Do Car Audio Systems Drain Batteries? Stereo, Amps, Speakers


When you find that your car’s battery is draining and dying on you often, looking for a cause to the problem is the best thing to do. After finding a cause, you can start to look for solutions and answers to fix the problem with your battery.

Do car audio systems drain batteries? Car audio systems draw power from the car battery and will drain the battery if the engine and alternator are off or if the alternator cannot charge at a rate faster than what the audio system requires. Aftermarket systems may draw too much power, and poor installation may cause parasitic draw.

In this article, we’ll discuss how audio systems drain car batteries and how to keep batteries charged and healthy while still enjoying the audio/sound system.

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• Top 11 Best Car Audio Amplifier Brands In The World


How Car Audio Systems Should Work

Car audio systems are powered by the electrical energy stored in the battery. When the car is on, and the engine is running, the alternator continually charges the battery to maintain a full charge to run the car’s electrical components, including the audio system.

There are cases where the audio system (particularly the amplifiers) will be too power-hungry for the battery and alternator to keep up with. We’ll discuss this situation shortly.

When the car is turned off, and the engine isn’t running, any electrical components still running will drain the battery since the alternator is no longer charging it.

So then, the car’s audio system will certainly drain the car’s battery when left on while the engine and alternator are turned off.

There are three main components to a car audio system: the stereo, the amplifiers and the speakers.

The speakers are passive, meaning they do not require power. Rather, they are powered by amplifiers.

The amplifiers require the most power and are generally incorporated into the stereo/receiver. Aftermarket amps and subwoofer amplifiers are often standalone devices.

The actual touchscreens, radios, and control panels for the car audio system do require power, though it’s very small compared to the requirements of the amplifiers.


Audio System Power Requirements Vs. Battery & Alternator Supply Specifications

It could be the case that an aftermarket audio system is too powerful for the vehicle in question. In this case, the power requirements of the audio system (most notably the subwoofer amplifier/s) demand more energy from the factory battery at a faster rate than the factory alternator is capable of recharging.

A standard car battery will be labelled as 12 volts but will generally be able to provide 12.6 or more when fully charged and nearly 15 volts when the engine is running, and the alternator is charging.

To keep numbers easy, we can say that a 1,200 watts RMS audio system (most of the power is required by the amplifiers) will require 100 amps of current. Power (watts) is equal to the product of current (amps) and voltage (volts).

Note that we’re taking 12 volts in this calculation, which will actually give us higher current estimates.

Now, this is assuming the amp is 100% efficient, which is rarely the case. Class D amplifiers are becoming more popular as large car amplifiers, which have a theoretical limit of 100% capacity, so let’s stick with this for our example. Lower efficiencies will draw more current.

In this example, the alternator would need to deliver 100 amps of current output to maintain a full charge on the battery while the audio system is running.

When the car is turned off, and the audio system is running off the battery, we must consider the battery’s amp hour specification. This is the rating that tells us how much amperage a battery can provide for exactly one hour.

48 amp hours is a common battery specification for car batteries. With this battery, the 1,200-watt (100-amp) audio system will completely drain the battery (from full) in just under 29 minutes.

Of course, we’re discussing a pretty powerful aftermarket audio system here. Most stock audio systems (without subwoofers) will only draw roughly 5-10 amps (60-120 watts). These systems are designed to sound good without demanding too much from the battery. 48 amp hours would run a 5-amp audio system for 9.6 hours before it would be fully drained.

With that all being said, it’s recommended not to drop below a 75% charge in the battery. This will ensure the car will start reliably and maintain good battery health by avoiding sulfation (a buildup of lead sulfate crystals on discharged portions of the battery plates).

So then, we should cut the aforementioned times to a quarter, leaving us with 7.25 minutes and 2.4 hours, respectively.


Atypical Audio System Battery Draining: How Does Parasitic Draw Work?

If your car battery is drained and dies overnight, the issue may be parasitic draw. Parasitic draw means that electronics in the car still use battery power even though the car is off. So, how does that work with the car radio, stereo, amp, and speaker?

New car stereos are relatively easy to install. It takes time, but you can install the car radio or stereo by yourself if you understand the instructions.

However, if the wires are not connected the right way, or someone else installed the radio wrong, it can take power from the battery and cause it to die unexpectedly.

If a car battery is dying after a new stereo install, it should be inspected by a qualified professional.


How To Know If Your Audio System Is Draining Your Battery

Having a car battery that frequently dies without any noticeable cause is annoying to deal with. If you suspect that your car battery is dying because of your audio system, there are some things that you should look out for to see if it is affecting your car.

The first sign to look out for to know if the car’s audio system is draining the battery is to see if the battery is frequently and persistently dying.

Another indication and sign that your car is having its battery drained by your audio system are when the lights inside and outside your car are not at full brightness. Dim headlights and dashboard lights are signs that the battery life is being drained.

The last sign that your car battery is dying due to the audio system is that some of the electronics remain on when the car engine is turned off.

If the stereo and amp(s) stay on while the car is off, the car audio system is draining the power from the battery. If that is the case, call a local mechanic and let them know that when your car is off, the radio or stereo is still on and taking power from the battery.


How To Fix Parasitic Draw

Depending on the source of the problem, there is an easy way to fix the car audio system to stop draining the battery. The first solution is to pull out the radio and follow the instructions to see if the wires are all connected properly after the radio is installed.

Use the instructions and follow the steps to determine if each of the steps was followed and if everything is correct. If you find something that was not done or not done right, follow the instructions and fix the wires and other issues you find. Re-install the stereo and see if the problem with the battery continues.

If that does not fix the problem, make an appointment with your mechanic to help diagnose the problem. They should be able to take your car in and look at it. Then, they can let you know what the issue is, what they have to do to fix it, and what it will cost you for them to fix it.

If the cause for your battery dying is not the audio system, then it is probably a battery issue or something in the engine that needs to be fixed. Talk to your mechanic and see what could be draining your battery other than the audio system. They will be able to tell you what the problem is and be able to fix it.


This article has been approved in accordance with the My New Microphone Editorial Policy.

Arthur

Arthur is the owner of Fox Media Tech and author of My New Microphone. He's an audio engineer by trade and works on contract in his home country of Canada. When not blogging on MNM, he's likely hiking outdoors and blogging at Hikers' Movement (hikersmovement.com) or composing music for media. Check out his Pond5 and AudioJungle accounts.

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