How to jump start a car with jumper cables: complete guide

If your car battery dies, you may need to jump start your car. This process can be done relatively easily, provided you have the right tools. Here is a step-by-step guide on how to jump start a car.

How to jump start a car by yourself

No car is immune to running out of battery power. This situation, where electricity cannot reach the starter motor, prevents us from starting the car’s engine. We suggest that you try to start the car using some of our methods.

One of the most common ways is to jump start the car, which requires the presence of another car, or to use a portable jump starter. Another way is the traditional “push start” by dropping it down a hill or even using a jack and rope.

👌 Basic knowledge about your car battery

Basic knowledge to help you prevent and identify problems with your car’s battery.

✔️ How long does a car battery last?

Car batteries do not have an infinite lifespan. They may last three years or ten years, but they will eventually degrade and fail, usually without the car owner realising it.

✔️ My car won’t start (and it’s cold outside)

A particularly cold night can finish off a battery that’s already worn out, discharging it completely or even rendering it useless. Or you may have left the lights on.

✔️ What is a car battery for?

The car’s battery stores electricity, which allows us to use car accessories when the engine is switched off, such as the car’s lighting or sound system. One of its key functions is that it stores enough electricity to start the car’s engine.

Now that you know the basics about batteries, it’s time to check out the guide that will help you revive your car after a battery discharge. After the guide, you can learn more about causes and solutions.

Safety before jump-starting a vehicle battery with a cable kit

  • Check if there is a strong fuel smell coming from under the hood. If so, bypassing your car’s starter with jumper cables is dangerous, as it can cause a fire.
  • Inspect the engine compartment. The wiring should not be covered with a layer of dirt and there should be no cracks or traces on the battery.
  • Try turning on the headlights, sidelights and ambient lighting. If they turn on normally, this means that the battery is not the problem and bypassing it will not help to start the car. If the aforementioned devices do not turn on or the horn or stereo does not work either, then quite certainly the battery is dead. Occasionally, if the lights emit a dim light, this is a sign of a low battery charge.
  • Check the alternator cables. If you discover that they are cracked, it is likely that the voltage is not reaching the battery terminals properly. In that case, bypassing the car with another battery is pointless, as the battery of the vehicle being bypassed to start will be discharged immediately.
  • If possible, measure the voltage at the battery terminals. If the reading is above 12.6 V, then the battery is in good condition and the malfunction should be looked for in other components and assemblies: in the starter motor, ignition switch, starter solenoid, and so on.

⚠️ How to jump start a car with a dead battery: step-by-step guide

  1. Park the vehicles opposite each other with a distance of 45-50 cm between them so that the length of the cables is sufficient to connect them. Warning: The vehicles should not touch each other under any circumstances.
  2. Switch the gear shift stuck to the park mode for vehicles with automatic transmission, and to the neutral position for vehicles with manual transmission.
  3. Be sure to turn off the engine of the donor vehicle.
  4. Apply the parking brake of both vehicles.
  5. Remove the keys from the ignition locks of the vehicles and open the doors in the car with the dead battery. Otherwise, the car’s anti-theft system may come on during override and lock the doors.
  6. Open the hood of the car. Locate the battery. Its exact location is given in the car’s owner’s manual.

How to attach jumper cables

  1. Examine the battery. Find both terminals. The positive terminal is usually the larger one and marked “POS” or “+” and the negative terminal is marked “NEG” or “-“. The positive terminal is often colored red, and the negative terminal is black. When attaching the jumper cables, it is very important not to mix up the battery terminals. Mixing the poles can, under certain circumstances, cause costly damage to the vehicle’s electronics.
  2. If necessary, clean dirt and oxides from the pole terminals with a cloth or wire brush (you can use WD40).
  3. Look at the set of jumper cables. The kit should contain two cables. One is usually red and the second is black. Note that the cables themselves can be different colors, but the alligator clips on their ends are almost always red and black. This color coding helps avoid mistakes when connecting the cables. Connect the cables in the following order:
    1. One red clamp to the positive terminal of the flat battery;
    2. The second red clamp to the positive pole of the donor vehicle;
    3. One black clamp to the negative terminal of the donor vehicle battery;
    4. The second black clamp to an unpainted metal part of the vehicle with the flat battery (mass point). This may be a nut or bolt on the engine block.
      Never connect the positive poles of both batteries!
  4. Make sure the cables do not touch the moving parts of the engine.
  5. Start the donor vehicle’s engine and run it for 10-20 minutes. Turn off the engine.
  6. Try to start the car’s engine with the dead battery. If you are successful, do not turn off the engine for 10-20 minutes. This time should be enough to charge the battery a little. To fully recharge the battery afterwards, a few kilometers of cross-country driving are necessary.

