High-performance car audio systems often require a lot of juice, and the original electrical system in some cars simply isn’t up to the task. The solution in some cases is to install a high-output alternator, but that only works when the engine is running. If you want more power when the engine is off, the best option is to install a second battery.

If you want to add some extra juice to your audio equipment, you have two basic options. The first option is to replace your original equipment manufacturer (OEM) battery with the largest, highest capacity battery that will fit in the available space. This is the easiest solution and is usually good enough for most situations.

The other option is to replace your single battery with brand new batteries or add a deep cycle backup. This is more complicated, but it can potentially give you even more reserve amps and has the added benefit of allowing you to install the second battery close to your amp.

Of course, it’s also important to remember that there are situations where a reinforcement cap or a high-output alternator are a better idea than an extra battery. Adding a second battery is a good idea if you want to keep your car audio system running longer when the engine is off, but it won’t help you when the engine is actually running.