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How to Connect Amp to Car Battery?

If you’re like me, you probably love your car and clean it often, but what about the sound system?

If you’re unhappy with how it sounds, maybe it’s time to install an amplifier and connect it to the battery. But, how to connect an amp to the car battery? Let’s find out.

To connect a car amplifier to the battery, follow the steps below:

#1. Identify the type of battery that you have in your car.

#2. Identify the type of amplifier that you have.

#3. connect the battery’s positive terminal to the amplifier’s positive terminal.

#4. Connect the amplifier’s negative terminal to the ground.

#5. Test the connection to make sure it is secure.

As an Amazon Associate, ImproveCarAudio will receive a small commission from qualifying purchases made through the links in this article.

Tip: Each type of battery has its specific way of being connected to the amplifier.

From my experience, the best batteries that work with car sound systems and do not require maintenance are the AGM Optima batteries (link to Amazon).

In this article, I will detail how to connect an amplifier to the three most common types of batteries: flooded lead-acid, gel cell, and AGM.

Can You Hook an Amp Straight to the Car Battery?

If you connect the amp straight to the battery, you have to add an in-line fuse within 18 inches of the battery.

This is to prevent any fire if the amp shorts out. Also, you need to connect the ground wire of the amp to a clean metal surface on the car body or frame.

However, if you ground the amp directly to the battery, it is also recommended to fuse the ground wire.

The reason for this is the safety in case the ground strap from the battery to the body is disconnected or cut, the amp chassis and ground wire become the new ground path back to the battery.

Which Car Battery Type Should Power the Amplifier?

There are two main types of batteries you’ll find in cars:

  • Lead-acid
  • Lithium-ion
  • AGM

Lead-acid batteries are the most common type, which you’ll find in most cars. These batteries have removable caps, so you can add water to them if needed.

If you have a lead-acid battery, it’s best to mount the amplifier as close to the battery as possible. This will reduce the voltage drop between the battery and the amplifier.

Lithium-ion batteries are becoming more popular in newer cars, but their place is often a secondary car battery assigned specifically for the car audio system. The downside of Lithium batteries is their cost, so they are used for more professional car audio systems.

AGM batteries are newer and becoming more common. These batteries are maintenance-free, meaning you don’t have to add water to them.

Optima Batteries OPT8040-218 D35 YellowTop Dual Purpose Battery

Another advantage over lead-acid batteries is that they can be mounted in any position without leaking.

If you have an AGM battery, you can mount the amplifier anywhere in the car.

Both types of batteries will work with amplifiers, but it’s recommended to use an AGM battery if possible. This is because they’re more efficient and will help your amplifier perform better.

How to Run Power Wire From Battery to Amp?

Now that you know what size power wire you need and which type of battery to use let’s look at how to run the power wire from the battery to the amp.

If you’re running the power wire through the firewall, be sure to use a grommet, so it doesn’t rub against the metal and cause a short.

To connect the wire to the battery, you’ll need to use battery terminals. For the amp side of the connection, you can either use terminal strips or screw them directly into the amp’s power terminals.

Once the power wire is connected to the battery and amp, you’ll need to connect the ground wire. You should connect the ground wire to a grounding point on the car.

An excellent place to connect the ground wire is to a bolt that goes into the car’s chassis. Be sure to sand away any paint, so there’s a good connection between the metal and the wire.

One thing to remember when running a power wire is to keep it away from other cables to avoid sound distortion or unwanted buzzing noises. This includes the RCA cables that connect the amp to the head unit.

If the power wire and RCA cables are run too close together, it can cause interference in the audio signal.

To avoid this, run the power wire on one side of the car and the RCA cables on the other.

100ft - 1/4 inch PET Expandable Braided Sleeving – Black – Alex Tech braided cable sleeve

You can also use a wire loom (link to Amazon) to protect the power wire and keep it away from other wires. Wire loom is available at most auto parts stores.

Do I Need a Fuse Between Amp and Battery?

You should always use a fuse (link to Amazon) between the amp and battery. You should place the fuse as close to the battery as possible.

This will protect the wire from getting too hot and burning up if there’s a short circuit.

The size of the fuse will depend on the size of the power wire and the amp.

Which Wires Types Should Connect a Car Amp With the Battery?

