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Thread: Do I need a new alternator? |
    
New member Username: Chrysler300c
Post Number: 6
Registered: Jan-06
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| Posted on Saturday, January 21, 2006 - 01:14 am: |
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I am thinking of adding either 4 Alpine Type Rs or 2 Alpine Type Xs. Either way i was wondering if I need a new alternator. I currently have a 160-Amp Alternator. Also does it matter what kind of battery you have? |
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Silver Member Username: Fandim
Reno,
Nevada
United State...
Post Number: 593
Registered: Jun-05
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| Posted on Saturday, January 21, 2006 - 03:20 am: |
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The amplifier is what matters, not your subs.  Can power Both the R's, and X's with a pretty big range of power, so really you need to be more specific.
You can figure out how many amps you'll need, by taking the RMS wattage of your amplifiers, and dividing it by the voltage, (i.e. does the amp put out (X) amount of volts at 14.4 volts? 13.8? 12?) and that will give you the amperage you'll need. Remember, most vehicles use around 60% of the stock alternators amperage rating (roughly). So you'll need to figure that in, too.
Seth |
New member Username: Chrysler300c
Post Number: 7
Registered: Jan-06
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| Posted on Saturday, January 21, 2006 - 01:31 pm: |
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Thanks that really helps a lot!!! |
Silver Member Username: N2audio
Lawrence,
Ks
USA
Post Number: 348
Registered: Mar-04
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| Posted on Saturday, January 21, 2006 - 09:39 pm: |
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the maximum current draw of an amp is not even a ballpark estimate of the type of current you actually need. max current draw is measured using sine wave test tones - music requires, at most, 1/3 of that. |
Silver Member Username: Fandim
Reno,
Nevada
United State...
Post Number: 599
Registered: Jun-05
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| Posted on Saturday, January 21, 2006 - 09:47 pm: |
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Optidriven, that's why I said take the RMS wattage of the amplifiers. Not max. Also, amps for mids/highs, are pretty consistent in their current draw.
Also, your amps are playing more than one frequency at once, unlike with test tones. I would definatley use the RMS wattage of the amp to determine the type of electrical system you need. Alot of rap/hip hop songs have consistent bass, or intense bass that's closely spaced, putting almost a constant draw. |
Gold Member Username: Tdbdadrummer
Wellsburg,
WV
USA
Post Number: 1128
Registered: Aug-05
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| Posted on Saturday, January 21, 2006 - 10:47 pm: |
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You know if most vehicles use about 60%, and I have a stock 130A, that leaves me with...~52A free. Not bad I'd say...
If I upgraded to about 180A, I'd probably be set. |
Silver Member Username: N2audio
Lawrence,
Ks
USA
Post Number: 352
Registered: Mar-04
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| Posted on Saturday, January 21, 2006 - 11:28 pm: |
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it's called crest factor. Test tones draw a temendous amount of power vs. music.
For example - If an amp draws 100A and produces 1000w (maximum continuous RMS - much like any quality 1000w amp) on a test bench playing tones - it is doubtful there is any other material that could be considered music that would require more than 40 continuous amps at full volume.
When you factor in listening levels of less than full volume it's entirely possible a 1000w amp will draw 20-30A on average.
If you want to argue about this don't bother. Go to carsound.com. Search for duty cycle or crest factor. |
New member Username: Chrysler300c
Post Number: 8
Registered: Jan-06
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| Posted on Sunday, January 22, 2006 - 12:56 am: |
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Ok so I have a stock 160A and with an amp putting out 14 volts. According to the math im using about 143A which seems to be too much. Am i doing something wrong or do I definitely need a new alternator? |
Silver Member Username: N2audio
Lawrence,
Ks
USA
Post Number: 354
Registered: Mar-04
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| Posted on Monday, January 23, 2006 - 12:59 am: |
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what amps? |
Silver Member Username: Fandim
Reno,
Nevada
United State...
Post Number: 605
Registered: Jun-05
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| Posted on Monday, January 23, 2006 - 01:50 am: |
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say what you will, Opti. Class D amps are only 80% efficient, and pull an additional 20% of what they output (which is turned into heat), and class AB amps are even worse, and can pull almost double what the RMS value listed is.
I dont doubt you read what you claim on that website, not at all. And I'm sure it's true, but in real-world experience, I've found better to just have the power to feed your amps what they want, when they want it.
It dosnt take much to clip some subs to death (solobarics come to mind), and an amp with an inadequate supply of current will start clipping.
Seth |
