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How to Wire Car Stereo to Battery?

When wiring a car radio to the battery, there are two main options: direct wire or through the harness.

If your radio and car have a harness, you only need to connect the radio’s harness to the harness coming out of the dashboard, but how to connect the car radio to the battery when you do not have a harness? Let’s find out.

To connect the car radio with the car battery, you need to take a red and yellow wire and connect them together to the battery’s positive terminal. Next, take the black wire and connect it to the negative terminal.

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Tip: When connecting the radio directly to the battery by bypassing the ignition switch, the radio will run even if you turn the engine off.

To avoid this, you must connect the radio’s red wire to the accessory wire in the dashboard. This way, the radio will work only when the key is in the accessory position.

In this article, I detail connecting a car radio wire to the battery and some tips on ensuring it is done correctly and safely.

Can I Connect Car Stereo to Any Battery?

You can connect the car radio to any type of car battery, however, it has to be a 12V battery. This is because the car radios, at least for passenger cars, require 12V to operate.

When it comes to the battery type you may use in the car, it can be either a lead-acid battery, AGM or lithium-ion battery.

Do I Need an Extra Fuse for Car Stereo?

If you wire the car stereo directly to the battery, you may need an extra fuse near the battery.

The reason is that if there is a short circuit in the car radio wiring, the extra fuse will prevent any damage to the wire by blowing off itself. The fuse should be of the same size as your main radio fuse.

If you are unsure about the fuse’s amperage, check your car radio manual or the wiring diagram for your specific car model.

When it comes to fuses, there are two types: blade and cartridge. I prefer using the cartridge type as they are more reliable, but the choice is up to you.

Most car radios have one fuse, but some models have two. In this case, you need to use the central fuse, which will be a summary of both radio fuses.

For example, if your radio has two 10 amp fuses, you should add one 20 amp.

How to Wire Car Stereo to Battery (Step-By-Step)

#1. Start by disconnecting the negative terminal of the battery. This step is crucial as you do not want any power going to the radio while working on it.

#2. Once the negative terminal is disconnected, start with preparing the power wires. The wire must have enough length to reach the battery.

#3. The next step is to connect the red and yellow wires and run them to the battery’s positive terminal. Make sure you use a wire that is thick enough so it can handle the current. I suggest using at least 16 gauge wire (link to Amazon).

KnuKonceptz Kolossus Flex Kable 4 Gauge Power Wire Black OFC (Sold in 5 Foot increments)

#4. Now take the black wire and connect it to the battery’s negative terminal.

#5. Once all the wires are connected, you can reconnect the battery’s negative terminal.

#6. The final step is to test your radio to see if it powers on. If it does, you successfully wired the car radio to the battery.

If you want to wire your car stereo, so it turns on only when the key is in the accessory position, then you need to connect the red wire to the accessory wire in the dashboard.

This accessory wire is usually brown or black and can be found near the ignition switch.

#7. Once you have connected the wire, test the radio again to see if it turns on in the accessory position. If it does, you successfully wired your car stereo to the battery.

Should You Ground a Radio to the Battery or the Chassis?

One of the most common questions is whether you should ground the car radio to the battery or to the chassis.

The answer to this question is that it depends on your car. For example, some vehicles may require grounding the radio to the chassis, while others may require grounding it to the battery.

Personally, I prefer grounding it to the chassis as it is less likely to cause any electrical issues since the current draw by the stereo is low.

Can You Run a Car Stereo off a Battery Charger?

The short answer is yes, and you can run a car stereo off a battery charger. However, I would not recommend doing this as it is not suitable for the stereo in the long term.

This is because the voltage output by the battery charger is not regulated and may fluctuate, and the fluctuation can cause damage to the stereo over time.

If you want to run the car stereo at home, the better option is to use a power inverter. This will take the DC voltage from the battery charger and convert it into AC voltage.

The IMAYCC 110V AC to 12V DC Power Supply Transformer (link to Amazon) is the inverter I use at home mainly to test the speakers or different radios.

New Version Converter, IMAYCC 110V AC to 12V DC Power Supply Transformer Adapter Charger Max 600W 50A

One thing I especially like about this item is its connection simplicity. First, you must connect the positive and the negative stereo wires to the terminals and then plug the inverter into the wall socket.

This simple tool supports up to 50AMP, which is more than enough to connect any car radio.

Where Do I Connect Red Wire on Car Stereo?

In most installations, you should connect the red wire to the positive terminal on the battery.

In some cases, when you want to have better control over turning on and off the stereo, you may need to connect the red wire to an accessory wire in the dashboard.

The accessory wire in the car dash is usually brown or black and can be found near the ignition switch.

How Many Amps Does a Car Stereo Draw?

On average, car radio draws from about 2 amps to 10 amps, depending on the volume.

The 10 amps is often a top limit given by fuse and is used for the strongest speakers played at the maximum volume.

What Happens if You Don’t Ground a Car Stereo?

If you don’t ground a car stereo, it will not work. Car radio to operate needs to be grounded.

The most common way to do this is to connect the black wire of the radio directly to the negative terminal on the battery.

Sometimes, you may need to ground the stereo to the car’s chassis by connecting a black wire from the radio directly to a metal part of the car.

What Wire Is the Power Wire on a Car Stereo?

The wire that provides power to the car stereo is the red wire. In most cases, you should connect this wire to the positive terminal on the battery.

In some installations, you may need to connect the red wire to an accessory wire in the dashboard. The accessory wire is usually brown or black and can be found near the ignition switch.

Which wire Is the 12V Constant in Car Radio?

The yellow wire is the one that supplies a constant 12V power to the car radio.

In most cases, this wire is connected directly to the battery together with the red wire.

Tips on Wiring Car Stereo to Battery

#1. Always disconnect the battery’s negative terminal before working on any electrical components in your car. This will prevent any accidents from happening.

#2. Make sure the wire you use is thick enough to handle the current. I suggest using at least 16 gauge wire.

#3. If you are unsure how to wire your car stereo, consult a professional for help.

#4. Always test your radio after wiring it to the battery to ensure everything is working correctly.

Conclusion

Wiring a car stereo to the battery is not difficult and can be done by anyone with basic knowledge of car electronics.

Just make sure you use the proper wire size and follow the steps in this article, and you will be able to wire your car stereo to the battery in no time.