Recapping Why you Need a High Amperage Output Alternator

In the last blog post, Capacitors: 5 Fast Facts You Need to Know, I briefly touched on upgrading the Alternator. Many DIYers think that adding additional batteries is the best solution for providing power for their new sound systems. In reality, the amount of batteries won’t matter if they are not receiving enough power from the alternator. Additional batteries or capacitors are simply delaying the inevitable.

A typical factory alternator will output 80-90 amps. Regardless of how many batteries or capacitors you use, you have to be sure that the alternator will be able to handle your new car audio system.

This Example from our article Car Audio Capacitors Vs. Power Cells explains this perfectly:

“I’m going to use the example of a 1000W RMS system. Certain factors, such as heat and board configuration, prevent amplifiers from operating at 100% efficiency. Let’s say that our amp is 70% efficient (note: the best amps are about 80% efficient). To achieve 1000 watts continuous, we really want to achieve 1000W/.70= 1428.57 peak wattage. Wattage divided by voltage gives us the amp rating we will need. 14.4V represents the peak voltage of your standard dry-cell battery so, 1428.57W/14.4V=99.21A. We can say, to produce 1000W of continuous power, the vehicle will have to supply the aftermarket amplifiers with 99.21A of power…

First, check the size of your current alternator. Usually, 30-40% of the amperage of your alternator is used to power the electronics (power windows, cabin lights) in your vehicle. If your vehicle has an 80-amp alternator, and 35% of the alternators output is being used by the electronics in your car, that would leave 65% for aftermarket accessories or, 80 x .65 = 52 amps for your system.”

What Amperage Output Do I Need?

According to this example, the factory alternator could only handle 52 amps. The alternator would obviously need to be upgraded immediately. 240 amps is one of the most common outputs for high amperage output alternators. An output like this would be much better suited for that 1000W RMS system.

This allows your new alternator to produce more than enough power for a system of that quality. Dimming lights and dead batteries would be a thing of the past in this scenario.

240-amp output alternators would give you plenty of options for most vehicles as well. Obviously, the actual output you need for your system completely depends on how powerful your amplifier is; however, A high output alternator needs to be one of your first considerations when purchasing a new sound system.