Car Audio 101 - Alternator Tutorial

DIY with Mike Stiers
http://www.maxxsonics.com

Back to Basics -- Car Audio 101
By Mike Stiers
So you've decided to upgrade your car stereo system? A great deal of research and planning should go into this purchase since there is a lot to consider. Do you desire a nice upgrade of your factory speakers, are you looking for a Sound Quality overall of speakers, subwoofers and amplifiers, or are you designing a vision-blurring SPL machine? It is important to make a list of exactly what you are looking to replace or add to your audio system so that you can prepare your electrical system for the investment to come.

Many people do not realize that their vehicles' factory electrical system was not designed for aftermarket audio equipment. In fact, most factory electrical systems can only handle an audio system of 600 to 1200 watts. The lower end of the scale being the smaller vehicles and most foreign rides, and the upper end being large trucks and sport utility vehicles. As you increase demand, you need to look at upgrading your battery, alternator and most importantly your "Big 3."

ALTERNATORS

The alternator powers the vehicle, all components and recharges the battery. A standard factory alternator ranges from 40 amps to 120 amps depending on vehicle. When the alternator is under high demand or the demand exceeds the alternators capability, your voltage will begin to fall and rely on the reserve of the battery. Lets use a 65 amp alternator for example in determining what aftermarket audio equipment the alternator can sufficiently power. In perfect condition, your 65 amp factory alternator is charging at 14.4 volts and is capable of supplying 936 watts. (65A x 14.4V = 936 watts) Your vehicle requires 30%-50% of this to run and operate standard vehicle components. If we use the middle, 40%, you are left with approximately 561 watts for your aftermarket audio equipment. (936W x (100% - 40%) = 561W) This 561watts is based on a 100% efficient amplifier which we know is not realistic. Lets assume you choose an 80% efficient amplifier, which is very efficient. If this amplifier uses 561watts and is 80% efficient, it will produce 448.8 watts for your speakers or subwoofers. (561W x (.8) = 448.8 watts) Going beyond this point and you begin to tap into the reserve of the battery. The result is a decrease in amplifier efficiency and an increase in heat due to decreases in voltage and increases in amperage. This is very hard on the alternator and amplifiers in the system. By now Im sure you see why an upgraded alternator is vital when upgrading your audio system.

DETERMINING POTENTIAL OF CURRENT ALTERNATOR:
Step 1:
Alternator Amperage Rating x 14.4V = Potential Wattage
A x 14.4V = W

Step 2:
Potential Wattage x (Maximum Potential Percentage Used to Run Vehicle) = Watts Available for Aftermarket Audio System
Answer from Step 1 x (100% - 40%) = Watts for Aftermarket Amplifier(s)

Step 3:
Answer from Step 2 (100% Efficient Amp) x (Actual Efficiency of Amplifier) = Watts that can be produced in current application

Big 3 Upgrade

XS Power Alternators
http://www.4xspower.com

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[twin0matic]

Hey audio newb here, im gonna be buying about 7000watts worth of speakers powered by a 5000w 2chanel at 2 ohms (2500w each channel) amp and a 1400 watt amp (4 channel), i was wondering if getting a new alternator is an absolute have to (being on a tight budget). i would only be playing it on its mid-low to lowest volumes 99% of the time, and would only blast it on its max for maby 15-60 secounds at a time for demos up to once a day depending which friends wana hear it.

[MaxxsonicsUSAInc]

@twin0matic If you are purchasing a 5kw rms amplifier, then you better be prepared to upgrade your alternator and add additional batteries. Otherwise, your 5kw amp will quickly be damaged.

[MikeAndTaya]

Adding a capacitor to the system should take some strain off the stock alternator and upgraded battery though, right? I have a 4000w peak amp (supposedly, I'm growing suspicious b/c it came w/ two 40amp fuses built-in) 2 channels, 20 farad cap, it hits pretty hard but I want to make sure I'm getting the most power possible. I haven't done the big 3 yet, but that'll probably be my next step.

[MaxxsonicsUSAInc]

@MikeAndTaya Capacitors are temporary storage devices. Standing alone they have no voltage or current. If your electrical system can't keep up with the demand of your audio system then a cap will simply cause additional strain as it is resistance between your alt/batt and amplifier. Caps are great once you have already upgraded your electrical system. Your amp must be marketed as 4kw max. Two 40amp fuses tell me the amp is capable of 800-1100watts.

[Fellopian22]

How do i find out how many amps my alternator is producing?

[MaxxsonicsUSAInc]

@Fellopian22 Stop by an AutoZone store or similar. Ask them if they can test your alternator. In most cases, they will be happy to wheel their little test cart out to your car and measure the alt and batt for you.

[fingerboy18]

@MaxxsonicsUSAInc Thank you. Like I said, a great video!

[MaxxsonicsUSAInc]

@michaelmorr11 You should be in good shape with a simple deep cycle battery upgrade. Have you experienced much dimming of your headlights?

[MaxxsonicsUSAInc]

@CKAYY187 What is the rms power rating of your amplifier? Do you have dimming lights?

[MaxxsonicsUSAInc]

@jose01ification What is the rms power rating of your amplifier? Do you have dimming lights?

[MaxxsonicsUSAInc]

@xgac16x In most cases, a 175-200amp alt with a decent battery for reserve will do the trick. BUT, you will want to contact an alternator manufacturer with the make, model and year of your vehicle to determine the size of your factory alt and what models are available as upgrades.

[MaxxsonicsUSAInc]

@fingerboy18 *Thumbs UP* Well said.

[fingerboy18]

Great video. Although, assuming worst case scenarios is the smartest method. Account for measured power cable resistance, lowest feasible voltage across the battery, worst possible amplifier efficiency, and peak current draw to ensure a safely operating system.