Starts a completely empty battery

Car battery empty - this is how the jump start works

Signs of a dead battery?

If you have a car with remote unlocking or a keyless entry system (i.e. keyless entry), you may not even get into the car without further ado when the battery is flat. The car's communication systems are practically always on standby and can therefore fail if the battery is flat. If nothing happens when you press the button on the car key, this is often a sign that the battery is empty. But there are many cars, such as large SUVs, station wagons or minibuses, that have two batteries. Here the larger, stronger one is responsible for the starting process, i.e. the power for the starter. In such cars, the smaller battery supplies the electricity for the communication systems mentioned. So you can get into the car without a problem, but then nothing happens because the large battery is empty. Typically, when the battery is flat, the car only makes a click or a tired turning noise from the starter. It gets weaker from trial to trial. The light and other systems no longer work either. These are all signs of a dead battery.

What do you have to pay attention to before starting aid

  • Empty battery vs. marten bite

If nothing can be switched on and the car does not start, the battery is most likely dead. But: If the radio or light can still be switched on normally, it is possible that a marten has bitten you through individual cables. In such a case, do not start or drive the car under any circumstances. If other important assistance systems such as power steering or brake booster fail while driving, it will be life-threatening. A car with a marten bite has to go to the workshop.

Find out in the operating instructions what type of battery (s) are installed in your car. Then it depends on who or how you can provide start-up help. There are special features during the starting process for cars with automatic transmissions, automatic start-stop systems or hybrid drives. If you are not sure, you can ask the workshop or call a breakdown service.

  • How does the on-board electrical system react?

Always read your vehicle's logbook to see whether it is easy to connect and disconnect the battery. Cars with a lot of electronics on board in particular can react sensitively to such a thing. You have to adjust some vehicles first to reconnect a battery. Experts speak of learning the battery. The more expensive the car, the more complicated it usually becomes.

Jump start with the car

To get back on the road at short notice, you can get help from another car. Both cars must first be off. Then the positive poles of the batteries are first connected with the red jumper cable. Then you connect the black cable to the negative pole of the full battery, but do not connect the other end to the negative pole of the empty battery. Instead, you attach it to an unpainted, immovable metal part on the engine block of the recipient vehicle. Many, especially new, cars optionally have special, marked ground points to which the other end of the black cable can be attached. You can find out where they are in the operating instructions. Only when everything is connected do you start the electricity supply vehicle, wait a while and then start the electricity receiving vehicle. If this does not succeed after up to ten attempts, you do not have a pure charging problem and should get help from professionals. When your car starts, you switch on a few consumers such as the radio and ventilation on the recipient vehicle. This protects the on-board electronics. Now let the recipient vehicle continue to run, first disconnect the black negative cable and then the red positive cable.

When buying charging cables, please ensure that the charging cable has a sufficiently large cross-section. Cars with petrol engines need a cross-section of at least 16 square millimeters, with diesel vehicles it is even 25 mm². Your charging cable should be marked with the DIN standard 72553.

Jump start with the power booster

Similar to smartphones, there are also so-called battery packs or start-up boosters for car batteries. They cost from 50 euros and are clamped directly to the connected battery. Then you can start the vehicle. Important: the battery pack itself should be charged to at least 25 percent and not have been left in a cold car overnight. So always take these devices with you in the warm. A cold battery pack has no chance at minus 18 degrees. A charger with a boost function can also help. If, on the other hand, you only have a normal charger, it should hang on the battery to be charged for at least one to two hours before the car can start again.

Pushing only works with a few cars

The energy requirements of the fuel pump, starter and other devices in modern vehicles are so great that normal pushing is not enough. If you try anyway, there is a risk that the catalytic converter will break. With diesel cars, you will almost certainly need a distance of several hundred meters before it can work. You should only try to push it if you have no other option, but only at most one. It doesn't work with automatic vehicles anyway.

Beware of traffic

Whichever way you get your car going again, always pay attention to the traffic. Secure your location with a warning triangle. Wear a safety vest yourself. If in doubt, seek help from a professional.

Charge the battery as a precaution

If you don't get the necessary charging time on your way to work, you can occasionally help your battery with a trickle charge using a charger. You don't have to remove the battery from the car to do this. However, it is important to switch off the ignition and disconnect the connections for the plus and minus poles from the battery. In principle, a car battery should not be connected to the car's electrical circuit while it is being charged by a charger. Some devices sometimes emit a stronger current than the on-board electronics can handle. So only leave the battery connected if the description of the charger expressly allows it. The battery is fully charged again overnight. Trickle chargers are available from 15 euros, better devices with a charging timer and overcharge protection cost from 30 euros.