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How to Jump-Start a Car With a Bad Alternator

by Pamela Gardapee

A bad alternator can prevent a car from starting because it did not charge the battery when the car was running. However, even if you have a dead battery because of the alternator, you can still jump-start the car using the following method.

Step 1

Use another car with a good battery to jump-start your car. Make sure that the car is turned off.

Step 2

Connect the positive (red) cable to the positive terminal on the car with the bad alternator. Connect the red cable on the opposite end of the jumper cables to the positive terminal on the car with the good battery.

Step 3

Connect the negative cable (black) to the negative terminal on the car with the good battery. Connect the other end of the black cable to a place on the engine as a ground. This can be anywhere on the engine block that is clean and not painted or chromed. Never place the negative cable of the car to be jump-started on the battery.

Step 4

Start the car with the good battery and allow it to run about three to four minutes. Try to start the car with the bad alternator; if you need more charging, allow more time.

Step 5

Remove the black cable from the engine block. Remove the red cable from the positive terminal on the car with the alternator problem. Keep the cables away from each other while removing the black cable from the jumper car, and remove the red terminal.

Drive the car straight to a mechanic. A bad alternator will mean that you are not going to have lights unless the battery has a full charge to last a little while.


  • Use a cardboard box to clip the cables to as you apply them, and remove them if you cannot keep the cables separated yourself.


  • Never do this at night, since your lights probably will not work for long, if at all.

Items you will need

  • Jumper cables
  • Car with a good battery

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