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lights dim after upgradeing to ho alterna

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=112285
Printed Date: March 29, 2024 at 2:44 AM


Topic: lights dim after upgradeing to ho alterna

Posted By: shadowm891
Subject: lights dim after upgradeing to ho alterna
Date Posted: March 11, 2009 at 8:26 PM

hey guys how's it going im having a problem here i own a 2001 kia sportage with a 180 amp ho alternator running off a red top battery with 4 gauge wire as my big 3 upgrade. for some reasson when my car is siting in one spot and not moving my voltage will read 14v from battery off my voltage meeter but after i turn my system up it drops down from 14 to 12 volts. now for my system setup im running 2 12 inch kicker l5's off a cadence z7000 amp at 1 0hm with a clarion dxz465mp deck which is 1.8v preout and the gain on my amp is set to about 75%. now im post to be getting me a new deck in the mail which will have 4volt preouts do you think that would help my problem with the voltage some.



Replies:

Posted By: stang351w
Date Posted: March 11, 2009 at 8:45 PM

the deck wont make any real difference in the situation your talking about.  i'm not familiar with that amp but running at 1ohm it's safe to say your working that amp and it's drawing the power to show that.  how bad were the lights dimming befor you put the new alternator in? and what all did you do when you swapped the alt?  as for the voltage. that is pretty much normal. the car itself runs off of 12-13 volts while the charging system is up around 14 volt ( needs to be higher in order to charge) for example. if you have your car running you said you get 14 volts...shut the car off and you'll see the voltage drop back down to 13 volts (roughly)   but i would double check any and all connections you made while swapping the alt and doing the big 3 upgrade, make sure all the connections are clean and bare metal contact (just don't forget to paint or seal them up so they don't rust up)   most likely reason for the issue is your alternator is rated at the 180 amp output at a certain rpm (most alt's are around 2000 for peak output)  when your just sitting there not moving your car is idleing and the alt will put out less current then if you were driving.



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Tri County KustomZ
certified installer




Posted By: shadowm891
Date Posted: March 11, 2009 at 8:53 PM
i see well befor i did the alt upgrade i had a 70 amp alt so yeah if i were to turn it up all the way my car would die lol but now with the 180 amp alt driveing at night with lights on the dimming is not bad really its kind of like a little short flick




Posted By: shadowm891
Date Posted: March 11, 2009 at 9:10 PM
o yea forgot to ask this question the deck i have dose not have sub control on it so im useing the bass option on my deck as sub control not sure if that could be causeing the voltage drop or not.




Posted By: j.reed
Date Posted: March 11, 2009 at 11:17 PM
your alt may do a total output of 180 amps but what does it do at idle? 4 gauge to me for a big 3 is too small. 0 is what i would do but, 2 gauge for your situation would be fine. Since you are just getting a little flicker i would suggest just adding a small audio batt like a xstatic model 800 or an xstatice power pac(35 fared cap with a model 600 batt built in) both are pretty fast charging and would give you that extra bit to draw on while doing parking lot showing off. Also i wold upgrade you big 3 to at least 2 gauge.

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Posted By: shadowm891
Date Posted: March 12, 2009 at 6:23 AM
well here the site i went to to have my alternator built www.excessiveamperage.com. and from reading what the faq said the alternators he built start chargeing at idle. so im guessing that means total output but i'll send him a email today and see what he says. as for the big 3 upgrade yeah im starting to think 4 gauge is to small for what i got as well. the only reasson i did 4 was because i call 2 dif places asking if 4 gauge was ok to us with what i got and they said it should be fine. but i guess they were wrong there lol now for the flickering i get it when im driveing down the road at night.




Posted By: shadowm891
Date Posted: March 12, 2009 at 6:34 AM
well reading his website it has a question about when dose the alternator put out 14.6 volts and this what he said. It will put out full voltage as soon as the alternator cuts on and will remain around the same voltage throughout the RPM range




Posted By: soundnsecurity
Date Posted: March 12, 2009 at 8:46 AM
shadowm891 wrote:

well reading his website it has a question about when dose the alternator put out 14.6 volts and this what he said. It will put out full voltage as soon as the alternator cuts on and will remain around the same voltage throughout the RPM range


it will do 14.6 throughout all rpm's but thats voltage not current. at idle it is not giving you all of the 180 amps of current. maybe closer to 110 at idle.

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Posted By: ayalahomero
Date Posted: March 12, 2009 at 4:41 PM

I have an alternator from excessive amperage also.  My car idles very low, around 6-800 rpms.  The alt runs the 14.4 at the low rpm's but doesn't put out as much current as my stock alternator at idle.  Once you get up over 1000, or into the 1200 range it makes quite a bit of power.  And I believe puts out full 200a at 2000 rpm's.

You might give him a call and see if you got the overdrive pulley on your alternator.  This will help spin the alternator faster at the low rpm's.  Or if you have a way to adjust the idle on your car, maybe set it to idle at a little bit higher rpm's. 



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homero ayala




Posted By: shadowm891
Date Posted: March 12, 2009 at 6:16 PM
well fix my problem the bass drive on the amp was up so i turn it down and now with the car idle and lights on my system gets 13volts with system up my next step is to upgrade from 4 to 0 gauge on big upgrade and see if that jumps it to 14 volts




Posted By: bigjohnny
Date Posted: March 16, 2009 at 6:57 AM
I just leafed through this thread and wanted to add a couple of things.

Ive seen suggested that you need 70A of alternator power power 1000W of audio power... Not sure if its true, but my crappy math skills seem to think it sounds about right.

Secondly, how much amperage is your alternator putting out at idle speed? This is a spec that most companies overlook.
Idles speed output is rated at 2400 Alternator RPM. Figure out how big your main flywheel is, and how small your alternator pulley is, then do the math to figure out how fast your alt is turning when your car is at idle. (I dont know the math sorry... if someone else does id love to know)

Contact the company who makes your alt and ask them how many amps the alt is capable of producing at your measured idle speed.

I'd bet that at idle your alt can't produce a high enough output to power everything thats running.

One thing you could try is an "overdrive" pulley on your alt. Its just a smaller pulley so your alt will turn faster, thus putting out more amperage.




Posted By: shadowm891
Date Posted: March 17, 2009 at 6:21 AM
are they easy to replace these overdriver pulley's ?




Posted By: shadowm891
Date Posted: March 17, 2009 at 6:31 AM
yea i think i may need to get one i know the one i got on my alt not one since the size of it matches up with my stock alternator's pulley do u know where i can get me one for my alt





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