the old battery i had used to jump all over the place when the bass from my stereo system hit hard and a little bit playing through without much bass (stereo system with 2 amps). my old battery however took a crap on me and i had to replace it with a new one. got the new one installed and noticed that my battery gauge doesnt bounce around at all, in fact, its sitting below zero. im not really one who studies up on electrical stuff, i try to avoid it at all costs. whats up with this?

 

See what happens when you tighten those connections!!

 

A good battery will take the power spikes with a lot less voltage drop, so you will see a lot less action on the ampmeter

 

If you are running high power amps and like a lot of bass you should add at least 1 1-farad capacitor to your electrical system. Your new battery is strong enough to handle most of the extra load from the audio system but when it ages you will start having the same problems that you had with the old battery. The capacitor is like an auxiliary battery that will supply extra power when you are playing bass-heavy music. Crutchfield sells big caps - I think they go up to 2 farads or so.



Rick B.

Bass player who uses a 625-watt per channel amp to drive 2 2x10 speakers. I know bass.

 

2 Farads is NOT a big cap.
http://www.woofersetc.com/index.cfm?...Product_ID=633

Anyway, for your setup, a good high power alternator is way better than even this 50 farad capacitor.

The last battery dies because the stereo was likely draining it faster than the alternator could charge it. Too many times up and down and batteries stop holding charges as the cells fail.

I'm guessing you have a stock alternator on your car.

If this is the case, I suggest...highly recommend, you upgrade to a CS144. It's a very easy swap that you can do in less than an hour.

 

actually, i have a performance alternator 100amps. that good enough?

 

No, probably not. I would think with the system you described you would want just that at idle. Your current alt probably only gives you half that at idle which is when the damage is done.

A CS144 will have over 100 amps at idle, and give you close to 200 amps at RPM...based on the model of CS144 obviously.

 

Got to disagree with you a little here Matt, The old battery (don't know how old) was not holding the voltage up with the base spikes (heavy current surges) . The fact that it settled down on the amp meter with a new battery indicated the battery was faulty, not that the alternator was not able to keep it charged.
That 100 amp alternator should do you fine unless you idle a lot with the base cranking.
Test it by putting a volt meter on the battery terminals and run the base up with the engine idling, the voltage should not drop below 12.5 or so with an ocasional drop to 12 or a bit less with HEAVY base bumps. If it remains above 12 at idle that alternator is plenty strong. You will get some benefit from a 1 farad cap, maybe 2 if you run a lot of base.

 

I don't think it just settled...I think it stopped working. Zero is zero, so somewhere the gauge is missing something.

 

While I do agree that a high output alternator is a must for a high power system... an alternator will never do what a capacitor is capable of. Yes, it will help with the dimming lights, but the capacitor provides a "pool" of power for surges in current demand. When the bass hits, you dont want the amp pulling all the power straight from the battery and alternator, you are just putting excessive loads on both, and both will fail prematurely. A capacitor makes things much easier on your whole electronic system.

 

I used to be a huge supporter of Caps, and I spent a lot of time messing with them in various systems and testing when they helped and when they didn't. The cost of the ones that make a difference are the ones that cost as much as new batteries so a battery failing after three years is still a lot cheaper for the lifetime of the car.

I used a test truck, a Bronco, at the stereo shop when I went through all this. First we installed a huge watt stereo on the stock battery and charging system and documented the output of the alternator, battery voltage, and things like how much the amps were drawing and if the lights were dimming in the dash and the headlights.

First we installed a few different caps and nothing made a difference until we got up to around 10 farads.

Then, with the cap installed, we upgraded the battery, alternator, and the grounds from the battery to the engine and frame.

The battery voltage never dropped below 13V and the lights would not dim...ever. Then, as a final test, we removed the capacitor and there was no change.

The battery lasted five years from what I heard from the guy that owned the Bronco, so he bought another battery and all was good. Had the system called for a $300 capacitor, he still would have had to replace the battery a year or so later at worst, and still have to buy another one.

The debate about capacitors just goes on and on at car audio forums, but the general consensus is that the ones that actually help are costly and make using them not very practical.

 

Zero on the stock amp meter is not going to tell you much since 30amps is only about a quarter inch and the needle is damped. Is it dead on zero, needle a bit to the right?...very subjective.
Voltmeter will tell the tale.
Dios, is the thing working or what?