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How To Install A Second Battery For Car Audio – Step By Step

Hooking an extra car battery is a tough challenge, but it can be easier if you know the ABC of it. You might not know what battery to choose or how to wire them. You might be afraid that anything might go wrong, and you might need someone to assure you. Things can worsen if you have never encountered a car’s electrical system. Some of you might even have tried and failed.

But. No worries. No matter what questions you have or what problems you are facing, we have put out 11 steps on how to install a second battery for car audio.

Before jumping to the steps, first you should know about the functionalities of Parallel and Series connections. Because, without the proper knowledge of connections, you might sabotage your vehicle. So, we will start from that.

If you want to maintain the same capacity with increased voltage, then you should go for a series connection for the car batteries. In a series connection, you will connect the positive and the negative ends of two batteries.

The voltage you will get from a series connection is the sum of the individual voltage of the batteries. If you wire two 10V batteries in series, the connection will produce 20V. But, the total capacity will be of a single battery. If you use two 50Ah batteries, you will still get a 50Ah capacity. 

But a series connection literally means firing up your own vehicle. It creates higher resistance, leading to overheating of the system. Also, the whole system will shut down if anything terrible happens to one of the batteries.

That is why car experts advise going for a parallel connection.

A parallel connection increases the capacity while keeping the voltage unchanged. To connect your batteries in parallel, you need to wire the positive terminals of two batteries with each other and do the same for the negative terminals. If one battery fails, the other can produce power at a reduced capacity, and you can have an uninterrupted audio experience.

11 Steps for Installing a Second Battery for Car Audio

Now we will guide you step by step, for you to avoid any mistakes. Even if you are not familiar with the process, you will find zero difficulty following the steps. But you first ensure

Step 1: Preparing the Tools

First, you should gather all the necessary tools to install a second battery for car audio. Once you have everything in hand, you will be able to work without any disruptions. The tools you will require are –

  • Second Battery: You should choose the optimum battery based on size, power rating, and type. For more details to choose the right battery, read out this guide
  • Battery Isolator: The battery isolator prevents the batteries from drainage and keeps them separate. 
  • Battery Tray: It provides a stable base for the battery to rest upon and ensures that the battery is not shaking while the car is running. 
  • Battery Box: A battery box is safer than a battery tray because it protects the battery from harsh environments like moisture and acid leaks. 
  • Battery Holder: These are strips that hold the battery with the tray. 
  • Power Cables: These are exclusively designed heavy-gauged and insulated wires to transmit high electric charge between the battery and the system. 
  • Ground Cables: They are the same as the power cable, but they connect the battery to the car chassis. 
  • Fuse and Inline Fuse Holder: The Fuse protects the battery and the electrical system from short circuits and potential damage. The inline fuse holder secures the fuse in a steady position. 
  • Battery Terminal: It holds and connects the wire with the battery. 
  • Terminal covers: Protects the battery terminal from accidental short circuits. 
  • Dielectric grease: A kind of non-conductive grease that protects battery terminals and connectors from corrosion.

Besides these tools, you should also keep your hand on the adjustable wrench, screwdriver, wire cutter, stripper, crimping tool, and voltage tester.

Step 2: Selecting the Battery Location

When adding an extra battery for the car audio system, you want to make it as close to the amplifier as possible. And so, the car’s trunk will be an optimum place. The location should be away from heat sources.

Step 3: Disconnecting the Primary Battery

To ensure safety, you need to disconnect the primary battery's negative terminal (usually black or marked with a "-") using a wrench before starting anything else.

Also, do not forget to disconnect the link between the alternator and the battery.

Step 4: Mounting the Secondary Battery with the Battery Tray/Box

After screwing the battery tray/box in the selected position, you should attach the secondary battery so it cannot move while running.

Step 5: Installing the Battery Isolator

You need to place the isolator near the main battery.

Then, link the isolator's input side to the positive terminal of the alternator.

Now, you should connect one output of the isolator to the positive terminal of the primary battery and the other output to the positive terminal of the second battery using power cables.

Installing the Battery Isolator

Step 6: Setting up the Inline Fuse

You should use at least two fuses to safeguard your battery and amplifier while hooking a second battery for car audio.

The first fuse will be in between the positive terminals of primary and secondary battery. The second fuse will be between the positive terminal of the secondary battery and the amplifier.

Keep the fuse holder close to the primary battery’s positive terminal and the amplifier’s.

Now, using the crimping tool, you should cut the positive power cables to connect them with the inline fuses.

Setting up the Inline Fuse

Step 7: Connecting in Parallel

You need to connect the primary battery's positive terminal with the auxiliary battery's positive terminal. A fuse would be used in between the connections as per step 6.

Another positive power cable should connect the amplifier with the secondary battery’s positive terminal.

Lastly, make sure to connect the primary battery's negative terminal with the auxiliary battery's negative terminal.

Step 8: Grounding the Second Battery

Using separate cables, you should now connect all the negative terminals with the car chassis for a safer connection.

Grounding the Auxiliary Battery

Step 9: Applying Safety Measures

To prevent corrosion, put dielectric grease in the battery terminals, and to prevent accidental short circuits, you should use terminal covers.

Step 10: Reconnecting the Primary Battery

You may now reconnect the negative terminal of the primary battery to complete the circuit.

Step 11: Testing the Installation

Now, you can check the voltage of both batteries to ensure your batteries are placed right. If the check is all good, you can start your car and enjoy the audio to the fullest.

Anatomy of the both batteries set up

The Outro

When it comes to enhancing power capabilities, upgrading your car’s audio setup is stressful, but it can be a piece of cake with proper guidance. Upgrading your car audio is not just about high performance or longevity. It should also ensure safety while you and your guests enjoy the music.

As we have explored, you now know every decision made in the process determines what the outcome will look like. Our comprehensive guideline ensures you gain enough knowledge to install a second battery for better car audio.

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