What does a Car Audio Capacitor Do?

Few car owners are very knowledgeable about this specific component. The most knowledgeable among them occasionally have no idea what does a car audio capacitor do. Fortunately, we can guide you on the proper route because we are here. We’ll explain what a car audio capacitor is to you today. Additionally, we’ll explain what it does and how to determine whether your automobile requires one. Learn more about it right here!

What is Car Audio Capacitor?

A backup battery is analogous to a car audio capacitor (also known as a stiffening cap). It stores energy that will be released when a rapid, significant voltage change necessitates giving the car’s voltage a little boost.

Car capacitors act as a buffer to stabilize the system up to its maximum capacity only. When used, the load in the capacitor gets recharged as soon as possible.

A car capacitor works similarly to a regular electronic capacitor but is much larger.  

Need Of An Audio Capacitor In Car

High-tier amps produce the best stereo music quality. However, these amps also eat up a bit of the car’s supply. 

Soft music doesn’t consume much power, but heavy bass does. Hence, if you play a song with full-on bass, your headlights might start to dim. The dimming happens because the amp needs more energy to produce those bass sounds (or any power-hungry sounds in particular. 

An audio capacitor increases the electrical system’s power output. Giving the car’s electronics more power while keeping the amp at a minimum avoids any headlamp fading from happening.

A car audio capacitor might be a wise choice. Even with a weak alternator, a limited-capacity car battery, or wiring with little amperage, it improves the sound output.

The issue of power scarcity during high-fidelity music playback is not addressed, though.

Capacitor Installation

You should be aware that a cap can be dangerous if you don’t have the instructions for your capacitor. It has the power to fast charge and discharge energy to the point where it can melt its insides and forge metal objects like tools and jewelry.

It’s safe because a new cap is sent discharged. Usually, the package comes with a resistor or connected light bulb. A bulb or resistor connected across the capacitor’s terminals enables a slow, secure discharge of the capacitor. The same bulb or resistor is also used to charge up the cap securely but with a different wiring arrangement.

1. As with any car electronics installation, begin by removing the ground line from the battery. Remove the in-line fuse from the power cable for the amp near the battery in this installation.

2. Use the shortest wires to connect a capacitor to the sub amp as close as possible. For the additional charge to reach the amp quicker, it must travel less distance.

3. To prevent the cap from becoming a hazardous flying object in the case of an accident, ensure that it is mounted firmly.

4. Positive and negative poles make up a capacitor. They ought to be written on the capacitor. The positive is wired to the same positive power line that leads to the positive, 12-volt socket on your sub amp. Use wire that is the same gauge as the amp’s power supply. With the aid of a distribution block, this is possible. The cap may also occasionally have numerous connection terminals, which makes it simpler to wire into your system.The several terminals function as a distribution  block. 

For example, you can connect the power wire from your battery directly to the positive terminal of the cap and can then use a short cable to connect from there to the positive power connection of the amplifier. 

5. Like the amp, the capacitor’s negative pole is connected to the chassis ground. Using the same bolt the amplifier uses for setting is the best procedure. 

6. Ensure the connections are clean and tight and that all paint has been scraped off the area where the chassis ground will be placed. It would help if you then charged your capacitor. If carried out too hastily, the cap can “pop,” causing damage.

7. You’ll need to buy one if you don’t already have the original charging/discharging resistor or light. The best option is a 12-volt vehicle test light with a bulb, not a tiny LED. A high-wattage, low resistance resistor, readily accessible at most electronics parts stores, provides an alternative. Get one with a rating of 1-20 watts and a value of 10-1,000 ohms; the exact figure is not important. The wattage should be larger the lower the resistance.

8. Connect the two terminals of the amp’s in-line fuse holder to the test light or resistor (where you took the fuse out earlier). Reconnect the ground cable on the automobile battery. While the cap charges, the resistor will heat up or illuminate the bulb.

9. The light will eventually go out, or the resistor will begin to cool after 10 to 30 minutes. Carefully remove the light or resistor; they can become quite hot. A minor spark may occur as you change the fuse; this is normal, but it should remind you of the electric solid forces at play. Your capacitor has been put in place.

Advantages of Audio Capacitor

They’re a cheap fix for shoddy wiring, like when you power a 1,000-watt subwoofer amplifier with the factory wiring harness, which is never a good idea.

You can find Cheaper capacitors with low farad values for less than $50.

They can lessen electrical noise that reaches the amplifier and are helpful for particularly long 12-volt cable runs.

Disadvantages of Audio Capacitor

A capacitor may worsen the situation if your alternator isn’t strong enough to power your stereo system and the amplifier channels. This is because a capacitor can’t produce more power than your alternator and charging system can provide and because the capacitor absorbs some voltage and current right after a bass hit, lessening the bass’s impact after a few seconds of loud bass notes.

They’re not a fix for very high current subwoofer amplifiers in a car with too small an alternator, meaning the alternator has too little actual amperage output.

The cheap ones contribute to battery drain when the car is turned off and may result in a weak battery after a few weeks if the vehicle isn’t driven or recharged often enough.

The high capacity, good quality capacitors (more than 5 farads) are expensive, about $100.

Frequently Asked Question

Which size capacitor should I purchase?

As a general rule, one farad of capacitance should be added for every 1,000 watts RMS of system power. However, employing bigger value caps does not have an electronic cost, and many people benefit from using 2 or 3 Farads per 1,000 watts RMS. The amp has more charge available to it when it needs it the greater the cap.

How long do the capacitors in automobile audio last?

Car audio capacitors have two to twenty years; a lot depends on the capacitor’s manufacturer and the driving environment. You might want to replace the capacitor because its capacity will decline over time and become less and less helpful.

What difference do audio capacitors make?

Different brands of caps certainly have a distinct sound, but this does not imply that the sound will necessarily be better—whatever that term “better” means—as something with better statistics might not be as appealing in terms of sound.

Does automobile audio require a capacitor?

Only if your automobile experiences power surges, which are frequently indicated by the dimming of your car lights, do you require a capacitor for your car stereo. The capacitor is a temporary fix if you experience power spikes frequently. You should consider boosting the current capacity or adding more batteries in this situation.


Before buying a capacitor for your car, you must know what does a car audio capacitor do. Most individuals won’t require a capacitor for their car’s audio system, but you might if your system uses a lot of power. As we previously stated, a high-capacity battery or additional batteries may be better than installing a capacitor if you have frequent power surges.

After reading this article, I hope you get full information on capacitors’ role in car audio systems, their advantages, disadvantages, and when you need them.

If still, you have any queries, drop them in a comment box. We will love to solve it. For more information related to amplifiers, subwoofers, and speakers, check out our related articles.

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