How to Jump-Start a Car with a Dead Battery

Starting a Car with a Discharged Battery

This guide provides instructions for jump-starting a car with a discharged battery using jumper cables and a donor vehicle.

Important Safety Precautions:

• When working with batteries, always wear safety glasses.
• Batteries emit explosive hydrogen gas during normal operation. Keep sparks or open flames away from the engine compartment.
• Do not attempt to start the engine if you suspect the battery electrolyte is frozen.
• Ensure both batteries have the same voltage (12V) and that the jumper cables have insulated clamps suitable for 12V batteries.
• Do not disconnect the discharged battery from the vehicle's electrical system.
• Do not connect the positive (+) terminal to the negative (-) terminal.
• Ensure the jumper cables do not touch any moving parts in the engine compartment.
• Exercise caution when working near rotating engine components.

Important Warnings:

• Warning: Do not use a 24V jump-start system. This can cause overvoltage and damage the vehicle's electrical system.
• Caution: Do not attempt to start the car by towing or pushing!

Using Jumper Cables

The only recommended method for starting a car with a discharged battery is by connecting jumper cables to a spare battery or another vehicle's battery.

Starting a Car from Another Vehicle's Battery

1. Park the vehicles close enough so the batteries are within reach of the jumper cables, but ensure the vehicles do not touch.
2. Engage the parking brake in both vehicles and ensure the gear selector is in neutral (or Park for automatic transmissions).
3. Turn off the ignition and all electrical equipment in both vehicles.

Procedure for Connecting Jumper Cables:

Observe the following procedure and connect the cables in the specified order:

1. Connect one end of the RED jumper cable to the positive (+) terminal of the donor vehicle's battery or the positive (+) connection point.
2. Connect the other end of the RED jumper cable to the positive (+) terminal of the discharged battery.
3. Connect one end of the BLACK jumper cable to the negative (-) terminal of the donor vehicle's battery or the negative (-) connection point.
4. Connect the other end of the BLACK jumper cable to a suitable grounding point on the vehicle with the discharged battery. This should be a metal part of the engine block or chassis, at least 0.5 meters away from the battery and away from fuel lines and brake lines.

Starting the Engine:

• Ensure the cables are not touching any moving engine parts.
• Start the engine of the vehicle with the donor battery and let it run for a few minutes at idle.
• Start the engine of the vehicle with the discharged battery.
• Once both engines are running normally, let them idle for two minutes.
• Turn off the engine of the donor vehicle.
• Do not turn on any electrical equipment in the vehicle with the discharged battery until the jumper cables are disconnected.

Disconnecting Jumper Cables:

Disconnect the jumper cables in the reverse order of connection:

1. First, disconnect the BLACK cable from the grounding point on the vehicle with the discharged battery.
2. Next, disconnect the BLACK cable from the negative (-) terminal of the donor vehicle's battery.
3. Then, disconnect the RED cable from the positive (+) terminal of the discharged battery.
4. Finally, disconnect the RED cable from the positive (+) terminal of the donor vehicle's battery.

Ensure all connections are secure and that the clamps do not slip off the battery terminals, as this could cause sparking or explosion.