Skip to Content

Do I Need a Car Audio Capacitor?

A car audio capacitor is a device that stores and releases electrical energy.

This energy can be used to improve the sound quality of your car stereo system by providing power to the amplifiers when they need it the most. 

But do I actually need to add a capacitor to the car audio system? Let’s find out.

The main reason to use a capacitor is to improve the sound quality of your system by providing power to the amplifiers when they need it the most. This is especially important if you are using high-powered amplifiers that require a lot of current. As a general rule, 1 Farad of capacitance should be added for every 1000 watts RMS of system power.

Also, a capacitor is needed to protect the audio system from damage caused by sudden spikes in voltage when playing bass-heavy music.

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

Tip: If you are unsure whether or not a capacitor is suitable for your car audio system, it may be wise to consult with an experienced audio technician or equipment manufacturer who can help you determine the best solution for your needs.

At the end of the day, choosing a capacitor for your car stereo should be based on your personal preferences and priorities around sound quality, power, and safety.

The selection of the capacitors is impressive. It starts from small 1F NVX XCAP1F and goes up to the large models like the fantastic 30 Farad Rockville RFC30F (links to Amazon).

In the article below, I will go into more detail about how capacitors work and when they are actually needed. I will also provide some recommendations on what size and type of capacitor to choose based on the power of your car stereo system.

What is the car audio capacitor?

A capacitor is an electronic component that takes, temporarily stores, and discharges electrical energy rapidly. In the car audio systems, the capacitors are used to supply the amplifier with a quick jolt of power so that the lights do not dim when the bass or loud music plays.

All capacitors have two electronic conductors and a dielectric. The dialect insulates the two conductors, so when the conductors are powered from the source of electricity, the static energy generated is stored around the dialect.

The capacitors simply ensure that the amplifiers function efficiently. Various brands of capacitors in the market come in rectangular shapes and others in cylindrical shapes, but their functionality in terms of the power storage capacity and speed in discharging the needed electricity, is what determines how good a capacitor is.

The capacitor value is indicated in farad (F) or volts (V), which a measure of capacitance. Capacitance can be defined as the energy a capacitor has at a given voltage.

do i need car audio capacitor

Most manufacturers make capacitors able to handle larger voltage than the audio system needs, just to be safe.

What Do Capacitors Do for Car Audio?

In car audio, large outboard capacitors, also called stiffening caps, prevent lights from dimming when loud bass notes play.

They accomplish this by supplying the amplifier with a quick jolt of power.

Capacitors work almost the same as batteries, but they can release energy rapidly, making them ideal for car audio systems. But most importantly, audio capacitors support the battery and stabilize voltage in the car.

When do I need a capacitor for car audio?

  • If your car has large amplifiers that draw large currents, then you will benefit from an audio capacitor.
  • If you are a big fan of music with strong bass, then you will need to get a car capacitor.
  • If your electrical system does not have additional reserve capacity, a capacitor will be beneficial.
car audio capacitor in trunk

A good indicator that you require a car capacitor is the dimming of headlights. When the electrical system of your car is unable to supply voltage to your vehicle quickly, you will notice that the quality of the light and the music are not as great.

The loud music will translate to dimming headlights since more current is directed towards the speakers. This means that your car’s electrical system cannot provide a quick jolt of power to restore the dip caused by the stereo, and thus you will need to get a capacitor.

A capacitor ensures that when your car stereo amplifier soaks up a high amount of voltage, the quality of the music and lights will not be compromised, and your car can perform at its best. This is because they can store energy and quickly release it when such rapid surges occur.

What are the types of capacitors for car audio?

  • Carbon capacitors differ in their ability to hold power. The carbon capacitors are best known for holding more power, unlike the other types of capacitors. They are, however, slower in recharging compared to the electric capacitors.
  • The electric capacitors are excellent and faster at power recharge but a little less on the reservation of power. The electric capacitors generally come in the round canister and use one farad for 1000 watts of power.
  • A hybrid capacitor is a blend of the electric and carbon capacitors and mostly come at a higher cost. They are great, especially when you feel the need to have a second battery.

When you are buying a capacitor, there are key indicators, you should look out for:

  • The value rate measures the amount of charge a device can store in terms of Farads. This is one of the most important things to look out for when purchasing your capacitor. The more powerful your amplifier is, the more Farads you will require.
  • Surge value. You will need to be cautious when buying a capacitor is its surge voltage values. A capacitor that exceeds the surge level could be destroyed, and getting one below its surge level would lead to a short.
  • The number of terminals. A capacitor with more terminals always comes in handy. The normal small ones usually have two terminals while the larger ones come with more. Additional terminals can allow you to utilize it as a distributor block, making the installation of the hardware easier.

Which capacitor should I choose for my car stereo?

It is advisable to install your car audio system before installing the capacitor so you can assess the need for capacitance.

There is a wide range of capacitors in the market today. When you are wondering how to choose a capacitor for your car audio, you will just need to know which best suits your car audio system.

Once you know the total power of your audio system and the number of the amplifiers, you can choose the most suitable capacitor for your car. In general, we use a 1F capacitor for each 1000W of the car audio power. However, there is no harm in using a larger value capacitor, and in fact, it is beneficial. The larger the value of the capacitor, the better it is in sustaining the amplifier’s next hit.

Note that capacitors are compatible with all brands of amplifiers. Just ensure you get the watts value right.

Some of the top brands of capacitors that I can recommend:

  • Rockville – This company that also builds audio equipment such as amplifiers and speakers focuses on providing high-quality amplifiers. Their popular capacitor is the Rockville 4 Farad Car capacitor.

Rockville RXC2D 2 Farad Stiffening Capacitor + Rockvile RWK41 4 AWG Amp Kit

Rockford RFC10HB 10 Farad Hybrid Digital Capacitor

  • Stinger – Being in business for over 30 years, Stinger is responsible for manufacturing one of the best brands of capacitors in the market. They also make car audio accessories such as batteries, subs, and wiring kits. One of their great products is the 5 Farad Stinger Pro Hybrid Capacitor.

Stinger SPC505 Pro Hybrid 5 Farad Capacitor , Black

Essential things you should consider when purchasing a capacitor:

  • Get a capacitor that has low and high voltage protection and has an automatic shut- off. This will ensure it lasts for an extended period of time without wearing out.
  • You need to pick a capacitor that charges fast, not more than a minute. A capacitor that takes time to charge may over-heat and break.
  • Choose one that has a LED display, so it would be easy for you to keep an eye on the amount of charge.

Safety precautions when working with capacitors.

As much as we have heavily glorified the use of car capacitors, there a few cons to them.

  • When capacitors are exposed to very high voltage, they are likely to overheat and explode. It is important to get the correct capacitor depending on your audio system power to avoid such incidences.
  • Capacitors may cause shock because even after power has been removed, capacitors may still retain charge for a long time. If you need to move your capacitor to another car, you have to discharge it properly

How to discharge car audio capacitor?

To discharge the capacitor you can use the 12V test light and touch both the negative and positive terminals. Ensure you have protective gear on as the test light may get extremely hot and pop.

You can also discharge the capacitor by removing the main fuse on the power wire close to the battery of the car that connects the capacitor and amplifier. The capacitor will now act as the battery. Play your music until the amplifier goes off, and you can be sure the power is used up.


Do not connect the negative and positive terminals of the capacitor using a screwdriver or wire as it could damage the capacitor or even injure the handler. Use the test light or resistor.