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Do I Need a Capacitor For My Amp? [5 Reasons To Add One]


If you are asking yourself: Do I Need A capacitor For My Amp? Then you are in the right place! We will give you all of the information that you need to make an informed decision.

A car capacitor is an electronic device that supplies that extra power to the electrical system without the need for buying any additional batteries. A capacitor is able to do this because it can store and discharge electrical energy very quickly.

Do the car lights in your car dim every time the music plays loud bass? You see, car audio capacitors are a piece of electronic component that helps regulate the flow of electricity throughout the unit.

You might need a capacitor to help you with this issue. However, If you have a damaged capacitor installed in your sound system, it could cause all types of problems for the car stereo.

In this guide, we will talk about what a capacitor is and how it impacts your car’s audio system. We will also present useful tips and other details you may need if you ever need to change yours.

What is a Car Audio Capacitor?

BOSS Audio Systems Cap 18 Capacitor

Capacitors (also referred to as condensers) are devices that store electrical energy. When they’re used in audio systems, they function as energy reservoirs or line filters, or both at the same time.

A capacitor could also be defined as an electrical component with two terminals made by two conductors or electrodes separated by an insulator. It enables current to flow through under specific conditions while blocking it otherwise.

What’s the Difference between a Capacitor and a Car Battery?

You may be wondering about the difference between a car’s battery from a car audio capacitor. Keep in mind that a car capacitor is often used in circuits where there’s a high supply voltage or high frequency.

Car capacitors can be utilized to store and release electricity. The charge of car capacitors will be dissipated easily if the circuit isn’t connected to an antenna, while if it’s connected to an antenna, the charge will last longer.

A second battery features lead plates inside it that store electricity and offer energy for the car’s electronic components when the engine is not running. The high-output alternator in your engine charges the battery up when you’re driving.

Leaving the lights on in your car for a long time means the charge in your battery will drain down quite far. A car audio capacitor could be charged up right away, then released as necessary for short periods.

When Should You Add a Capacitor to Your Car Audio System?

Here are some of the instances where you use an audio capacitor in your car stereo.

Voltage stability

Car audio capacitors provide a small amount of protection for car amplifiers from possibly damaging under system voltage surges over time if you play loud bass notes play. However, most of the reason for adding a capacitor to my car is to keep the voltage stable.

Before you consider adding large outboard capacitors, make sure you have a strong battery and high-output alternator power for the total amperage of the sound system. Always check your wiring to make sure you have sufficient-sized power wires.

Voltage drops may happen if the gauge isn’t sufficient. If the charging system of your car doesn’t supply current for the combined RMS rating of your amplifier, there are no amount of capacitors that will keep the electrical system from having voltage drop problems when run at RMS output.

Sizing caps

A car audio capacitor comes in different sizes, starting with one farad. The rule is to add one farad of capacitance for every 1,000 watts of system power. Take note that it doesn’t hurt to utilize more capacitance than this law, and most systems utilize two or three farads per 1000 watts RMS.

Install your car audio capacitor near the subwoofer and amplifier as possible to cut the path needed for an extra power surge. Follow all the necessary directions for mounting and wiring to make sure efficient and safe use.

Remember that continued voltage drops which last more than a second or two might not be helped by the addition of a car audio capacitor. In such cases, it may be better to include extra to the car audio system or update your car’s alternator.

Use for caution

The stored content of the capacitor can provide a shock if mishandled when it’s fully loaded. Follow all the directions and ensure the cap is drained before contact. A light bulb or resistor can be wired across the cap’s terminal to enable the car audio capacitor to discharge safely and slowly.

Bear in mind that a large capacitor doesn’t make your car audio system sound louder. What they do is enhance the performance of the sound system by minimizing distortion caused by sudden voltage drops.

Adding capacitors for more power

A car audio capacitor stores energy as immediate power for the amplifier. If the amplifier draws more energy than is available from the electrical system directly, the extra capacitor covers the difference up to its stored capacity.

Also, the battery isn’t overloaded, and the car voltage keeps steady. The capacitor will help guarantee your music doesn’t go flat but has the sound quality you always love.

Large wattage car audio systems

Remember that high wattage car stereo system has a high current draw. It can draw high amounts from your car’s electrical system. Bigger, multiple amp systems are even a major drain on the electrical system.

In most cases, it depletes the current capacity and thus reduces the voltage far enough that it can’t sufficiently supply the amplifiers. Adding capacitors to your car audio system could help fix this issue.

Important To Know When Buying a Capacitor for Your Car Stereo

Rockville RXC4D Car Audio Capacitor

Buy a capacitor that has protection against low and high voltage. It must also have an automatic shut-off in case of an electrical surge. You need to pick a capacitor that charges quickly, not more than a minute.

