How Long Can a Battery Last on Accessory Mode?

The technology of cars has come a long. Now, you can use features such as the Accessory Mode to utilize your car’s accessories when the engine isn’t running. This function is pretty, but how long does it last? 

If you utilize multiple accessories at a time, the Accessory Mode can quickly drain your car battery. This is why it’s best to limit your use of the Accessory Mode to one or two hours at a time. 

If you were unaware of this feature, now is the perfect time to try it out. But, you must take certain precautions to practice the ACC mode safely and efficiently to prevent draining or damaging your car’s battery. Keep reading to learn how to turn on ACC mode in your car. 

How Long Can a Battery Last on Accessory Mode?

Accessory Mode

The Accessory Mode on your car, also known as the ACC mode, is a function that allows you to utilize the vehicle’s accessory without running the engine. That includes radio, power windows, air conditioner, navigation system, and your car’s USB and power outlets. 

This mode is ideal when the car is parked and the passengers inside still need air conditioning, music, mobile charging, and other benefits. However, prolonged use of the ACC mode can drain your car battery or damage it permanently.

How to Turn On Accessory Mode

Follow these steps to turn on the accessory mode in your car.

  • Put your key into the ignition and turn it clockwise until you reach the marked spot that says “ACC,” “ACC Mode,” or something similar. 
  • If your car has a push-to-start button, remove your foot from the brake while pressing the button. 
  • The radio and other accessories in your car will start working. If they don’t turn on, it means your battery is dead. If they turn on but hear the engine running, your car is not in accessory mode. 

How Long Can You Leave the Car In Accessory Mode?

That depends on how many accessories you’re utilizing, the average battery life of your car, the type of components being powered, and your car battery’s health. However, using the Accessory Mode of your car for too long can drain the battery or weaken the battery’s health. 

That’s why it’s best to use the ACC mode for no longer than two hours. However, if you need the Accessory Mode for longer than two hours, you can recharge the battery now and then by running your engine at bi-hourly intervals. 

Most cars have a limited capacity regarding the ACC mode, so you must remember to check the battery status regularly. Plus, if your car’s battery health is already low, it’s best not to utilize the ACC mode unless it’s an emergency. 

Can Accessory Mode Kill Your Car Battery?

Yes, prolonged use of the Accessory Mode can kill your car battery. Using the Accessory Mode too often can severely affect your car’s battery health or even result in battery failure in the long run.

To prevent this, recharge the car battery every hour or so and try not to use the Accessory Mode for longer than two hours at a time. Otherwise, you’ll have to jump-start your car or even replace the car battery, which can cost anywhere between $45 to $250. 

How Accessory Mode Affects Your Car

The problem with the Accessory Mode in cars is that the alternator and engine aren’t running. As a result, the alternator cannot charge the main battery, which is powering the accessories in your car. 

This is why it’s advised not to use the Accessory Mode for too long, especially not overnight. It can completely kill your car battery, affect its battery health, or damage it in the long run. 

How to Use Battery Accessory Mode Efficiently

Here are a few tips that may help you use the Accessory Mode more efficiently to save your car’s battery and get the most out of its onboard system. 

  1. One of the main ways you can fry your car battery on Accessory Mode is by using powerful, aftermarket subwoofers. That’s because these subwoofers require a lot of power to run, so it’s better to only utilize them when your engine is running. 
  2. You may think there’s no correlation between the power seat controls and your car battery, but that’s not true. These controls derive power from the car battery, so it’s advised not to use them in Accessory Mode as it can kill the battery much faster.
  3. Most of the time, Accessory Mode is used to benefit from the AC or heating system while the car sits idle. However, if you find that the weather is pleasant enough to keep the windows down, refrain from using the AC or heating system. Both of these features can drain the car battery quickly due to the climate control, fans, and other electronics being on.
  4. When your car is sitting idle, it’s mostly unnecessary to utilize the plug-in navigational system, as it can drain the car battery faster. If you want to understand the route before driving, save your car battery by looking up directions on your phone instead. 
  5. You may think rolling your windows up and down impacts your car battery, but it does. So, it’s best not to repeatedly utilize these features in Accessory Mode. 

What to Do When Car Dies In Accessory Mode

The battery may get completely drained if you’ve been using the Accessory Mode in your car for over two hours. In this case, you must fire up the engine for a few moments to charge your battery once again. 

Since the alternator is off during Accessory Mode, there’s no way for the main battery to receive power. However, turning on the engine also turns the alternator on, providing power to the main battery instantly. 

It should take between 30 minutes to an hour to fully charge your main battery from the alternator, depending on the time of day and what electrical components are running during the day. 

However, if the battery is already dead, you may connect it to another car’s battery to get a jump-start. Then, once your engine is running, you can disconnect the other battery and let your car’s alternator charge your main battery. 

How to Jump-Start Your Car

Follow these steps to jump-start your car in case the Accessory Mode drains your car battery completely.

  1. Find a car with a working battery; it may help to call up a friend or family member.
  2. Park the cars nose-to-nose and turn off both engines. 
  3. Open both of the cars’ hoods. 
  4. Connect the + cables of one car to another. Repeat this step with the – cables. 
  5. Start the engine of the second car and let it run for a while. 
  6. Disconnect the negative cables before disconnecting the positive cables. 
  7. Close both of the cars’ hoods. 
  8. Start the engine of the first car and let the alternator charge the main battery.

Another solution is to push start the car; follow these steps to do so:

  1. Push the car to the closest flat surface before turning off the engines and its accessories. 
  2. Put the car in neutral and call up a friend to help you out. 
  3. Jump in the car and turn on the ignition as your friend pushes the car.
  4. If the engine turns on, let the alternator charge your main battery.
  5. If the engine doesn’t turn on, call a tow truck to move your car. 

How to Change Your Car Battery

In some cases, the car battery might be permanently damaged if you’ve been using the Accessory Mode too often and for too long. In this case, you’ll have to replace the car battery; follow these steps to do so:

  1. Park your car in a well-ventilated space. 
  2. Open the hood of your car before disconnecting the negative terminal from your battery. 
  3. Using a wrench will help you loosen the nut and detach the black terminal from the battery post. 
  4. Next, you need to perform the same step to disconnect the red, positive terminal. 
  5. Then, remove the old battery from the car and install the new battery. 
  6. While doing so, keep the positive terminal on top and connect it to the positive post. Keep the negative terminal below and connect it to the negative post. 
  7. Then, reconnect the red and black terminals and tighten each nut with the help of a wrench.
  8. You’ve successfully replaced the car battery; you can now close the hood and try to run the engine again. 


The Accessory Mode in your car is ideal for when you want to sit in your car to enjoy a meal or hang out with your loved ones. Plus, it’s pretty easy to access! However, it’s important to use it efficiently to save your car’s battery. 

At this point, you should have some confidence in using your car’s Accessory Mode now that you know ways to prolong your time with this feature. Remember to fire your engine in hourly intervals to recharge your car battery, as it will save you a lot of trouble in the long run! 

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