Car battery empty? How to avoid a breakdown

The number one cause of breakdowns is the car battery. What can you do if it's empty? How to avoid the engine no longer starting? And how do you recognize in advance that the battery is weak? Tips and tricks from the experts.

• First sign: A powerless engine at the start

• First aid: Jump start – always in the right order

• Electrical consumers strain the battery

Cause of breakdown number one: Empty battery

It's not the engine, not the vehicle electronics and not the fallen exhaust: In most of all car breakdowns (around 42 percent), the starter battery failed. Since it is subject to wear and ageing, every driver has to struggle with a weakening 12-volt battery over time.

The problem does not only affect old vehicles: Depending on the conditions of use and use, but also in the event of faults in the electrical system (e.g. corrosion of electrical connections or possible silent consumers), a batterycan be so badly damaged after just a few months that it is necessary to replace it. Then it is important to buy the right car battery.

Basically, the lower the temperature, the worse the performance. This means that the probability of a battery breakdown is significantly increased, especially in the first cold days before winter and at significantly sub-zero temperatures.

First aid: The right jump start

If the car does not start, a jump start using a jumper cable can help. In principle, each car can give a jump start to another vehicle. However, it is essential to follow the correct sequence of the necessary steps. You can find step-by-step instructions here.

Attention: After several unsuccessful attempts to start the start, damage may occur. At the latest after the starter aid has failed a third time, it is better to get professional help.

How do you charge a dead car battery?

An empty battery can be charged with a suitable charger at a household socket. Small chargers that can be connected overnight are often sufficient for this.

If you cannot connect the battery externally, then drive for a long time on routes that are as free as possible to recharge the car battery.

Signs of a low car battery

If the engine only starts powerlessly (i.e. the starter turns more slowly and "stalls" when starting) and the interior lighting flickers, then these are the first signs of an aged battery.

An alarm signal for cars with an automatic start-stop system is that it does not switch off the engine – even if all the necessary conditions are met. So although the engine should stop automatically at traffic lights, for example, it continues to run. The reason for this may be that the vehicle electronics have detected a weak battery and therefore do not put additional strain on it due to constant starting processes.

How to check the battery and charge level

Since a conventional starter battery for combustion engines is primarily stressed by starting, it must above all deliver high cold-start currents. This is exactly where an aged battery fails, which explains the frequency of breakdowns in the first cold days of the year. Our tip: As soon as the first indications of a defect (see above) or if the last battery replacement was more than three years ago, have the battery checked before next autumn.

Care: How to make your car battery last longer

A breakdown can be avoided. Good care, for example, extends the life of the battery. And if you recognize early on that it is going to give up, you can take countermeasures before the total failure. Here are the tips from the ADAC:

• Avoid heat build-up! What many people don't know is that the battery ages quickly at very high temperatures. If your starter battery has an insulating jacket, it should be replaced after damage. And: If possible, don't leave your car in the blazing sun for days on hot summer days.

• Reduce consumers: Many electrical consumers can cause the battery to be deeply discharged. Then the lifespan suffers. Therefore, when the engine is switched off, always make sure never to operate the radio, lights and ventilation for a long time without the engine (with "ignition on"). While driving, use electrical consumers (e.g. rear, windscreen heating, seat heating) only for as long as necessary. Incidentally, this also applies to electric cars, which also have a 12 V starter battery on board. However, it is clear that safety-relevant consumers such as lighting should not be skimped on in poor visibility conditions!

• Use the charger: In the case of purely short-distance vehicles or longer periods of idleness, the generator in the vehicle cannot recharge the battery (enough). With a charger, deep discharge can be avoided. Larger, but also more expensive devices are often equipped with a jump start function.

• Avoid operating errors: It is well known that negligence such as leaving the lights on (including the interior lighting!) drains the battery. But not that unlocked doors in the parked vehicle can cause the car to "draw electricity". The reason: Some control units then stay "awake" for a while or do not "go to sleep" at all (see also ADAC test quiescent current). So always close doors and tailgate correctly and lock the car.

• Keep the battery clean: The contact between the battery terminal and the battery terminal terminal should be free of dirt and sit firmly. If necessary, check that the battery terminal terminal is stuck. Use the protection prescribed by the vehicle manufacturer (spray or pole grease) to protect the connections from corrosion.

• For vehicles parked for a longer period of time, the following applies: In older vehicles, it is advisable to remove the negative terminal from the battery. Because: for safety reasons, it is always advisable to disconnect the negative pole (ground connection). This prevents the positive terminal on the battery, for example, from accidentally being connected to the vehicle ground via contact (slipped tool) and thus triggering a short circuit.

• In modern vehicles with on-board computers and teach-in electronics, disconnecting the starter battery can lead to problems. Here, the ADAC recommends – if possible – connecting the starter battery to an external battery charger about once or twice a quarter. Alternatively, permanently connect to a battery charger with trickle charging function

Battery check at the ADAC Regional Club

The voltage at rest can be checked with a simple voltmeter available to everyone. The measurement provides at least a first indication of the state of charge:

However, such a measurement does not record the complete "state of health" of the battery. This can only be done by a professional battery tester who is able to simulate the load on the battery, monitor the starting process and determine the cold current power for the correct diagnosis of the battery.

This professional battery test is carried out by a car workshop or by the ADAC. You can have the battery tested at theADAC testing services of the regional clubs. The diagnosis and working time for the battery check are often free of charge for ADAC members (there may be differences depending on the regional club).

Battery breakdown: The Yellow Angels help

And if the battery does run out: The Yellow Angels of the ADAC road patrol help quickly and easily. The trained specialists provide troubleshooting, provide jump start assistance or, at the request of the member, replace the battery on the spot with a new one if the old one can no longer be saved.

Expert advice: Matthias Zimmermann, ADAC Technical Center Landsberg