how to determine amp power drain

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Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=115354
Printed Date: May 08, 2024 at 6:00 PM

Topic: how to determine amp power drain

Posted By: jdalphin
Subject: how to determine amp power drain
Date Posted: July 29, 2009 at 5:13 PM

I am stuck between either a Power Acoustik BAMF-2000/1D amp (2000W peak) and a Power Acoustik BAMF-4000/1D amp (4000W peak). Deciding between the two all depends on what subs I want to get, but that's for a different topic. My car has a 95 amp alternator, and I'm trying to determine the power draw of those two amps. Is there a formula to figuring out their power draw?

Replies:

Posted By: ianarian
Date Posted: July 29, 2009 at 7:11 PM

P/E=I or 4000 watts/14.4 volts= your alternator size...
ball park estimates a potential

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This is what I do for FUN!

Posted By: jdalphin
Date Posted: July 29, 2009 at 11:34 PM

So I'd be looking at getting a bigger alternator, for either of those two amps. Am I right?

Posted By: whiterob
Date Posted: July 30, 2009 at 1:17 AM

jdalphin wrote:

So I'd be looking at getting a bigger alternator, for either of those two amps. Am I right?

Well first, don't look at any "peak" or "max" power ratings. They mean nothing and are only used for marketing.

Assuming that the first amp is about 1000w RMS then you can get away using a stock alternator. The second amp would definetly need a high output alternator to run fully.

I use the calculation below...

1000 watts / 14.4 volts (running voltage of car) = 70A.
70A / 0.8 (80% efficient amp aka class D) = 87A
So you need 87A to fully power your amp. Now considering that you typically run much less then full power when the sub is going your current draw will be less.

So you would could run the first amp off of the stock alternator but upgrading the alternator would be a good idea. Also, do the big 3 upgrade. More info is found in the "hot topics" section.

Posted By: jdalphin
Date Posted: July 30, 2009 at 1:20 AM

whiterob wrote:

jdalphin wrote:

So I'd be looking at getting a bigger alternator, for either of those two amps. Am I right?

Well first, don't look at any "peak" or "max" power ratings. They mean nothing and are only used for marketing.

Assuming that the first amp is about 1000w RMS then you can get away using a stock alternator. The second amp would definetly need a high output alternator to run fully.

I use the calculation below...

1000 watts / 14.4 volts (running voltage of car) = 70A.
70A / 0.8 (80% efficient amp aka class D) = 87A
So you need 87A to fully power your amp. Now considering that you typically run much less then full power when the sub is going your current draw will be less.

So you would could run the first amp off of the stock alternator but upgrading the alternator would be a good idea. Also, do the big 3 upgrade. More info is found in the "hot topics" section.

The BAMF-2000/1D amp is 1200 Watts RMS at 1 ohm. 103.75 a is what your formula came out to be. Lets see, I think a 220 amp from iraggi isn't out of the question...maybe out of the budget...but not out of the question.

Posted By: spmpdr
Date Posted: July 30, 2009 at 7:00 AM

Do the big 3 upgrade and see how that works.I bet youll be just fine

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-A vision without a plan is just a hallucination-

Posted By: jdalphin
Date Posted: July 31, 2009 at 1:07 AM

So...if I have read correctly, replace the 3 main cables in my car, and I should be fine with that stock alternator? Correct me if I'm wrong, but wouldn't that 2000W amp easily eat up all the output from it? 104a at it's RMS value and 173a at it's peak.

Posted By: jdalphin
Date Posted: August 05, 2009 at 1:38 PM

Anyone know what happened to Iraggi? Last time I was on ebay, I couldn't find their store.