Should I eliminate the cap?

I have a 96 monte carlo LS with the stock alt. I have upgraded my wiring to 4awg "big 3"

Alt to battery

Neg. to Chasis

Chasis to Engine block.

I am running a Kenwood kdc-x889 HU with polk db components front and back( no amp)

Rockford Fosgate p500.2  hoocked up with 4awg wire and it is pushing  2 MA Audio dvc 4 ohm subs rated at 500 watts max each. I have the amp bridged to one channel.

Now in this set up I have a 1.0 farad cap( I bought it for really cheap, so I figured it would help me, I was very un-informed about caps then, now I know a little bit more), everytime my bass hits pretty hard at a moderate to high volume the lights will dimm, not buy much, but enough to bother me( I am anal about little things like that) I have replaced all of my interior lights to led's ( I do not know if this would make a difference in current draw or not, like less current than my regular inside bulbs). Should I just eliminate the cap? would I sacrifice power on my amp by eliminating it? would it make a difference in the sound of my bass? I am just really confused. Thats why I need your expert advice. Thank you.

Why not try and post the results?

PS read the grounding sticky at the top as Rockford amps need a darn good ground.

First, with the engine running, measure the voltage across the battery terminals.  Watch what happens with the music up a good bit.  Make a note.  Now do the same thing at the amp- measure voltage across the amp power and ground terminals.  How much of a difference do you notice?  Also, measure the resistance of your amp ground back to the negative battery terminal.

The purpose of a cap is to smooth out the voltage to the system- not to keep lights from dimming.  If you experience any significant dimming, you should have your alternator tested.

I checked the resistance of the ground of the amp to the battery neg with a multimeter and I got something like 0.02 ohms. Is this good or not?

geepherder do you want me to post the volt drop at the battery and at the amp? so you can give me a diagnost? I can do that right now and post again like in 15 min. let me know to go ahead and do it. Do I need to see the drop in the same bass not of the same song or can It just be any bass note?

I will go ahead and do that right now, but wouldn't be 12 volts at the amop all the time because of the cap? anyway i will go and post the results in about 15 min. thank you guys

Ok here we go

Amp volt drop was, without any sound through the woofers, 14.20 and with sound was anywhere in between 12.54 and 13.84 it kept changing so fast so I got the lowest volts and then the highest with a bass note.

Battery was 14.20 without any sound to woofers and the lowest it went was 13.06.

I did hear a wining noise in the alt at the time the bass was hitting, nopt very noticable but just a change on sound. ( I do not know much about alt's)

So what do you think? Is the cap helping me or should I just toss it?

Okay, the alt is still putting out above 13 volts at idle, sounds like it's okay.  The whining you describe- is it coming from the alternator itself?  Is it possibly coming from the belt?  If the belt is loose, you may hear some slipping- this will make the alternator work harder, and put undue wear on the belt.  If it's too tight, you may notice a squealing noise in the bearings.  This can lead to premature failure.

The cap is up to you.  I bet if you remove it, you notice a more significant light dimming.

As long as the alternator is able to supply the power needed, a cap is simply a filter to keep the voltage smooth.

Popeye, use one if you want to- it's all up to you- just realize it's purpose is not to power your amps, rather smooth out the system voltage.

Have it tested.  How long was it sitting?  Unless it was at least for several months, I don't think there would be a problem.

BTW, why are you using a gel cell battery- is this an extreme off-road vehicle or something?

popeye004 wrote:

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I see I had an optima gelcell battery but I left my truck in the cold with the battery in it (really stupid) and now it sometimes doesn't hold a charge can i fix this problem cause I feel bad throwing out a $250.00 battery. 

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