# When Do You Need a Second Battery for Car Audio?

Wondering whether you need a second battery for car audio or not? A rule of thumb is to look for specific indications. If you are facing a slower window roll-down speed or dimming headlight and you are also a user of heavy duty car audio, you probably need a second battery.

A dual battery can also improve the excessive corrosion condition of the terminals and can improve decreased vehicle performance. You’ll also need a second battery for car audio if you’re using any heavy audio system above 1000 watts RMS or playing for a long time with the engine off.

But before you make up your mind, let’s explore if other measures can solve your problem.

## When Should You Go for a Second Battery?

Adding a second battery for your car audio system depends on how much stress you put on your battery. Typically, a car battery can run stereos for 2-6 hours, but using a battery at its full capacity drastically reduces its lifespan. You may need to run the battery at only 50% of its capacity to avoid this situation. That should give you around half an hour. But if your non-essential function requirements exceed 1.5 hours, you really need to consider an extra battery.

Last but not least, you will regret not upgrading your battery if you love listening to audio while in parking and going on frequent long drives or camping.

## Does Bigger Car Audio Mean Bigger Car Battery?

We’ve got you covered with the most straightforward approaches to calculate the battery size you need.

The system’s total RMS wattage should be the same as the battery’s cranking amps.

Suppose your car’s total RMS Wattage of the system is nearly 1000 watts. Then, you should go for at least 1000 cranking amps battery for your car’s audio system.

If your system load is 2000 Watts, including stereo, and you want a minimum running time of 2 hours, then you can calculate the batteries’ minimum reserved capacity accordingly with the formula-

Reserved capacity (in Amp-hours) = {Load power (in Watts) x Operating time (hours)} / 10

= (2000 x 2) / 10 Amp-hours = 400 Amp-hours

In this case, your stock battery and the second battery should produce 400 Amp-hours.
There are a few other ways to calculate the required size of the second battery, each being more complex than the other. But these two are the easiest possible solutions.

The efficiency of the machinery, volume levels, and other factors can affect the actual power usage. If you need more clarification, you should speak with a car audio expert or technician who may recommend the correct battery for your requirements.

## What are the Problems with an Extra Battery for Car Audio?

You may think two batteries are always better than one, but that is not always the case. Two batteries means twice the load for the car. It creates more pressure on the alternator to produce the current for a smoother audio experience. If the extra battery discharges current greatly, it can overwhelm the alternator.

Each component of a car that consumes electricity is a “load.” The more immense an accessory is and the more power a component consumes, the bigger the load becomes. Loads can include basic components like headlights, ignition systems, air conditioning, and more advanced features like infotainment, GPS, and robust aftermarket audio systems.

A single battery can weigh 20-25 kg, and an additional battery means increasing this weight. As a result, there is fuel inefficiency and the possibility of damage to the overall vehicle dynamics. Better-performing car batteries can surely solve them, but they and other installation equipment like cables, terminals, and isolators come with a premium price. Batteries are also bulky in size, which makes it harder to accommodate them in smaller vehicles.

## Alternator or Capacitor – Right Option for Car Audio?

The alternator’s primary purpose is to generate electricity when the engine runs. It supplies consistent energy to other electrical components and car batteries. The car will soon drain out the battery when the alternator stops functioning somehow.

A capacitor can store and disperse current at a moment’s notice. They are usually placed near the car’s audio system so that they can rapidly deliver electricity. When the stereo plays high notes or base, there is a quick demand for electricity. The capacitor meets those demands quickly and prevents probable system crashes. They are very useful for short-term crises but cannot serve in long-term power supply.

The key difference between an alternator and a capacitor is that an alternator generates power for the car to function and recharges the battery. On the other hand, the capacitor supplies quick and short-term current, which the alternator and the battery cannot do.

## Alternatives of Adding a Second Battery for Car Audio

You can explore several alternatives if you cannot manage a second battery for your car audio system.

For example, if you cannot accommodate a new battery, you can replace the older battery with a larger and high-capacity one. You can choose from higher Amp-hours or opt for specialized deep-cycle application batteries.

Another possible measure is to upgrade the alternator for faster battery recharge. A more powerful alternator can generate power more efficiently and can simultaneously supply it to the functional electrical components.

Another good alternative to a second battery is the efficient use of car stereo. A higher sensitive speaker can produce more sound at any given power level. Generally, the louder the sound is, the more power it consumes. So, the user should hear music at a regular volume to avoid battery stress. However, class D amplifiers operate by quickly switching the states of the output devices between on and off, spending less time in the linear operation mode. So, there is less energy lost as heat, as a class D amp uses less current to generate the same output power.

## Things to Keep in Mind for Better Car Audio

Before purchasing another battery for car audio, you should ensure your present alternator generates enough power for your car’s audio system. The alternator must be powerful enough to handle two batteries and the heavy-duty audio. Suppose your alternator cannot produce enough power to charge the current battery and to power the amplifier. Then, adding another battery will not do any good to your audio experience.

While purchasing a second battery for car audio, remember that both of your car’s batteries should be of the same family. The AGM battery usually has a higher resting voltage than the traditional one. So, pairing a standard flooded lead-acid battery with an AGM battery can drain out each other.

When connected, the lead-acid battery cannot match the AGM’s higher voltage without any external current. The AGM battery drains out to match the lead-acid battery’s voltage. It is a sluggish process, but it drastically damages both batteries.

After adding an extra battery, the secondary one can drain out the primary one if there’s no isolator in place. So, you should also add an isolator while adding an extra battery to prevent this battery from draining.

It is particularly useful since the isolator allows both batteries to charge even while the vehicle is running. The isolator also isolates both batteries when the car is off to ensure that excessive usage doesn’t lead to the depletion of the primary battery.

`Read Also: Different Ways of Fixing Car Stereo Draining Battery`

## Final Words

There are several things like battery size, car health, expense, and maintenance to consider before purchasing an extra battery for car audio. Even though it is a hectic process, if done properly, it can significantly improve your car’s performance.

You should first identify the cause of your car’s underperformance. Then, you should explore if there are any other less expensive ways to resolve your audio issue. Only when the battery performance is the root cause you should opt for an extra battery. While purchasing the battery, don’t forget to pick the right size with the right configuration that suits your car’s composition.