How to Install Second Battery for Car Audio System?

Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this...Read more

As we all know a car’s audio system is powered by the battery like other components in a vehicle. Just so you know, you can install a second battery to improve the audio system performance in your car. It’s a good way to improve the music system in your vehicle.

So, how to install second battery for car audio?

To install a secondary battery for the car’s audio, you need to connect the already installed battery to the new one in parallel and then connect the new one to the audio system through the amplifier.

That’s the basics of the process, check out our detailed guide on how to install it, given below.

Installing a Second Battery – What Does It Do?

Batteries are the main power source of a vehicle, which includes the audio system too.

Although it’s true a secondary battery installation isn’t absolutely necessary for your vehicle, then again it does provide many benefits.

The most obvious advantage is much more reserved power, which comes in real handy from time to time.

This extra power from the additional battery not only lessens the load on the primary battery but also helps improve the sound system in your car.

What Do You Need to Know Before Installation?

Before we go ahead and start showing you the process of how to install a secondary battery for car audio, we’d like to share what you’ll need to complete this process.

Here’s what you’ll need:

  1. The battery.
  2. Two fuze boxes.
  3. An Amplifier.
  4. A wrench.
  5. Protective caps (plastic).
  6. Power Wires.
  7. Battery box/Stand.

Additionally, you should also decide which connection type you’re going to use.

There are two types of connection for installing a secondary battery.

  • Series connection.
  • Parallel connection.

Series Connection

In this type of connection, you connect some series of power wires from the primary battery to the secondary battery through the amplifier.

Although this type of connection helps you connect both batteries to the audio system, however, the primary battery resistance will be higher than the secondary battery.

NB. When you choose to go for a series connection, you need to keep one thing in mind it’ll create a higher resistance; and the higher resistance will lead to overheating and will hinder the durability of the primary battery.

Parallel Connections

In this type of connection, the distribution of power and resistance are equally divided, which balances out any distortion between the two batteries equally.

As a result, none of the batteries need to handle extra power or resistance and keeping them safe from any extra draining.

Therefore, we’ll recommend you use the parallel connection type for your car and battery safety.

How To Choose the Secondary Battery for a Car’s Audio System?

Choosing the right secondary battery is equally important as installing it in your car’s audio system.

How To Choose the Secondary Battery for a Car’s Audio System

When you’re choosing an additional battery for your car there are different crucial factors that play a vital role, which you can’t avoid.

If you do, then the installation won’t be successful for long, you’re sure to face hindrances along the way.

So, to avoid that, here are some of the key factors that you should keep in mind:


The Battery’s power varies with different types, manufacturers, and sizes. Selecting a secondary battery is different from selecting a primary battery.

When selecting a primary battery you need to adjust the battery according to the vehicle’s engine, electrical circuits, and required ignition power.

The sole purpose of a secondary battery is to provide the necessary backup power to the primary one.

So, when shopping for a secondary battery you must take the power rating of the primary battery into consideration. Otherwise, the installation process will render useless as it won’t work.


As you know, there are a variety of types of batteries available. Choosing the right type is critical.

It directly affects the way of the installation process, as it determines the way you’ll be installing it to your car’s audio system.

If your existing primary battery is lead acid type, you can’t just choose a lithium-ion battery.

It’ll create a power supply distortion, thus creating a hindrance throughout the entire car’s system.

So make sure you choose the same type of battery before you buy.


Batteries also come in different shapes and sizes, and they do serve a purpose.

From the different shapes and sizes, you have to find the right one that’ll fit in the limited space you have in your car.

Hence, calculate the space you have for the battery and choose accordingly, but remember don’t compromise on its power and type.


The battery’s overall quality is also a factor that you should keep in mind. Its power, size, and type will be rendered useless if it has a downgraded quality.

So, needless to say, you can’t make any compromises when it comes to battery quality.

It’ll not only affect the primary battery but also your car’s overall performance.

How to Install a Second Battery For Car Audio?

How to Install Second Battery for Car Audio

After choosing the right battery with the same power, type, and good size, now it’s time to install it to enhance the car’s audio system.

Here’s the step-by-step guide to installing a second battery for a car audio system:

Step 1: Choose the Right Place

Choosing the right place to install the second battery is the key step of this installation process. You must measure the space you wish to install the battery.

Keep in mind, the second battery needs to be connected to both the primary battery and the amplifier.

Also, make sure the space is close to a ground lead, where you’ll attach the secondary battery’s fuze connection.

Step 2: Attach the Battery

After, you’ve found a proper place to install the battery attach the battery securely by using a box/stand.

Step 3: Disconnect the Primary Battery

Then, disconnect the power wires from the primary battery, both positive and negative terminals.

Otherwise, if you leave it connected, the sudden surge of power can short-circuit both batteries.

Step 4: Connect the Power Wires to The Fuze.

After disconnecting the power wires from the primary battery, now you need to attach the wires with a fuze box.

It’s a gateway from the primary battery to the secondary and the amplifier.

Connect the power wires to the fuze.

Step 5: Connect the Grounds.

After wiring in the fuze box is completed, now it’s time to connect the grounds. If you know where to connect the ground wire car battery it’s a very easy step to complete.

To do that, you need to find the ground cable and attach it to the ground lends in the secondary battery and connect it.

find the ground cable and attach it to the ground lends in the secondary battery and connect it

Step 6: Connect the Batteries

Now that you have connected the ground on both batteries and the amplifier, it is time to connect the second battery to the primary battery through the fuze and amplifier.

Connect the batteries

And that’s it your second battery for the car’s audio system is installed. If you want a more visual approach, you can check out this video tutorial.

Should You Use an Old Battery or Get a New one for a Secondary Battery?

When you use a car for a long time, it’s quite natural to have a few spare batteries lying around in the garage.

If that’s the case, then you might be thinking about whether or not you could use any of those for a secondary battery connection for the audio system.

Well, with all honesty, it completely depends on the old battery’s condition.

If it has enough power to charge and discharge when needed and supports the primary battery well, then why not?

However, if its power outage capacity has dropped below 12.6v then it’s a good idea to avoid using the old battery and get yourself a new one.

So make sure you measure the battery voltage with a multimeter.

On the plus side if you can use the old batteries you can save money on buying a new battery for secondary use for the audio system.

Bottom Lines

Installing a second battery to the car’s audio system is a great way to make the most out of your car’s battery without stressing it out.

As you know by now, it helps keep the battery power reserved and provides improved audio quality.

Make sure you follow our guide on how to install a second for car audio. With this guide can easily install a secondary battery with the primary battery, even if you don’t have any idea how to.

Furthermore, if you do have a spare usable battery lying around the garage, and it’s compatible with the already installed battery then you shouldn’t spend money buying a new one.

Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this site Batteryquery to help people purchase the right battery for their vehicles. The reason behind creating this site is to help my customers purchase the right car battery who often purchase the wrong one due to their lack of knowledge.

More Posts

Leave a Comment