The importance of car audio capacitors and 4 things you need to understand

Updated Aug 16, 2022 | Same topic: Handy Maintenance Tips

Here’s everything you need to know about car audio capacitors, what they are, and what they do for your vehicle.

Innovators worked hard to give your stereo sound quality that you love. Every little part in it plays a particular role. If you’re missing even just one, you’ll probably end up devastated with the quality of your head unit. One of these underestimated parts is called the car audio capacitor.

Not a lot of vehicle owners know a lot about this particular part. Sometimes, even the savviest of them don’t know what a capacitor is for. Good thing is here to point you in the right direction. Today, we’ll help you understand what a car audio capacitor is. We’ll also tell you what it does and how you can tell if your car needs one. Find out all about it right here!

1. Car audio capacitors

In the simplest terms, a car audio capacitor is an electrical part that’s capable of storing energy. This can be compared to the regular batteries you see in everyday life. As a matter of fact, the very first “batteries” weren’t referred to as batteries. They were actually old capacitors.

The first capacitors were made from glass jars that were filled with water. The only difference is that capacitors are designed to discharge and store power very quickly compared to batteries. If used in car-audio systems, this capability can be tapped to provide your amplifier with an on-demand power source.

A car audio capacitor


A car audio capacitor is an electrical part that’s capable of storing energy

Most capacitors’ energy density is less than that of an alkaline battery. In fact, it’s even said to be a thousand times less! But a car audio capacitor is usually larger than those that you can find in usual consumer products.

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2. Car audio systems are power-hungry

You can use a capacitor to feed hungry amps if used in-car audio systems. This is because a powerful amplifier could possibly outstrip your car’s electrical system of its power-generating capabilities. If that happens, you may see your dashboard lights or headlights go dim while playing strong bass notes.

A car audio capacitor works by being supplied with voltage from the vehicle’s electrical system. This charges up the capacitor so that it has ample energy whenever it needs it.

If your amp suddenly needs more amperage than the amount your electrical system can supply, it can result in a noticeable voltage drop at your amp. But you won’t have to worry because your capacitor has your amp covered.

>>> FYI: Your car's electrical system and what you need to know when it shuts down

Car stereo

You can use a capacitor to feed hungry amps of car audio systems

Car audio capacitors are usually installed right next to the amplifier. If not, it is usually as close as space or system allows it to be. This is why there are fewer voltage drops. This is also why most electrical systems continue to operate normally. Capacitors are also able to discharge and charge rather quickly. This is what makes them easier to “refill” in case your amps need extra power.

A car audio capacitor

A car audio capacitor works through current supplied by a vehicle’s electrical system

3. Does your audio system need a capacitor?

If you have a battery, a stock charging system and a powerful amplifier, you may need a stiffening cap. Unfortunately, adding a capacitor to your in-car audio won’t have too much of a difference. This is unless a few very specific criteria are met.  Here are some of those main reasons to need a capacitor:

  • An extremely powerful amplifier
  • A low-capacity car battery
  • An underpowered alternator
  • Excessively low or long gauge amperage power wire

high performance audio system


You can use a car audio capacitor to help provide power to high-performance in-car audio systems

The most important sign that you need to check is dimming headlights. If your headlights suddenly go dim after turning up your radio, your charging system may not be up to the task. This could also be the case if the lights go dim in loud bass parts of the audio.

The problem is that a stiffening cap is not a guaranteed solution to the problem. If either the amp is too demanding or the charging system is underpowered, a stiffening cap might not solve it.

>>> Also check: What you need to know about car audio and amplifiers.

4. What is a stiffening cap?

Installing a vehicle audio capacitor actually isn’t difficult, but the task can be fairly dangerous. Large caps are capable of discharging and storing a good amount of energy. This is why you need to be a little bit more careful when handling them.

In fact, this is one of the most fragile parts of most car audio components. If you decide to buy a cap, remember that it should come with installation instructions and safety precautions.

stiffening cap

If you decide to buy a cap, remember that it should come with installation instructions and safety precautions

It should also come with a resistor or a light bulb that can be used to discharge the device. If you have never tried installing a stiffening cap before, read all the guides carefully. Car audio capacitors should be installed as close to the amplifier as possible. These will usually have one or two terminals. In some cases, it has a distribution block.

Hanna Sanchez

Hanna Sanchez


Hanna is one of the most competitive swimmers in the country during her day. It was not long before she discovered her passion for the automotive industry as well. Nowadays, she balances her passion through writing as well as coaching.

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