What Can Drain a Car Battery When it’s Off? [7 Reasons]

What Can Drain a Car Battery When it’s Off? [7 Reasons]

Annoying when the car does not start due to an empty battery. 3 possible reasons why it could be. The best electronics Features don’t use anything when the battery is low. Often you notice it already, that the central locking does not lock at all or only hesitantly. At the latest, if nothing happens when the ignition switch is turned, it is clear that the battery no longer supplies power. What can drain a car battery when it’s off? The answer to this question can be explained in 7 points. Do you know the condition of your vehicle’s battery? For a majority of motorists, the battery goes unnoticed unless the engine refuses to start, which happens more often during cold, rainy winter seasons. Extreme temperatures, irregular use, short trips and the age of the vehicle influence the starting power of a battery.

What Can Drain a Car Battery When it’s Off?

It explains the seven main reasons why batteries are discharged even these are switched off and how drivers can protect themselves against this problem.


High temperatures can drain your car’s battery. Unfortunately, this problem is often undetectable before it is too late. To protect yourself, you can apply the following principles: avoid parking your car in the sun as soon as possible and have your battery regularly tested in a qualified technical service center to avoid start-up problems. If your battery needs to be replaced, special expertise and tools are required due to its inter-connectivity with other electrical components in your car. If the electrical circuit between the battery and the computer system of your vehicle is broken, the data contained in the control units and infotainment systems could be lost. Electronic components such as radios and windows may need to be reprogrammed.

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Many motorists believe that when a vehicle is turned off, no battery energy is used. That’s not true. Some systems, such as alarms and clocks, as well as keyless start and navigation functions, need electricity even when your car is parked. This contributes to the drain of your vehicle’s battery. If it remains unused in your garage for several weeks, your vehicle may not start. This is more common in cold weather or if you have an old battery. Drive your car once a week for at least ten minutes can help you avoid starting problems.

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Driving short distances does not allow your battery to fully recharge. In winter, elements that require a lot of electricity such as back windows and heated seats also help to drain your battery. Once a month, make sure you travel a long distance to recharge your battery through the alternator.

Read More About: How a Car Battery Works


As your car ages, the power of your battery may decrease due to corrosion and sulfation, which may adversely affect its load appropriate. Have your battery tested regularly


7 Reasons of Drain car battery

While the car has stood and turned off, a number of components have constantly sucked electricity from the battery. Obviously, the Burning of various lights and headlight turns on, open doors or broken lock. Alarm systems are designed to consume power while the car is stationary. But also car radios can often continue to run, they also consume power when the volume is zero.

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More sensitive are leakage currents and loads in the entire on-board power supply, which consume small amounts of power unnoticed over a long period of time and thus empty the battery over time. This happens especially in older cars when insulations become porous.


The current that the battery stores in between, comes from the alternator. It either runs continuously with the engine or is engaged (for modern cars) according to demand and energy-optimized, for example in sliding mode. If the alternator no longer supplies power, the charging warning light will light up in the Cockpit. In a gasoline engine, it is then only a matter of time, until the spark plugs get no more electricity.

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At the latest since the Smartphone Boom, we know: batteries are wearing parts. Nevertheless, a car battery works chemically different from a mobile phone battery, even it has a point where the components are consumed and no longer provide full capacity. If you regularly take care of the battery, for example by checking and correcting the water level, you can extend its life.

I have mentioned 7 reasons for car battery discharging while the car has been switched off. You can also contribute by doing comment in the comment section.

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