
  • The cars should be close to each other, but not touching.
  • Inspect the battery. If it is oozing, or broken, then call a cab instead, or get a ride, and replace the battery entirely.
  • If either battery is corroded, then you can usually remove the corrosion from the battery cables and posts with a stiff brush or coarse cloth. It is very important to have the connection be clean on both batteries.
  • Use gloves if you have them.
  • Protect your eyes, if possible.
  • Concerning the jumper cables, be sure that they don’t touch each other after they are connected to the car, or during the connection process. The arching can be fatal! The cables should be unwound, not left in a bundle, so that you have good control over the clamp ends. 
  • If you don’t have jumper cables in good condition, then consider other options. You should have both a red cable and a black cable. 

The Connection sequence

  1. First, connect a red cable to the positive terminal on the dead battery.
  2. Second, connect the other end of the red cable to the positive terminal of the good battery. 
  3. Third, connect a black cable to the negative post on the good battery. 
  4. The fourth sequence is a really important one, because this will close the circuit. If the black cable is connected to the negative post of the dead battery, then you risk igniting gas that is coming off of the battery. Look for an exposed, unpainted metal surface, such as a battery bolt or other shiny metal attached to the engine. If nothing is apparent then the negative post may be a last resort.

Keep the cables away from the engine so that moving parts don’t damage the jumper cables, and so that the clamps don’t touch each other.

Start the working car first, and let it idle. Rev it a little, but not too much, for about 30 to 60 seconds. This will actually charge the dead battery, even though the dead car is not started yet. 

Now try to start the disabled car. If it doesn’t work, then turn off the engines, disconnect the last-connected cable, and try to secure the connections at all points. Use a longer “charging” attempt this time by running the engine at a high idle for about five minutes. If the disabled car still doesn’t start, then you will probably have to replace the battery.