Power problems! how to get more?

Welp - I have a nice system in my Cavalier 2001, but I'm pretty sure I'm not getting enough electrical power.

I have a smaller battery than stock (because it was cheaper when I needed to replace it)

And a stock alternator........

So my options are
1. Replace stock with a Optima batt
2. New Alternator
3. New stock, and 2nd Battery
Or all of the above.

So I am being a basshead :) but, I love it, I figured someone out there might know a good option to fix it.


I think I got the straight answers I needed

First - upgrade the magic three
(wires going to the alternator, ground, battery)
Then - Battery - Optima Yellow Top
Then - 160 Amp Alternator

Damn it, gonna cost a few bucks, hopefully I can find it somewhat used, so I can sell it back on e-bay and lose only a little bit.

Most car audio guys swear by them, but I also heard the battery doesn't matter when your car is running, its the alternator that counts.

A high output alternator is going to cost you a lot of money. I would try this first...

1. Replace the voltage regulator on your stock alternator

2. Purchasing a rebuilt stock alternator (with new regulator)

3. Trying to find a larger OEM GM alternator that is direct bolt on for your car and purchase a rebuilt one.

Also a capacitor can help.

I do have a 2 Farad Cap....most people tell me its only a band-aid and doesn't really help if you aren't powering the system amps needed.

It takes some of the stress off the battery, basically a cap is meant to discharge quicker and refill quicker than a battery or "cycle". A cap stores energey and acts as a buffer between the battery and the amps. I think that with your set-up you would be happy with a proper battery(optima is good), the cap you have and then go with the upgrade path I listed before. Keep in mind that your stock alternator may not be putting out close to the juice that it did when it was new. Also you say you that you 'think' your not getting enough juice...get you the voltmeter and measure it will the system plays. Every upgrade you do should help it stabilize a little better, until there is virtually no voltage drop on the big bass hits.


Actually got out the DMM today on it

When the bass hits, it varies from 10.5-11 Volts

Steady 14 Volts otherwise.

10.5-11 is baaaaaaad but you know that you have an undersized battery, so start there. Optima or similair drycell will make a big difference.

Okay - I got more info

Even most regulated power supplies for amps STILL drop wattage when the voltage drops, this is where JL is very good (it stays constant from 11v-15v)


Zayex, good wiring will optimize the ability of your system to get all the power you can supply, but Fin's running a slightly undersized battery and close to 1500 watts rms last I checked. With convential amps you get about 50% efficency so draw be up to 3000watts....meaning that at max volume he could have power consumption spiking up to 200amps...a lot more than any standard charging system can handle.

Fin, if your thinking about upgrading your amp, JL is nice, BUT you don't want your voltage to drop like that, it's bads for everything electrical in your car. What you want is a digital bass amp that consumes less amperage to begin with, not a JL that can has an overbuilt power supply that is regulated down to a max wattage and can keep that at low volts ( I can explain that better if it's unclear)

Check out these guys


I ran their 700D with two top of line 12" pioneer subs and about 300 watts RMS for my inside speakers. My car had a Orbital Gel Cell Battery, 4 gauge wire, no cap and an old alternator (110A with 130k on it). My power would dip to no less 13.0 volts on max hits and the bass was so strong that I couldn't drive (it made you disoreinted and dizzy) with a cap I would have been fine, but I was just running it for a few weeks cause the local MMATS rep was trying to get us to carry their line.

Sorry White, work was getting the way of my posting again...

Forget what I said, I'll be more to the point...

If the JL can make 500 watts at 11 volts it producing 45 amps of power, so techinically it could make 680 watts at 15 volts with the same amperage... But the it's regulated to only make that 500 rms (that's what I meant by regulated to a max wattage) Now if oyu run it at 15 volts, it will only need to produce 33 amps to make that same power (In this amps case voltage and amperage will change but watts will remain the same)

You also have to keep in mind that a typical amp is only 50% efficient, meaning that for 1500 watts rms, the amp is consuming 3000 watts of power or 4200 watts in spikes (typical power consumption is going to be below RMS power even in spikes) at 12 volts a 4200 watt spike could drain 350amps...way more than the stock charging the system in a cavalier can handle... can handle. This kind of power drain will hurt a conventional battery, that's why you should use a deep cycle battery, as it's meant to stand up to this kind of abuse. Also a deep cycle battery will generally offer much more CCA than a lead-acid of the same size.

Now back to the JL amp...it may be able to produce it's power at 11 volts, BUT you don't want your car running down there. Lights will still dim, ignition systems will be underpowered etc... A better solution is to make the power more effeincenty, by going to a class D sub amp. MMATS amps run at 90% effiency meaning you will draw only slightly more than half of the amperage that a convential amp will draw.

I thought deep cycle was reserved for dry cell, but I guess it's too seperate things, what I should have said was that dry-cell will provide more CCA per size than lead acids...

The deep cycling comes into playing with the surging...the cap(s) will handle the surges, but the battery will still get drained severely by them.

From before...

"This kind of power drain will hurt a conventional battery, that's why you should use a deep cycle battery, as it's meant to stand up to this kind of abuse."

Zayex, I agree with about the wiring, in fact no matter what you upgrade it's worthless unless your wiring is solid. I don't like going over 4 gauge wire in a car cause it gets difficult to run the wire and hide it well. If you need more than a single 4G I recommend doubling it which will give you an effective 1 gauge wire (doubling drops by 3 i.e. to 8 would be a 5 etc.)

You are a little off in terms of your formulas, Current X Volts = Amp, but interms of convential automobile amplifiers, you need to multiply by your effiency to get your output or divide the output by the effiency to get the consumption. In Fin's case he was running 1500 watts rms. Now if you want max draw, y you should take the max power, which is more like 2100 watts. Divide that by 50% effeceincy and you get 4200 watts at 12 volts you get 350 amps.

A conventional starter can draw that, but it's fleeting. Think of every crank of the starter being a comparable pulse to a bass hit. If your car cranks more than 3 or 4 times it probably has problem. If your bass hits hard 100 times in a 3 minute song that's pretty normal. It's the continual draw of power that depletes the battery.

The best way to get around this is to consume less power and go with a Digital amp. I would do that long before I went to replace an alternator.

Not that Fin's even here anymore, but here's the consensus...

1. Upgrade the magic three as you said...

2. Are you running at least a single 4 GA to the rear? Also make sure your ground in the back is very good.

3. Go with the optima, more CCA for it's size than a lead acid. Can recover better even if do deplete it with your booty rhymes.

4. Replace the voltage regulator in your alternator.

5. If you are still having problems, ditch your sub amp and go with a digital one. For 1000 watts rms at 12 votls you will draw an average of 92 amps at full power vs 167 amps for conventional amp.