Car audio capacitor or second battery: Which one to go for? | Autance

A common query that we receive after the installation of a high-end aftermarket car audio system is about a lack of power affecting performance. People may find that their headlights are dimming or that their audio system is not performing as it should. Ideally, this is something that would have been discussed and anticipated when…

  • 9351
Car audio capacitor or second battery: Which one to go for? | Autance © Car audio capacitor or second battery: Which one to go for? | Autance

A common query that we receive after the installation of a high-end aftermarket car audio system is about a lack of power affecting performance. People may find that their headlights are dimming or that their audio system is not performing as it should. Ideally, this is something that would have been discussed and anticipated when the car audio system was being planned but that is often not the case. The answer to this problem lies in choosing either a capacitor or an additional battery for your car, with both options having some pros and cons that need to be understood.

1. Do you really need to add an extra power source to your system?

For people that are not too familiar with demanding car audio systems, it can seem counter-intuitive to them that their car battery is not powerful enough to provide the necessary juice to their system. There are a couple of factors to be considered here.

The first and foremost is the fact that factory-installed car batteries have only enough power for the basic functions of the car with a little bit of leeway left over. It is simply not in the car maker’s benefit to sell cars with high-performance batteries that will be left unutilized by a large percentage of their customers.

Now, in general, close to 40-50% of the amperage of your battery goes towards powering the electronic systems in your car and making sure that there is enough juice to start the engines at all times. The remaining 50% of the factory-installed battery is just not enough to power a high-end aftermarket car audio system.

The amplifier is particularly power-hungry and will demand an extra source of power to function at its optimum performance.

So how do you know that you don’t have enough power? The car will start to experience some electrical issues where the windows may not get rolled up at the same speed they used to or the headlights of the car start to dim when the car-audio system is booming.

Most often, though, it will lead to a reduction in the performance of the car audio system. This is the worst-case scenario because it does not matter how much you spent on getting the best quality audio components installed in your car if they just don’t have enough juice to be able to do their job to the best level.

So, yes, if you are adding a high-end car audio system, be prepared to add another power source as well.

car battery , car audio capacitor

2. What are a car audio capacitor and a second battery?


Car audio capacitor

 At the most basic level, a capacitor and a battery are not that dissimilar because both of them are used to store energy. The difference, though, is that capacitors have the ability to discharge this stored battery very quickly if the need arises.  In a car where a high-end audio system has been installed, this ability of the capacitor is very useful since the sudden burst of energy can used to feed the power-hungry amplifier. This helps reduce the problem of dimming headlights when the bass really hits but may not actually solve it completely.

Second Battery

Choose capacitors or second battery

 A second battery to double the amount of power that you have stored can help solve the problem of headlights dimming or the car audio system not performing to its optimum. The reasoning is pretty simple here.  Adding a second battery provides plenty of reserve amperage to the system and can also be placed very close to the amplifier. It is slightly more complicated than just replacing your factory installed battery for something that is powerful enough for your needs but it is definitely the less expensive option in this case.

3. What’s the Difference Between Batteries and Capacitors?

Choose capacitors or second battery;
What’s The Difference Between Batteries And Capacitors

There are plenty of differences between the manner in which batteries and capacitors in the manner that they are designed and function. Both of them are designed to store electric energy, yes, but the differences in how they perform this task are very important.

The potential energy or charge inside a capacitor is stored in an electric field whereas the potential energy in a battery is stored in a chemical form. This chemical form of storage allows much greater densities and thus batteries capable of holding the same amount of electrical energy as a capacitor will be much smaller in size.

This storage method also dictates the speed with which the electric energy can be released. In the case of capacitors, this is much more rapid than batteries and can be a big advantage when it comes to powering car audio.

The cost is also a major consideration in this case. People may want to save money since they would have already spent quite a lot on the high-end car audio system as well. An additional battery is going to be much more reasonable than a capacitor even with the installation costs being taken into consideration.

4. Pros and Cons of a Car Audio Capacitor


  • The biggest pro of using a capacitor in the car is the availability of instant high-power when you need it.
  • A capacitor will reduce the problem of dimming headlights
  • They charge faster than batteries
  • Significantly less amount of voltage drops since they are usually installed next to the amplifiers.


  • Capacitors are much more expensive when compared to batteries while in essence, they do the same job.
  •  Since capacitors are a much lower-density energy storage option, they are often quite large in size. This can be a problem in a car where the space available is at a premium.
  • A capacitor is just another thing that the alternator needs to charge and so puts additional strain on the system
  •  The capacitors compete with the amplifiers for power until it is fully charged and this can actually affect the functioning of the car audio system in certain situations
  • The capacitor can also drain some power away from the subwoofer.
  •   Installing a capacitor requires much more technical know-how than installing a battery in the car and thus there is that much more chance of something going wrong.

5. Pros and Cons of a Second Car Audio Battery


  •   Installing a second battery is the most common option used by people looking to power their car audio system in a large part because of the cost involved. A car battery is significantly less expensive than a capacitor
  •  Since batteries are a high-density energy-storing solution, they require much less space than a capacitor would provide the same amount of electricity storage.
  •  Adding an additional car battery will not only reduce the problem of dimming headlights and other electrical components but eliminate it altogether
  • Batteries are easily available at many locations and come in a wide variety of different sizes.
  • Adding a secondary battery is a much more permanent solution to the lack of power problem
  • It adds permanent power storage to the car that can be used for other purposes as well if so required


  • The low-cost car batteries run the risk of corrosion and leakage of their chemical components.
  • The need to charge an additional car battery is also a strain on the engine
  •  Adding a secondary battery may be less expensive than replacing the older one for a high-capacity one but requires more technical expertise.

6. Identify the right capacitor or battery for your car

Choose capacitors or second battery;

Buying the right capacitor or additional battery for your car means knowing a bit about the battery you have installed and the amount of power your car audio demands. The first thing to do is to find out the amperage of your factory-installed battery. As mentioned earlier, deduct about 50% of that for the running of your car electronics and cranking the engine up. The remaining is what you have available to you for the car audio.

Choose a capacitor if your electrical problems are minor but your amplifier is not getting enough power at all times. A capacitor is perfectly suited to solve this problem because it can be installed close to the amp and supply with a boost of power when it needs it most.

Since the amp can function at an optimum level most of the time, it helps improve the quality of sound that you have been getting from the system. Generally, 1 farad of capacitance is added for every 1000 watts RMS of system power, but people may choose to up this to 2 or even 3 farads as per their liking.

If you are struggling with electronic problems, dimming of headlights and other issues then choose a secondary car battery that adds a significant electrical storage unit and allows everything to run smoothly. This option sets you back a lesser amount of money but does bring with it the headache of battery replacements and maintenance, depending upon the kind of battery you install.

A secondary battery requires lesser space and also comes in different shapes and sizes so which affords you a bit more flexibility.

Final Thoughts

Deciding what kind of secondary power unit you want to install in your car may seem like a complicated decision at first but assessing the pros and cons of each option will help you make that decision. It is, however, something that is a must-do if you want to get the most out of your expensive, high-end, car audio system.

Commnets 0
Leave A Comment