From the metal composition perspective, two types of wire are used most frequently for car audio applications: copper and aluminium.

Copper has a much higher electrical conductivity than aluminium, which means it can carry more current.

However, copper is more expensive and heavier than aluminium, but it conducts electricity better.

For most applications, copper is the better choice. It’s more expensive, but it will give you better performance.

Another parameter to look at in the power wires is the shielding. The two most common types of shielding are braided and spiral.

Both types of shielding work well, but braided is more durable and resists abrasion.

Spiral shielding is more flexible, making it easier to run the wire through tight spaces in car chassis.

Once you’ve chosen the type of wire, you need to decide on the gauge. The gauge is a measure of the thickness of the wire.

The thicker the wire, the less resistance it has and the more current it can carry.

Generally, you should use the thickest wire to fit in your available space.

For most car amplifiers, 10 gauge wire is a good choice. However, if you’re using an amp that draws a lot of current, like an amplifier that powers the subwoofer, you may need to use a 6 or even larger AWG.

What Size Power Wire Do I Need for My Amp?

The size of the power wire you’ll need for your amp will depend on how much power the amplifier is rated for and how far the wire needs to run.

Use this formula to determine what gauge (thickness) of power wire you need for your amplifier:

BOSS Audio Systems KIT2 8 Gauge Amplifier Installation Wiring Kit - A Car Amplifier Wiring Kit Helps You Make Connections and Brings Power To Your Radio, Subwoofers and Speakers

Take the rating of your amplifier in watts and divide it by the voltage of your car battery. This will give you the current draw of your amplifier.

For example: If your amplifier is rated for 1000 watts RMS at 14 volts, then you need to take 1000 watts and divide it by 14 volts which equal 71.4. So, you’ll need a wire that can handle 71.4 amps.

Looking at the American Wire Gauge (AWG) chart at Aic-Controls, you can see that a wire that can handle 71.4 amps is a 4 AWG.

The table below shows standard AWG wire sizes for copper wires (OFC) with the corresponding max amperage they can handle.

All values are shown in the RMS wattage:

AWGMax AmperageMax Amplifier Wattage (RMS)
4/02303220
3/02002800
2/01752450
1/01501960
11301820
21151610
31001400
4851190
655770
840560
1030420
1220280
1415210
1610140

As you can see, the thicker the wire, the more amperage it can handle.

Now that you know how to connect an amp to the car battery and what size power wire you need, let’s look at some other things you should know.

Will Amp Turn On Without Ground?

The amplifier will not turn on without a good ground connection.

The ground wire allows the electrical current to flow back to the battery.

If there’s no ground connection, the amplifier cannot work.

Where Do I Ground My Amp?

The best place to ground your amplifier is on a metal part of the car connected to the battery’s negative (-) terminal via the battery’s ground wire.

A good ground connection is important for two reasons.

#1. It ensures the amplifier has a good path for the electrical current to flow.

#2. It helps reduce noise in the system and makes the amplifier sound better.

Can You Use the Negative Battery Terminal as a Ground?

You can connect the ground wire to the battery’s negative (-) terminal, but it’s not the most often used solution.

The negative terminal is where the car’s electrical current flows back to the battery.

If you connect the ground wire to the negative terminal, you will have the best possible ground connection, which will require the ground wire to be the same length as a power wire.

This may slightly increase the amplifier installation cost.

Conclusion

Connecting a car amplifier straight to the battery is the best way to ensure that the amplifier gets the power it needs.

It’s also the best way to reduce noise in the system.

If you’re installing a new car amplifier, make sure to use the correct size power wire and connect the amplifier to a good ground.

FAQ

Why Am I Not Getting Power to My Amp?

Check all the connections to make sure they are tight and secure.

Also, check the fuse to make sure it’s not blown.

If the fuse is blown, it means that there is too much current flowing through the wire, and in most cases, you’ll need to use a thicker wire.

Can I Connect Multiple Amps to One Battery?

You can connect multiple amplifiers to one battery.

Just make sure that the total current draw of all the amplifiers doesn’t exceed the rating of the wire.

Does the Remote Wire Power the Amp?

The remote wire does not power the amplifier.

The remote wire is used to turn the amplifier on and off, and it should always be connected to the remote turn-on wire of the head unit.