Lights dim when bass hits, weird.

**HyperZulu** · 07-18-2007, 10:32 PM

The battery regulates the voltage supplied to the system. Anyway, you can rule out the alternator simply by playing the system with the engine turned off. If the problem happens with the engine off, then it's not the alternator.

It has to be the battery. But honestly, with a computer in the mix, you have to remember that it doesn't draw power from the electrical system like amps do. Amps draw power harmonically, but computers draw power pretty steadily, putting a more constant draw on the electrical components. So, it could have been draining your battery pretty badly where your alternator couldn't keep up. How much power does your computer draw?

To give you an idea of what's going on, I have my computer drawing something like 180-200w and I have an Optima Yellow Top with a 180A alternator and normally with the engine running I have about 14v generated... with the whole system running and A/C full blast, it drops to 12.75v sometimes. Pretty heavy load and all I have is the computer, a 600w and 200w amp.

**jim_barnesly** · 07-19-2007, 03:12 AM

This is the problem they invented high capacity capacitors for. Your amp is drawing too much current, causing the voltage over the total load to drop, therefore dim lights. Use a 1 farad (or higher depending on how bad the problem is) capacitor, that way, when the amp draws alot of current, it will take it from the capacitor reserve and not the battery.

**ironfinger** · 07-19-2007, 03:23 AM

Originally Posted by HyperZulu

To give you an idea of what's going on, I have my computer drawing something like 180-200w and I have an Optima Yellow Top with a 180A alternator and normally with the engine running I have about 14v generated... with the whole system running and A/C full blast, it drops to 12.75v sometimes. Pretty heavy load and all I have is the computer, a 600w and 200w amp.

that's craziness. I got a carputer, sound processor, and 3 amps(~1300rms) running off a duralast battery and stock 90 amp alternator. My only explanation for no music dimming is a big3 upgrade and mostly D powered amps. I haven't really been monitoring voltage since I don't have a meter hooked up. Do you think there's anything I should be worried about?

**durwood** · 07-19-2007, 07:58 AM

ironfinger you are fine.

I'm not going to get into a debate about whether or not caps work. It has been discussed many times. Plus in case no one saw it he has one already (and it doesn't seem to be doing anything)

To the opt, when you get the problem resolved please post what fixes it so that others that might come across this thread might help them out. Again I recommend that you get your battery tested and make sure all your connections are tight. Also clean any corrosion off on any critical connections.

**monkeyracer** · 07-19-2007, 10:14 AM

ooh, forgot about corrosion. That's a good thing to check, It can greatly reduce the current allowed through that connection...

**malkamus** · 07-19-2007, 02:20 PM

If you have a cap, and your battery is good, then you need an oversized alt. There is no other way around it. A battery stores, it does nothing else. A cap stores, it too does nothing else. If your lights dim with both of the storage devices then you need something that creates more power, that is the alternator and regulator. Check your parts store, see if an oversized alt is available. Many cars had a few choices depending on the factory electrical options. If none are available or you already have the largest, then you will have to have yours wound. Most alternator shops will do it for around 2.00 an amp. I took my 120 amp in and had a 200 amp winding in it.

**HyperZulu** · 07-19-2007, 03:11 PM

Nothing to be worried about. Your system may not get as much power as it could use at worst... I imagine if your alternator would have lasted 120k miles without a heavy load, it will die out sooner. Alternators are usually pretty solid components.

I bought the alt and battery not out of necessity...

Originally Posted by ironfinger

that's craziness. I got a carputer, sound processor, and 3 amps(~1300rms) running off a duralast battery and stock 90 amp alternator. My only explanation for no music dimming is a big3 upgrade and mostly D powered amps. I haven't really been monitoring voltage since I don't have a meter hooked up. Do you think there's anything I should be worried about?

**Dillusion** · 07-19-2007, 08:58 PM

I had the battery tested at autozone and its 'fine'.

I've also tried a new headunit, same result.

I will try removing the amp frm the system and test that theory.

**TheLlama** · 07-21-2007, 02:20 PM

Originally Posted by HyperZulu

The battery regulates the voltage supplied to the system.

Please explain.

**pancit175** · 07-21-2007, 09:03 PM

Originally Posted by HyperZulu

The battery regulates the voltage supplied to the system.

Originally Posted by TheLlama

Please explain.

The battery, while the engine is running, it is acting as an efficient capacitor. I wish I had the chance to get a picture or draw out what i'm talking about but I'll try to explain.
Long and short of it, you may already know this, but within the altenator, before it runs through the diodes, it is an AC voltage generator. And in simplest terms the negative portion of the AC voltage is reversed into a positive voltage. But because of this, the voltage is "dirty" with peaks and dips in the signal (kind of like: ^^^^^) And you may know that a capacitor is used to clean up this signal as a capacitor is resistant to change in voltage.