If you have been able to start the car successfully

If the start was successful, remove the cables in reverse order:

  • The black clamp from the unpainted part of the body.
  • The black clamp from the negative terminal of the donor vehicle.
  • The red clamp from the positive terminal of the donor car.
  • The clamp from the positive terminal of the battery, which was dead.

What do I do if the car does not start?

If the car does not start, repeat the procedure: Start the engine of the donor car and let it run for some time, turn it off and try to start the other car. Warning: do not turn on the starter of the vehicle to be started while the donor vehicle’s engine is running, as this may cause the alternator to fail.

The car still does not start after a few attempts

If you have been unable to start the engine after several attempts, visit a car repair shop: Your battery may be completely discharged and it will be necessary to restore or replace it, or other vehicle systems may be faulty. In particular, the engine cannot be started if the following components are defective:

  • Fuses
  • Starter motor
  • Ignition switch

Once you manage to start the car that has exhausted its battery, it is usually advisable to connect the battery to a charger in the car workshop. In any case, it should be checked by a specialist so that the mishap is not repeated on the next trip.

Check out our visual guide on how to jump start a vehicle battery with pictures.

⭐ Best videos to learn how to jump start a car battery with another car

There are many explanatory videos on Youtube where you can clearly visualize how to start your car with a dead battery in the most efficient and safe way. We have selected some of the best ones.

What causes the car battery to run down: Car battery drains

There are several possible causes for a car battery to die:

  • Failure in the alternator of the car that does not feed the battery correctly.
  • Breakage of an electrical cable resulting in loss of electricity.
  • The battery is very worn or old and no longer capable of conserving energy.
  • Owner inattention (emergency lights on all night, for example).
  • When the outside temperature is very low, the battery takes longer to recharge. Cold weather is not good for battery life. If the battery is worn out, it will perform worse in cold weather.

What should I be aware of with a booster jumper cable for car battery?

Not all jumper cables are the same. Because there can be big differences here. A weak jumper cable is no good.

Make sure that the jumper cable has the ISO 6722 standard.

For this, the jumper material must be flexible so that no cable breaks occur. Not only the cable itself, but also the connection clamps must be insulated with plastic to prevent accidents. Only the contact parts should be made of metal.

Before purchasing a jumper cable, please refer to the operating instructions for your car, you will find the vehicle requirements there.

By the way, jumper cables are not included in the scope of delivery of a vehicle. Since a battery can discharge quickly, it is recommended to purchase a jumper cable or a car battery portable jump starter (does not need a second vehicle to be used, but is more expensive than cables).

Can any vehicle start any other vehicle?

In principle, any car can jump start any other vehicle, even a diesel vehicle can jump start a gasoline engine or vice versa. Because the only thing that matters is the battery voltage and this must be identical for both vehicles.

Never attempt to start a car with the help of another vehicle whose on-board voltage is higher or lower than that of your car. For example, if your vehicle is equipped with a battery operating at a voltage of 12 V, do not attempt to connect it to a vehicle with an installation of either 24 V or 6 V, in order to avoid voltage surges.

Jump starting a gasoline vehicle with a diesel vehicle

It is not advisable to connect vehicles with gasoline engines with others with diesel engines, as their batteries have different cold start amperages, making the process ineffective or risking damage to the electronics.

If a gasoline vehicle starts a diesel engine, it must accelerate hard to prevent the gasoline engine battery from discharging undesirably. It is even possible, provided the battery voltage matches, to start a motorcycle with a car. Only a truck should not be started with your conventional car.

Is it harmful to my vehicle if I start another car?

If no mistakes are made during starting and the above step-by-step instructions are followed, no damage will normally occur.

On the other hand, it is not advisable to connect to a vehicle whose battery is not fully charged.

How long should the engine run after lockout?

After connecting the jumper cable, the engine of the car with the battery intact is first started and allowed to run for a few minutes. The engine of the damaged vehicle is then started to close the gap. In order for the car battery to recharge, the engine must run for at least 30 minutes while driving after a successful bridge.

Is it also possible to jump start with a charger?

Yes, it is also possible to jump start with a car battery charger. However, not all chargers have this function. If the charger has a jump start function, bridging works in the same way as with two vehicles.

How long does it take to jump a car?

Starting the car once the jumper cables are connected should take about 5 minutes.

If after those 5 minutes the car does not start, perhaps the problem is that the battery is completely drained. Another possibility is that the cables have been connected incorrectly.

Have you connected the red clamps to the positive terminals? The negative cable must be connected to the battery in good condition and in a metal area of the car with a discharged battery.

If, after rechecking that the jumper cables are correctly connected, the car still won’t start, it’s time to call a tow truck.