Why is my voltage still dropping?

I’m getting frustrated here. I used to run 4-gauge wire but upgraded to 1/0 OFC. Could the issue be that my amps are still using 4-gauge wire? My setup is 1/0 into a distribution block, then 4-gauge into my sub amp and speaker amp. Can someone explain how to stop the voltage drop?

What kind of car are you running this in?
How much power does your alternator put out?
Do you have a second battery installed?
What are the RMS wattages of your amps?

Cam said:
What kind of car are you running this in?
How much power does your alternator put out?
Do you have a second battery installed?
What are the RMS wattages of your amps?

I’ve got a 125-amp alternator. No second battery because I don’t want one over the gas tank. My sub amp is 1500 RMS, and the speaker amp is 600 RMS.

@Ash
How old is your main battery?

Cam said:
@Ash
How old is your main battery?

It’s new, but I think the last owner just went for the cheapest option. It’s a 50Ah battery, but I know I should have 100Ah for this setup. I’m just hesitant to spend $400 on a fancy alternator upgrade right now.

@Ash
Got it. Let me ask a few more things:

  • What gauge ground wire are you using?
  • Where is your ground point?
  • Did you make sure to sand down to bare metal for the ground?

When you say voltage drop, have you checked it with a multimeter? Or are you just going by dimming lights and your amp display?

@Cam
I’m using 4-gauge ground for both amps right now. I have 1/0 ground wire coming in tomorrow, hoping that helps.

@Cam
I’ve seen voltage as low as 10 on my amp’s display, but it usually stays between 12 and 13 when the drop happens.

@Cam
Yes, the lights inside the car dim, and I’m guessing the outside ones do too. It happens no matter where I’m driving.

Ash said:
@Cam
Yes, the lights inside the car dim, and I’m guessing the outside ones do too. It happens no matter where I’m driving.

Thanks for sticking with me here. A lot of things can cause voltage drops and dimming lights.

First, when your 1/0 ground wire arrives, make sure to ground it properly. Ideally, all your grounds should go to a single point. If your current ground point is on a wheel well or higher up, move it to the body floor—it’ll reduce resistance.

Use a multimeter to test every connection from the battery to your amps. Check voltage at each point, and if you find a bad connection, fix it. Do the same on the ground side, and make sure there’s no voltage there.

You’ll always see some voltage drop when the bass hits, but if it’s staying above 12, you’re okay. To fix the dimming lights, though, adding a second battery near your amps would help stabilize things. There’s no risk in having a battery above the gas tank.

If you want to do this, connect the 1/0 power cable from your front battery directly to the second battery, then run the amps off the second battery. For grounding, do the same—ground everything to the second battery, then ground the battery to the chassis with 1/0.

Let me know if you want more details on this. Upgrading your grounds should make a big difference for now, so start with that.

@Cam
Yes, I sanded everything down to bare metal for the grounds.

Cam said:
What kind of car are you running this in?
How much power does your alternator put out?
Do you have a second battery installed?
What are the RMS wattages of your amps?

It’s a 2006 Monte Carlo.

A 1500-watt amp can pull around 150 amps. Have you done the big 3 upgrade yet? If not, that should be next on your list. Then consider a high-output alternator. Since it’s a 2006 Monte Carlo, is the alternator still the original one? If so, it might just be too old to keep up. You might be able to find a local shop to upgrade or rebuild it instead of buying a new one.