Car Audio Capacitor vs Battery

Car Audio Capacitor vs Battery

If you happen to inspect the interior of a car of any sophisticated music lover, then you won’t miss components such as midranges, subwoofer, crossovers, and high-power amplifiers. With these essential elements, your car’s audio system is perceived to be complete allowing you to enjoy high-quality music with enthusiasm. Now, although you’ll enjoy high-quality music, most people start complaining of low voltage conditions hence leading to the topic of car audio capacitor vs battery and which between the two can truly stand out.

If you’re a naïve driver, you’ll notice that your car’s electrical system, such as the headlights and the dashboard lights, tends to dim whenever your audio system plays heavy bass notes from the subwoofer. If you happen to visit your local audio expert, they will definitely tell you that the low voltage is ideally caused by insufficient current supply to your hungry amplifier.

The solution? Well, the answer lies in choosing between adding a secondary battery or a stiffening capacitor. Although this is a discussion that should have been planned way before you installed your car’s audio system, there’s a solution to it so please read on.


Car Audio Capacitor vs Battery: An Ultimate Guide

Do you Even Need a Secondary Power Source?

We are all different. While some people might require a secondary source of power to feed their high-end aftermarket audio systems, there are others who are less familiar with these demanding audio consoles. To them, adding another source of power besides their factory-installed car batteries might sound counter-intuitive.

This is, by the way, one of the main reasons why these factory-installed car batteries are unable to feed your aftermarket car audio system since they’re only designed to provide power for basic functions of your vehicles such as starting the engine and providing power to light up the headlight and dashboard lights.

Just to explain further, an ordinary car battery uses about 40 – 50% of its amperage to cater to basic electrical usage in your car saving the rest of the 50% energy. If you have a powerful acoustic car audio system, this remaining 50% amperage will basically not be enough to feed your high wattage amplifier.

This is, therefore, the main reason why your car’s electrical components such as the headlights and the dashboard lights will dim often whenever you play loud bass sounds. By the way, in a worst-case scenario, this rapid drop of electrical voltage might even damage your expensive car audio system or even reduce the performance of your subwoofer.

So, if you’re the one we’re talking to, then yes! You’ll definitely need to add a secondary power source to compensate for the rapid drop in voltage.


Understanding Electrical Power

Before we go deeper into this topic, we thought it would be nice if we could explain more about power ratings to make it easier for you to understand the various concepts related to batteries and capacitors. Now, in this topic, some of the common terms you’ll come across to are wattage, voltage, and amperage.

First, there’s voltage (V) which is basically the measure of electrical force. It’s actually more like pressure in a pipe. In most cases, car batteries are designed to offer at least 12V worth of power to be used by basic automotive electrical systems.

Next, there’s amperage (amps) which is referred to as the rate of flow of electric current. It’s more like the speed at which water flows through a pipe. To improve the amperage, or rather the rate by which electric current flows, you only need to increase the size of the wires and reduce the distance of electric flow to improve efficiency.

Finally, there’s the wattage which is the measure of electrical power. Also known as total power, wattage can be calculated by multiplying voltage by amperage.


What are Stiffening Capacitors and What are Secondary Batteries?

Now, this is where things start getting interesting. Briefly, a battery and a capacitor are not that dissimilar since they address almost a similar issue. Also, both of them are intended to store secondary energy which can be used when the need arises. However, they do have some notable differences that differentiate them from each other.

What’s a Capacitor?

For those who don’t know, a capacitor is a cylindrical (and in some rare cases rectangular) device that’s used to buffer electrical current very rapidly. These devices store energy but they release it very rapidly whenever the need arises.

The main reason why they’re preferred is due to their rapid charging and discharging advantage that allows them to frequently deliver huge bursts of energy whenever there’s a potential shortage.

What About Secondary Battery?

In most cases, a second battery is usually a high-capacity battery that’s more powerful than your factory-installed car battery. As we mentioned earlier, your car’s factory-installed battery is designed to address your car’s basic electrical demands.

So, to boost its performance, a secondary battery is added which provides plenty of reserve amperage enough to handle the influx of electrical demand by your car’s audio system. Although it solves the problem, there are various pros and cons you’ll have to deal with which we’ll discuss later on in this insightful guide.


What’s the Difference Between Batteries and Capacitors?

Now, both the capacitor and secondary battery are designed to store energy right? However, some major differences between these two sets them apart from each other. So, in this section, we’ll discuss some of those factors that set these two audio power sources apart.

First and foremost, capacitors are designed to store their charge or energy in the form of an electric field. On the other hand, batteries are designed to store their energy in chemical form. This difference in energy storage methods plays a key role in dictating the speed by which energy is discharged.

For the case of capacitors, their energy storage mechanism (electric field) is what allows them to charge and discharge really fast as compared to batteries. This hence makes them the best for powering demanding audio systems as compared to batteries.

