Accessory mode operates some accessories on battery power while the engine is turned off.
The benefits of accessory mode include convenience, comfort, and fuel saving.
Meanwhile, the primary drawback of accessory mode is increased battery drain.
You can leave your vehicle in accessory mode for hours, but limit yourself to two hours maximum if you heavily use accessories.
You can extend the endurance of accessory mode by avoiding using power-intensive electronics or starting the engine every two hours to charge the battery.
Waiting in a parking lot is never the most comfortable experience. You might be baking in the heat, freezing in the cold, or using up precious gasoline to avoid either circumstance. If it’s a long-enough wait, your phone may even be out of battery and you’re likely bored out of your wits. Luckily for you, modern cars are equipped with an accessory mode.
Accessory Mode Explained
You might be wondering, “What is accessory mode in a car?” Accessory mode relies on your vehicle’s battery to run certain accessories while the engine is off. This often includes the radio, windshield wipers, and other nonessential electrical components. In general, you should avoid using accessory mode for longer than two hours to avoid battery drain.
The way to activate accessory mode often depends on the make and model of your vehicle. Some will require you to turn the vehicle’s ignition switch to “ACC,” while others need a specific button or lever to be activated. When you activate accessory mode, the vehicle’s electrical system will stay powered until you turn off the ignition switch entirely.
In some vehicles, you have to to turn the vehicle’s ignition switch to “ACC” in order to activate accessory mode.
Benefits and Drawbacks of Accessory Mode
Accessory mode is a very handy setting for your vehicle, but there are also a few drawbacks you should be aware of when using it. We’ll take a look at both the advantages and disadvantages of accessory mode in this next section.
Benefits
The benefits to accessory mode mostly stem from the amount of convenience it provides. The radio or music player can give you a good distraction as you while away the time waiting in a parking lot for whatever reason. In a pinch, you can also charge your phone. Certain vehicles will even let you use the air conditioner (A/C) when accessory mode is on. It’s a great alternative to idling, and can save you some gas because accessory mode relies solely on the battery. It’s also good for when your vehicle needs to be pushed or towed.
Drawbacks
One of the most frequent questions about accessory mode has to do with its main drawback. So does accessory mode drain your battery? Because accessory mode relies solely on the battery to power your vehicle’s electronics, it will drain the battery if you use those electronics. This can lead to you losing both the ability to use accessory mode and the ability to start your vehicle entirely.
A vehicle’s battery can run on its own for a time, but it ultimately needs the alternator to keep running. The alternator is the part of your engine that recharges the vehicle’s battery. If the engine isn’t running, the alternator can’t recharge the battery. If the battery runs out in accessory mode while the engine isn’t running, you’ll need to jump-start the battery to get the vehicle started again.
How Long Can I Leave My Car in Accessory Mode?
Keep in mind that accessory mode itself doesn’t drain the battery outright. If you turn accessory mode on and proceed to not use any of the accessories, then no power will be used and your battery won’t drain. Simply leaving your vehicle in accessory mode won’t have much of an effect on your battery, and you can let it stay in accessory mode for hours without worry.
However, if you are using the accessories, it’s best to limit your use of accessory mode to a couple of hours maximum. This maximum might be affected by your battery’s condition and the kinds of accessories you’re using.
Tips for Extended Accessory Mode Use
If you know you’ll need to use accessory mode for longer periods of time in extreme conditions, you’ll want to avoid using electronics that take up a lot of power. These include seat power controls, climate controls like the A/C or heater, and your GPS. Alternatively, you can also start your vehicle’s engine every two hours or so to keep the battery charged. Keep it running for about thirty minutes to ensure a sufficient charge.
Your car’s accessory mode is a handy feature for those long waits in the parking lot. Just be sure to keep an eye on the time. If it’s a choice between boredom and a dead battery, you know what to pick.
Lisa Conant grew up in Canada around a solid contingency of gear heads and DIY motor enthusiasts. She is an eclectic writer with a varied repertoire in the automotive industry, including research pieces with a focus on daily drivers and recreational vehicles. Lisa has written for Car Bibles and The Drive.
The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.
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