head lights and cap
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=100809
Printed Date: May 15, 2025 at 8:13 AM
Topic: head lights and cap
Posted By: absolutepower
Subject: head lights and cap
Date Posted: January 05, 2008 at 9:01 PM
i have a 1.5 farad cap runnin to my 400x2 ppi amp and my head lights still dimming. any advice?
Replies:
Posted By: audioman2007
Date Posted: January 05, 2008 at 9:09 PM
first off. Your cap is like a bettery. Its able to store voltage and gives it off it quick spurts when your amp needs it and gets charged back up in a split second. The only problem is that it also draws more from your alternator because now your alternator needs to charge your battery and the cap. Now depending on how you have your sub(s) wired will affect this. Obviously your amp will need more power for a 2 ohm load than a 4 ohm load. Your alternator might not be powerful enough.
Posted By: absolutepower
Date Posted: January 05, 2008 at 9:13 PM
so basically a stronger alternator is needed? i have 2 w6 10s runnin off the ppi . subs are in series
Posted By: audioman2007
Date Posted: January 05, 2008 at 9:17 PM
lights dim only at bass peaks? Also, is your cap digital?
Posted By: i am an idiot
Date Posted: January 05, 2008 at 9:22 PM
Does it matter if the cap is digital?
Posted By: audioman2007
Date Posted: January 05, 2008 at 9:40 PM
to check what your voltage is at with the music off and when bass hits. If your cap drops down pretty low, then your alternator isnt powerful enough
Posted By: absolutepower
Date Posted: January 06, 2008 at 12:33 AM
yes and yes
Posted By: absolutepower
Date Posted: January 06, 2008 at 12:53 AM
it drops almost a volt thats bout it
Posted By: aznboi3644
Date Posted: January 06, 2008 at 2:10 AM
if your voltage drops but then recovers quickly than I wouldn't worry.
as long as its above 12.5 volts it is fine
Posted By: sedate
Date Posted: January 06, 2008 at 8:06 AM
absolutepower wrote:
i have a 1.5 farad cap runnin to my 400x2 ppi amp and my head lights still dimming. any advice?
Have you wired your engine/battery with the Big 3? Are you using your stock battery? With a single amp like that, you do NOT need another alternator. Don't listen to anyone who tells you that. The cap probably isn't doing much either way. If the Big 3 doesn't end your lights issues, I recommend a deep cycle battery. ------------- "I'm finished!" - Daniel Plainview
Posted By: audioman2007
Date Posted: January 06, 2008 at 10:33 AM
Im sorry to say this but if your headlights dim with only having 1 amp, then you do have alternator problems. Your alternator is whats giving your amp the power it needs.
Posted By: KPierson
Date Posted: January 06, 2008 at 10:51 AM
What kind of car is it and how big is the alternator in it?
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Kevin Pierson
Posted By: audioman2007
Date Posted: January 06, 2008 at 11:12 AM
It also depends on how the subs are wired. If the amp is running at 2 ohms, ofcource then the amp needs more power from the alternator. I have a factory battery, factory alternator, factory ground cables. I run 3 amps. One for my subs, one for my speakers, and one for my tweeters. The only time my headlights dim is when the car is at idle, and my A/C or defroster is on.
Posted By: sedate
Date Posted: January 06, 2008 at 2:13 PM
audioman2007 wrote:
Im sorry to say this but if your headlights dim with only having 1 amp, then you do have alternator problems
Hmm. See, normally I might go along with this, except he's running a 440x2 ppi amplifier. I'm not 100% sure but if I recall those are class A/B channels, regardless, you can guesstimate ~1000 - ~1200 watt pulls off his stock charging system. So figure 80-amp spikes is on the conservative side of guesstimation here. If you think a stock charging system could handle these pulls without symptoms, then you have serious misunderstandings about the amount of power he's using here. I'm certainly not saying he needs a new alt. There is a huge chasm between 'new alternator' and 'lights still dim after cap' He's got a huge amplifier - not something that will totally overwhelm a charging system, but he's probably right about at the max of what a stock system can keep up with reasonably. He's not experiencing dead batteries (presumably), but he's got some pesky voltage symptoms. Reinforcing his engine wiring a deep cycle are the easiest ways to deal with this. He does NOT need a new alternator. That's a silly amount of money and time to throw at the problem. His power needs just aren't that extreme. ------------- "I'm finished!" - Daniel Plainview
Posted By: absolutepower
Date Posted: January 08, 2008 at 12:03 AM
08 carolla
Posted By: absolutepower
Date Posted: January 08, 2008 at 12:10 AM
so to answer all questions. first i dont know what the big 3 is. 2 i am running a stock battery in a 08 carolla. i have the 400x running briged to a to w610s wired in series. umm yes but when i frist got the cap the prob went away for a bit but now its back. so if some one can explain it in the eaisies way for me to under stand that would be highly appreciated. i am a installer but ive only been in the game for 3 months today. i have alot to learn and all advice and opions are well taken.
Posted By: jmelton86
Date Posted: January 08, 2008 at 12:38 AM
Do the Big3 upgrade; https://www.the12volt.com/installbay/forum_posts.asp~TID~73496~PN~1 Also, remove the capacitor. It's only hurting more. Your car came with a 80 or 90amp alternator from the factory. ------------- 2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001
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