Let’s assume your car is demanding more electrical power than what a capacitor can offer. In such a scenario, a powerful secondary battery will generally stand out as compared to a capacitor.

You see, since a car battery doesn’t recharge and discharge faster than a capacitor, it provides additional reserve power that can be used by your audio system alongside other electrical parts of the car without causing any voltage drop. For effective performance, always connect the primary and the secondary batteries in sequence.

Still, on the mode of operation, there’s another, quite hidden difference between these two energy storage units. This is only visible once you understand them better or when you go through a painful experience. Starting with the capacitor, we mentioned how excellent they are in handling short bursts of energy.

Now, this advantage can only be enjoyed when the car’s engine is running. This makes the capacitor a better option when listening to full blast music when your car is in motion. On the other hand, a secondary battery can store energy much longer making it the best to enjoy full-blast music even when the car is off.

In fact, a good example of scenarios where a second battery becomes an excellent investment is when you’re going out for camping or holiday/during a vacation in the countryside. In such cases, you’ll take a while before your engine starts (especially if you’re planning to spend two or three days). If you’ll be listening to music, a secondary battery will help to prevent your audio system from draining the primary battery.

However, if your itinerary only allows you to listen to music while on the wheel, then a capacitor is the better option. Why exactly? Now, when the engine is running, the second battery is recharged. By doing so, it will act as an additional load forcing the alternator to overwork in order to meet all the electrical requirements for all the loads. When I mention other loads, what I’m referring to generally are the headlights, dashboard lights, the two batteries (primary and secondary), and any other component that draws energy from the alternator.


Pros and Cons of Car Audio Capacitors


  • Illuminated Display: The first major advantage of car audio capacitors is the illuminated LED display. This digital three-digit display gives you a clear view of the current voltage of the capacitor to let you know whether the voltage is high or low.
  • Fast Charging: Since more capacitors are 1 – 10 Farad capacitors, charging them takes a very short time making them the best for delivering energy as fast as it’s needed.
  • Super Lightweight: Another huge advantage of capacitors is that they’re relatively light and compact thus allowing them to fit in the tightest of spaces.
  • Audible Tones: This is another huge feature that makes capacitors highly reliable. With audible tones, you’ll always be informed of cases such as reverse polarity, low and overvoltage.
  • Surge Protection: Most capacitors are designed with a high working voltage alongside surge protection that keeps them safe from extremely high voltage.
  • Attractive Finish: Last but not least, capacitors come with attractive chrome, aluminum, or black finish that allows them to blend well with most of your interior car parts.


  • Expensive: In most cases, car audio capacitors are considered much more expensive than batteries yet they perform the same function.
  • Large size: Some models of capacitors are much larger in size making it quite challenging to store them. Some have irregular molded shapes that make it difficult to fit them in tight spaces.
  • Complex Installation: When it comes to installation, installing an audio capacitor can be challenging as it requires a lot of technical know-how. This can make it easy to mess up along the way causing serious damage to your expensive audio system or the capacitor if you’re not careful.
  • Additional Strain: Just like the rest of your electrical systems, a capacitor adds more strain to your alternator as it requires to be recharged.


Pros and Cons of a Secondary Battery


  • Affordability: One of the main reasons why most people prefer a second battery to a capacitor is affordability. You see, a capacitor does the same job as a second battery but at a much higher price. So, instead of having to end up with a dent in your wallet, why not consider a battery?
  • Space-Saving: Another huge advantage of choosing a secondary battery is because batteries are more compact hence can fit in tight spaces where capacitors cannot.
  • Sufficient Power Supply: If you have a sophisticated car audio system, then your factory-installed car battery will generally struggle to feed your amplifier with power. As a result, most of the other electrical parts of the car will fail to function due to a rapid drop in voltage. So, to solve this common problem, a second battery will generally need to be added to generate plenty of reserve energy to power up your acoustic audio system.
  • Extra Power Source for Stationary Cars: So, whether you’re RVing or simply packing your car in a packing lot, one way you can enjoy your time is to listen to music. As a result, your battery might drain causing more problems.
  • So to prevent that, second batteries are added in the equation to provide extra power when your car is packed.


  • Leakage: One of the worst things about second batteries is that they can leak the chemical component to other parts of the car if mishandled.
  • Unnecessary Load: Just like in capacitors, a secondary battery recharges whenever your car’s engine is running. This leads to the overwhelming of the alternator, which results in straining of the battery.



Finally, choosing between a capacitor and a battery is a rather complex endeavor that seems complicated. However, to ensure that you make the right judgement, you’ll need to first understand the performance of your primary battery and the amount of extra power you’ll need to feed your hungry amplifier.

As we have already discussed in this guide, everything lies upon you to choose what you think will work for your audio system better. Whether you need a capacitor to take care of short bursts of energy or whether you need a second battery to provide ample power storage when the car is off, then it’s all totally up to you.

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