Flat battery? Everything you need to know to jump-start your car

HAMBURG: If your car battery is completely flat, the starter motor will only make a dreaded clicking sound - and the engine will not start.

Older batteries in particular are considerably stressed in extremely hot or cold temperatures, and that can become a real problem in cars that are primarily used for short journeys or are rarely used.

In such a situation, you are going to have to jump start your car, but this is unfamiliar territory for many drivers.

"If you prefer to have your car jump-started by a helpful driver instead of calling a breakdown service, the first thing you'll need is jump leads," says Achmed Leser, an expert from the inspection agency organisation Tuev.

It's very important for all those involved in the operation to read the operating instructions for their cars as well as the instructions for use of the jump leads beforehand.

"If you make a mistake, you risk not only damage to the cars but also an electric shock and thus your own health," Leser warns, "and the cables used must always be equipped with plastic-covered pole clamps."

If all the instructions are followed, the jump-starting procedure is quite simple. First, all unnecessary drains on power from the batteries in both cars should be switched off. Only then should the positive terminals of the batteries be connected.

"To do this, first connect the red cable clamp to the positive terminal of the vehicle that is supplying the voltage, then connect the cable to the positive terminal of the flat car battery," says Leser.

The second step is to connect the negative terminals. To do this, the black cable is clamped to the negative pole of the helper's vehicle battery.

The other side of the earth cable is connected to an earth point in the engine compartment of the recipient car, such as a metal part on the engine block. "The negative terminal of the flat battery should not be used, as flammable gases could ignite during starting due to sparks," Leser explains.

The engine of the jump-starting vehicle should not be started until the cable connection between the two vehicles has been established.

You can attempt to start the vehicle with the flat battery after a few minutes of charging. If you're not successful, both vehicles should run for a short time with connected batteries. You may want to turn on some electricity consumers like lights and fans in the receiving vehicle to avoid voltage peaks.

Then the cables can be disconnected in reverse order. First remove the black cable from the earth point and negative terminal, then remove the red cable from the transmitter vehicle, and then from the receiver vehicle.

If the vehicle display shows malfunctions, these must not be ignored under any circumstances - call for expert help, or drive the vehicle directly to the nearest specialist workshop.

"After jump-starting the vehicle, it is essential to drive a longer distance to recharge the flat battery," advises Leser. It is also a good idea to have the capacity and state of the battery checked by a specialist.