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How Long Before Car Battery Dies With Radio On?

The main purpose of a car audio system is to provide in-vehicle entertainment for the driver as well as other passengers. Not only does it lightens the mood, but also helps them in killing time during long-distant routes.

But there are some situations where you need to park the car and sit inside for some time.

Maybe you’ve arrived early for a business meeting. Or maybe your partner is going for some quick grocery shopping while you’re inside the car.

Luckily, you can turn on your car radio even when the engine is off.

But the way you do it is important as you can easily drain the car battery otherwise.

How A Car Battery Works

Before discussing how a car radio affects the battery, we’ll have to understand how a car battery works.

Typical cars come with a 12V Lead-acid battery. When we start the engine, the battery delivers a large amount of current to another car component known as the starter motor.

The starter motor, in turn, starts the combustion engine. Once the engine is on, it rotates the car alternator via the drive belt that rests on an attached pulley. This rotation generates electricity which is then fed back into the battery to recharge it again.

In addition to this, the alternator also powers electrical components of your vehicle such as car audio components, AC, lighting, etc.

The alternator is the one solely responsible for providing power to all these components unless the demand exceeds its capacity. After this, the battery joins in to compensate for the extra load.

And when the engine is off, the alternator stops working and the battery will provide power to your car system until it’s empty.

How Long Before Car Battery Dies With Radio On

If you have a factory car audio system, then it can give you 3-5 hours of music time before draining completely. Some models can give you more time but it depends on many different factors.

The first one of those factors is your car battery age. An older battery will naturally die faster than a new one. You’ll also have to consider weather conditions since the hot climate can cause the water inside the battery to evaporate quickly. This reduces the battery capacity and shortens its lifespan.

So if you live in Florida, for example, your car battery will age faster than a car battery in NYC.

While the factory car radios don’t consume a lot of power, things change if you’ve installed an aftermarket head unit. These aftermarket models come with a lot of extra functionalities such as Apple Carplay/Android Auto, a large touchscreen display, GPS and backup camera, etc.

While all of these features are good to have, they can severely shorten the battery life if you’re using them while the engine is off.

The same goes for 3rd-party subwoofers and amplifiers.

Factory audio systems contain only average-quality basic speakers and a built-in amp. While these components suck at sound experience, they don’t consume a lot of power to operate either.

On the other hand, if you’ve installed a dedicated subwoofer/amplifier combo for deep bass production, it can drain your battery completely in less than an hour.

What to Do if the Car Battery Died While Listening to the Radio?

This is where the main problem lies.

Since the car battery has already died, it won’t be able to deliver the power to the starter motor to start the engine. Therefore, you won’t be able to start your car.

In such a situation, you’re left with only three options: You’ll either need a car battery charger, a portable jump-starter, or a booster/donor car with jumper cables to start your vehicle.

I prefer the jump starter as it’s easier to use than jump cables and works better than battery chargers in time-sensitive situations.

That being said, Lead-acid batteries aren’t supposed to be fully drained like this. It’s OK if it happens a few times but doing this regularly for a prolonged time will make it unusable, eventually.

Modern cars come with safety mechanisms that can stop any electric component if it’s draining the battery while the engine is off.

What if the Radio Stops Working After Recharging the Car Battery?

Oftentimes, car owners have reported their radios to not work after they recharged the battery. It is mainly due to the anti-theft security feature and incorrect jump start procedure.

Many head units come with an anti-theft feature these days that asks for a code (which can be found in the owner manual) every time you disconnect the battery. All you need to do is enter that code and hopefully, the head unit will start working again.

As far as jump-starting is concerned, it is a complex procedure that requires many precautionary measures on your end. If you’re not comfortable with DIYing such stuff, there is a good chance that you’ll make some mistakes that will damage your car components, including the radio.

How to Keep Radio on When Car is Off?

Below are some tips you can follow to prolong car battery timing when listening to music.

Turn Off Other Accessories

Since our battery is limited, we’ll have to save it as much as possible. Therefore, you should turn off other power-consuming accessories in your vehicle, such as headlights, interior lights, windshield wipers, fans, etc.

I would also suggest you to turn off the AC if the weather is not too hot.

Keep the Volume Level Down

More volume level means more load on the amplifier to provide powerful audio signals. It causes the amplifier to draw more current from the battery than usual, resulting in the faster battery draining.

This is why you should avoid cranking the volume knob up to level 11.

Turn off the Subwoofer

Subwoofers are speakers dedicated to low-end frequencies. While the subs certainly help in adding bass and clarity in your sound, their power consumption is way higher than regular speakers.

Therefore, you should turn it off completely when playing music without turning on the engine.

Adjust Head Unit Settings

Factory head units come with only 5-15W RMS per channel. But this can get greatly increased if you’ve installed a 3rd-party head unit. In addition to this, supporting features like GPS, WiFi, and Bluetooth, they consume much more power. I would suggest turning off all these features.

Michael Brown is the founder of, a website that provides car audio installation guides and tips. A self-taught car audio enthusiast, Michael has been installing and modifying car stereo systems for over 15 years.

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