How to connect the battery cables

Here we are, the battery of your car is flat : whether it has happened for having forgotten the lights on with the engine off, for excessive cold, or for inactivity, the procedure for groped charging is the same, and requires special cables. Let’s find out how to use them correctly.

To learn more, read what to do when the car does not start .

Low car battery and ignition cables

Whatever the cause that has discharged the car battery, you will have to try to restart it using the ignition cables : the operation is easy, but a few small tricks are needed to maintain maximum safety.

You will need:

  • jump leads– long enough to connect to another vehicle
    • a car with a working battery – check that they are of the same voltage (normally 12V)

How to connect the cables to the battery

Here’s how you should proceed when you have a car that “lends” you energy, after checking that no battery has any damage (leaks or ruptures):

  • position the cars with the engine compartments as close as possible
  • turn off the car and open the engine compartments of both
  • turn off anything that absorbs voltage, such as radios, lights, windshield wipers, disconnecting any devices being charged
  • take the cables in your hand, without crossing them

At this point you have to connect them in this order:

  1. the first red clamp to the positive pole (+) of the flat battery
  2. the second red clamp to the positive pole (+) of the charged battery
  3. the first black clamp to the negative (-) pole of the charged battery
  4. the second black clamp to the negative pole or to a piece of metal of the body (not rusted and not painted), possibly away from the battery

Now you just have to start the rescue vehicle, letting the engine run at idle for about 5 minutes: only now can you try to start your car, and repeating the procedure if it doesn’t work.

When the vehicle with the battery on the ground remains on, you will have to let it recharge for at least another 5 minutes, ending the operation by disconnecting the cables in the reverse order to that of connection.

At this point it is always better not to turn off the car for at least 20 minutes, and to use it (when possible) with all devices that absorb current off (lights, headlight washers, etc.).

The tricks of the trade

For every problem there is a solution, and this maxim is also valid in the world of mechanics.

Remember not to put your face near the battery (it is better to wear eye protection); flat batteries can produce hydrogen gas (highly flammable), so always connect the positive pole of the flat battery first, avoiding sparks. Finally, always use thick and quality cables (25 mm section).

A note: the battery amperage of diesel cars is usually higher than that of petrol ones, so always check this.


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