How many amps does my alternator need to run a 2000 watt amp?

I am getting a 2000 watt boss amp and I don t know if my stock alternator has enough amperage to run this amp. What is recommended for this size amp. And would it be better to use a audio voltage capacitor for this setup

Other answer:

The Boss R2000M is fused at 60 amps (2 x 30 amp fuses) so that's the most it can draw without blowing a fuse. In normal usage it probably doesn't draw more than 30 or 40 at high volume. A typical vehicle draws about 40-50 amps at night with lights, blower, radio, wipers and other electrical equipment on, but some draw more and some less.

So lets say the total load is around 80 amps between the two. Common wisdom says that the alternator should be capable of producing at least 50% more power than needed so an alternator rated 120 amps would be the minimum, but you can probably get away 90 or 100 if you don't drive a lot at night or play the music too loud. However, so that it runs cooler and has the longest life, and so you can be reasonably certain of no issues like flickering headlights, a load rating at least twice the max possible demand is what most auto manufacturers would install, so 150-200 amps would be a good idea. You can't have too high of a rating because an alternator will only supply what is demanded from it.

By the way, your supposed "2000 watt" Boss amp doesn't come anywhere near that figure except possibly in transients measured in thousandths of a second, quicker than you can blink. 60 amps (fuse rating) times 14 volts alternator voltage = 840 watts peak. The average output would be around 420 watts rms. You cannot ever trust the advertising of cheap amplifier manufacturers, and Boss is about as bottom-of-the-barrel as it gets. For that amp I wouldn't recommend a sub rated at more than 600 watts RMS.

Last thing, capacitors are more or less a useless gimmick. Read why:

don r:
You need just 167amps for the 2000 watts entertainment, but wait; Does that Boss amp really give 2000 RMS watts? Read the specs again. At any rate, the rest of the car needs power from the alternator too. When your license plate is flapping, the trunk lid is rippling and rattling like ocean surf and the mirrors are jumping up and down, I hope that makes you happy. Capacitors are a waste of money and cannot increase available power. 400 watts is enough to hurt you, so how much of the 2000 watts do you think you need to use?
390A for true 2000W amp, but for your setup, 165A. I would get one that outputs more, because you'll likely want to upgrade your sound system at some point.

Watt / Volt = Amp

So for a true 2000 watts: 166.67A

2000W / 12V = 166.67A (rounded to 100th)

Your Boss amp, however, will probably only output 1000 watts RMS at best (if you're lucky). It will more likely output a max RMS of 500 watts or less. So:

1000W / 12V = 83.33A

500W / 12V = 41.67A

Also, remember that amps are not 100% efficient, so if you have a class D amp, you will want to add maybe 20% on top of that. So:

2000W RMS – Up to 200A
1000W RMS – Up to 100A
500W RMS – Up to 50A

Your amp most likely outputs a max of 500W RMS, so at most it will be using around 50A.

A stock vehicle, on average, will draw around 60A at night with lights and the blower on. 50A + 60A = 110A. Plus, you will want an alternator that can output at least 50% more than the total amount of amps being drawn. That would be around 165A.

Unless you drive a 1988 Tercel, or something similar — you re fine. Even if you DO drive a 1988 Tercel, you re probably fine.

Boss, like many cheap brands promotes peak/max power which is a meaningless spec. And their RMS ratings, which SHOULD tell you what the amp is actually capable of, are lies too.
That amp will do 400-500w rms at minimum impedance.
day-to-day moderate volume playing music you're looking at 15-20A or so.

The Big Guy:
a 2000 watt boss amp probably only produces 400 watts RMS, your fine. Stock works.
Steve S:
How big is the supply cable going to the amp? 2000/13.2 closer to 150 amps from other big amps Ive played with Ill guess around 50 to 70 amps
I think something like 200A. I dont know how you make this.

I'd recommend the Mechman H/O alt.

They are made in the US.

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