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Thread: Help with figuring out amp draw |
    
Silver Member Username: Sony224422
Deep River,
CT
US
Post Number: 125
Registered: Dec-04
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| Posted on Tuesday, March 29, 2005 - 01:03 am: |
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I have two amps now in my car. ones 250 watt peak.. and the other is a MTX Thunder801d so its 800 RMS. How many amps is this drawing from the alternator. I'm not sure what the MTX peaks at.. but any help would be helpful. Thanks |
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Silver Member Username: Fishy
Tamarac Ft.Laud,
FL
USA
Post Number: 791
Registered: Sep-04
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| Posted on Tuesday, March 29, 2005 - 02:16 am: |
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If you add up the fuses on both amps thats the MOST they could ever draw. Under normal listening conditions they probably draw a good deal less.
-Fishy |
Gold Member Username: James1115
Wilton,
Ct
Post Number: 2049
Registered: Dec-04
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| Posted on Tuesday, March 29, 2005 - 02:34 am: |
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I would say 80-90amps at peak listening levels. Typically you take the number of RMS watts and divide by 12 to get amps. |
Silver Member Username: Sony224422
Deep River,
CT
US
Post Number: 126
Registered: Dec-04
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| Posted on Tuesday, March 29, 2005 - 03:50 pm: |
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so how does that work with the alternator.. say i have a 120 amp alternator.. i would need a bigger one to power all of these |
Gold Member Username: Carguy
Post Number: 2116
Registered: Nov-04
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| Posted on Tuesday, March 29, 2005 - 04:13 pm: |
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Depending on your car, stock electronics and electical components could eat up anywhere from 40A - 70A of the alternator's power. So whatever is left over, will be available for the amps.
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Silver Member Username: Jwbulger79
Florida
Post Number: 352
Registered: Nov-04
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| Posted on Tuesday, March 29, 2005 - 04:21 pm: |
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eric, once you figure out the current draw of your audio system, for example 1000watts RMS divided by 12 = 83 amps, add that to what your vehicle needs, which is usually 60 to 80% of the stock alternator's rating. so, if your stock alt is 120A, your vehicle probably needs 70-90A with the lights, a/c, etc on.
the audio system in this example would also need 83A, so add those up and at full crank with lights and a/c on, you would need your alt to put out 153 to 183 amps. in which case you would be more than fine to get a 200A alternator.
as fishy mentioned, normal listening conditions will require much less power due to...
"Every time you double the audible volume of your stereo system, you're using ten times the power to get there.
Now look at that in the other direction, starting with an amp putting out 100 watts total RMS power at full output.
At half volume from peak (audibly, to your ears) you're now using 10 watts of power.
Halve that volume again, to a quarter of full volume (still usually very loud) and now your 100 watt amplifier is putting out about 1 watt of power not accounting for efficiency losses due to power supply." -KikiTheCat aka Glasswolf from www.CarAudioCentral.net |
Gold Member Username: Carguy
Post Number: 2119
Registered: Nov-04
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| Posted on Tuesday, March 29, 2005 - 04:25 pm: |
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KikiTheCat is glasswolf? How K.i.n.k.y. |
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