Does ACC drain the car’s battery?

Unlike old models, most modern cars are designed with several labels instructing you what to do to operate the vehicle. For example, an Engine Start/Stop button helps you start the engine and stop it. But the same start/stop button has another use besides starting or stopping the engine, activating ‘Accessory Mode.’ or ACC for short

What is ACC?

Accessory Mode or ACC involves operating the car’s electrical accessories like navigation, audio system, and power windows without starting the engine. The confusion can come on knowing when you are starting the engine or activating the Accessory Mode. Different models of vehicles have unique ways to operate the ACC Mode. 

How to activate ACC?

Are you wondering how to put the car in accessory mode? Here is the way: press the stop or start button without braking, press the stop or start button three times, and press the radio volume knob once. Therefore, the activation of the ACC should not be confused with that of operating the engine because you need to start and stop it.

If you have an older car model, the ACC mode can be activated by rotating the key in the first or second position in the ignition

So, does ACC drain the car battery?

But all with such functions of the ACC Mode, does it drain the car’s battery? Here there are two possible answers, ‘yes, and ‘no’; the ACC won’t drain the car battery. Are you wondering how these two probabilities can occur in your car battery? Continue reading much regarding the ACC system and how or may affect your car’s health.

Let’s slightly start with what happens in your car when you start the engine. You may set your vehicle to have four faces of ignition, where face 1 is when the car is turned off by the key and activating ACC Mode. After all that, there is an engagement stage followed by cranking of the engine; all this occurs in the final position.

But in the second position turning the key or ACC activates the other car’s electrical components. The most activated electrical components may include power seats, lighter, stereo, and cigarettes, although it depends on the nature and type of the car.

Turning on the ACC in your car can activate most high power consumption electrical components such as headlights, ventilators, and defrosters and may drain the battery. In other words, this clarifies the phrase ‘yes,’ the ACC can drain the car battery. On the other hand, the ACC Mode may not drain the battery if no active high-electrical consumption component is linked with the ACC system. 

There is another factor that can affect or determine the ACC Mode draining up the car’s battery which includes the age of the battery. Old car batteries don’t withstand much of the power consumption by the ACC system and associated electrical components.

These batteries can drain even when the car is not in use while the ACC is on. Having a new engine as well can affect the usage of the car battery by the ACC Mode. The ACC Mode and other electrical components can use the battery for more than two hours in a new engine with all accessories working well.

If your car is using old batteries, consider not to leave the ACC active as it will drain the battery completely. As well, consider turning on your vehicle consistently, leaving it for some minutes for your battery to recharge. This will make it easy to restart your engine when you are back to run the car.

How Long Is It Safe To Play Radio In ACC?

Of course, many always like listening to their car’s radio whenever they are chilling somewhere, maybe after driving for long hours or at the parking. But the big worry comes, how long you should play the radio, especially where the car is in ACC.

First of all, several factors are surrounding this situation, such as the condition of the battery and the kind of entertainment system installed. If the battery is in good health, at most, you will run the radio for 2 hours. After 2 hours, you will have to start the engine to recharge the battery.

Also, there is a possibility that you have installed another radio that has more features and a display. Here you should be very careful because a new radio installed is often a cause of a drained battery if it’s not properly installed.

Will Acc Kill the Battery?

Although the ACC drains the car battery in some instances, it won’t kill the battery. The ACC is designed to use little power, which doesn’t bring effect to the battery. What affects the car battery is switching several electrical components that are associated with the ACC-associated appliances.

You have to know that once you turn on ACC, some of the electrical components that consume power are activated, and if you forget and run them for long hours, your car’s battery drains. Therefore, you need to start the engine for a recharge.

Is It Bad To Leave My Car In Accessory Mode?

It is not wrong or bad to leave your car in accessory mode as it has potential benefits such as preserving fuel. Just think of a scenario where you need to light the headlight or listen to the radio, and you will only depend on your car’s engine running; of course, the vehicle will consume a lot of fuel.

But leaving your car in accessory mode can only apply if your battery is in good condition; if it is not in good condition, avoid leaving your car in accessory mode.

How Do I Preserve Battery Life When A Car Is In ACC Mode

  • Always before turning off your car’s engine, ensure it runs for the required period.
  • Replace your battery if it is old
  • Consider disconnecting sub-woofers and amplifiers when listening to the radio.
  • Consider turning the engine after 35 minutes for the battery recharging.


ACC or accessory mode doesn’t use up or drain your car’s battery charged, although its activation can lead to other electrical accessories turning on. These other electrical components may consist of those that consume much power; therefore, they may drain the battery.

Operating the engine should not be confused by operating ACC, although the reading ‘Engine Start/Stop’ or CLOSED can confuse which to activate. When you want to activate or close the Accessory Mode, press the stop or start button without braking, press the stop or start button three times and press the radio volume knob once.

But know that leaving your car in accessory mode is not bad; therefore, you can consider it if you want to use other accessories such as a radio and a charging phone. Always follow some precautions to keep the batteries healthy, as mentioned above in the article.

Scroll to Top