A car audio capacitor that takes time to charge may overheat and break. Pick one with a display that provides the amount of power consumption, so you can keep a close eye on it. Make sure you use a chassis ground wire that’s thick enough to avoid any electrical issues.

Headlights dimming is another sign that you need a car audio capacitor. Adding special capacitors called stiffening caps is the best solution to prevent lights from dimming. These capacitors work by storing small amounts of energy that can help stabilize voltage fluctuation.

When mounting the ground, ensure to scratch all the paint of the chassis and create a shiny surface for the ground wire to get a good connection. This way, you can guarantee the amplifier will get a quick jolt of power.


Q: How can I safely work with a capacitor?

When using a car audio capacitor, there are important considerations you need to remember. Do you have a strong car audio system? Then your capacitor may overheat and explore. It’s essential to pick the proper car audio capacitor based on how strong the system is so you do not get any unpleasant incidents.

Are you working on something in your vehicle that removed the power but forgot to discharge the capacitors? You could get an unpleasant shock. Should you move those capacitors around, make sure you discharge them first.

Discharging ultra-capacitors is challenging. To safely discharge it, you can use a test light and touch the (two poles) positive and negative terminals. All the lights will get hot, so always wear protective gear.

You could also discharge the capacitor by getting rid of the main in-line fuse on a power wire connecting the battery to the amplifier. Mount capacitors as close to the amplifier as possible using short wires. It’s a good idea to use the same bolt on both the ground and the amplifier.

Q: How can you charge a capacitor?

You will need a voltage source and a resistor. You can utilize a series of resistors to control the current through the car stereo capacitor or a single resistor, which is rated for high power.

Also, the standard unit of capacitance is farad. A one-farad capacitor will take a second to charge with one amp of current.

To power a capacitor, you must connect it to an electric source by using a resistor or a wired light bulb. The light bulb regulates the flow of energy and is usually included with the capacitor when you purchase it.

To complete the circuit, connect one end of the resistor or light bulb to the capacitor’s positive terminal and a ground wire from the other side to its negative terminal. Some units come with a built-in distribution block. If this is the case, you will need to ground separately.

Q: How can I charge a car audio capacitor without a resistor?

If you need to charge a capacitor but don’t have a resistor, feel free to use a lightbulb. You need a 12-volt light bulb and a light bulb socket to do this.

Follow these steps to charge up your car stereo capacitor with a light bulb:

  • Put the capacitor for my car close to the battery.
  • Attach the negative terminal of the capacitor to your car chassis.
  • Hold the test light in place between the capacitor’s positive terminal and the battery’s positive pole.
  • Hold that connection for a few minutes.
  • When the capacitor is charged, your test light bulb will go out.

When your car audio capacitor has total power and is fully charged, you can easily tell by checking the current value on the voltmeter display. You can also utilize a multimeter. A fully charged car audio capacitor must be more than 13 volts.

To check the capacitor’s voltage with a multimeter, connect the positive probe to the capacitor’s positive terminal and the negative terminal to the negative probe. The figure that appears on the screen is the specific voltage of your car audio capacitor.

Q: How many times can an audio capacitor be charged?

Capacitors are often utilized in power supplies. They store energy and release it when necessary. The main problem with capacitors is that they’re discharging over time.

Most capacitors will indicate the amount of charging cycles they can handle. It would be best if you chose one with a higher number of cycles because it will last longer. Some brands claim their capacitors can charge/discharge from 100,000 to 1 million cycles.

Q. Do capacitors provide more power to the electrical system?

Typically a capacitor is added to your sound system because the alternator and small battery were not designed to produce so much power in a short amount of time.

The capacitor steps in and provides more power, so the system does not get damaged. However, some capacitors are not so great when it comes to solving the dimming lights problem.

If your electrical system is not providing enough power, then you may need an extra battery or alternator with a higher voltage rating. Depending on the setup, most experts would prefer adding additional batteries to solve the dimming problem.

Final Thoughts

Overall, there’s no doubt that a capacitor is one of the most crucial parts used in a car stereo for a better sound quality experience.

Choosing a loud and bass-heavy car stereo system for your car is a nice thing, but it can interrupt other car components, such as car lights, the engine’s alternator, or the battery.

Thus, pick a high-quality capacitor to get rid of the issues with your car’s operation. It will also store enough energy for other activities.

Even though the capacitor stores power, it does not act the same as a battery. Some ensure that you are following the necessary steps to charge the cap safely.

We hope you found this article helpful. If you have any further questions, please feel free to ask in the comment section below.

Last Updated on: June 13, 2023

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