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good evening to all! I have a 93 acura legend. My voltage keeps dropping headlights dim i know something gotta be wrong just cant get to the bottom of it. I'm running sky-high 0gauge ofc, I have two fi audio xv3 12s a kicker cxa 1800 and stock battery and 250 singer alt. I've killed one battery im on my next battery. I have future plans on getting a xs agm but I keep reading that I should be good with just the high output alt. Hope you guys can help me out if you will. 

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Could be a bad ground/ grounds. Make sure all are clean bare metal and as tight as you can possibly get them. Also, make sure they're as short as possible... no more than 18 inches is a good rule of thumb, but the shorter the better. Also, if you haven't done the big 3 upgrade, do that as soon as you can

2011 Chevy Silverado under construction

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also check gain if its too high clipping will increase power draw that isn't needed in the first place

skar sk2500.1
0 gauge power and ground kunukonceptz
alpine HU
vxi65 components on BA gt-275
new build log -> http://www.stevemeadedesigns.com/board/topic/150642-project-d-kon-deathcards-build-log/#entry2148821
2 x-15 sundowns

singer alt, odyssey bat, and maxwell ultra caps

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My .02 worth...


This has all the tell tale signs of a failing voltage regulator or a bad ground.   


One very impromptu and rather inaccurate way to test for a failing regulator would be to drive the car for a while and turn on your headlights.   With the high beams on  the voltage at the battery should not dip below 14 volts.   This assumes the battery is capable of holding a charge.   Charge the battery overnight, start the car in the morning, and see what the voltage looks like right after starting versus after driving.   Keep the electrical load minimal as possible.    


Grounds:   Even with an old school cast iron engine I've found the best is a thick cable to the battery negative going to a 3/8" stud through the fender wall close to the battery.  From the stud there's one ground cable to the engine block, another to the alternator case and a third directly to the case of the starter.   There is a noticeable difference cranking the starter and battery charging voltage.      


Doing some rather rough engineering:   An 1800 Watt amp running full power assuming about 80 percent electrical efficiency would require 2,250 Watts.   At 12 volts this uses  187 Amperes of current.

Is a 250 A alternator "enough" ?    It all depends at what speed is the alternator producing 250 Amperes of current, how the car is being driven, and the total electrical load. 



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  • 4 weeks later...

Thank yall so much I know its been a while since I replied, but this problem is kinda sporadic. But one night I saw the light. For some reason its like my amp is grounding to the car chasis I kept seeing flashes coming from the rear so I just put some extra carpet down and problem is gone. I even get more sound from the subs as a result I've haven't really seen this before any feedback is always welcome and again thanks

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