Go to a battery shop and get them to put a load on the battery, they will be able to tell you quickly if your in need of a replacement battery. Your alternator is what charges the battery the two together have to work with one another, put a multimeter on your battery without the motor running and it should be around 12.6 volts but not any lower, With the vehicle running you should get 14.3 - 14.5 volts. Sounds as though your battery needs replacing, look into a yellow top optima battery if this is the case.

 

I agree that it sounds like the battery is on its way out. Sometimes a load test doesn't even detect this.

 

I see. Thanks guys.
But okay, sounds good.

So then is it almost safe to say that if I were to drop, say, a YellowTop in, my dimming problem would probably be gone?

 

can't put a 100% guarantee on that, one thing though when doing your "big 3" did you use a good grounding point and short ground cable ( hopefully 4 guage at least when you did it)

 

Yeah I used as short of a cable as they had, and yes, I used 4 gauge.
They are very very well built cables as well.

Yet I didn't exactly sand the chassis ground points down.
I just screwed them back to where the manufacturer had the points.

Would sanding help significantly or is it basically just as good the way the manufacturer had it?

 

Sand the metal down benath all grounds! Imagine the resistance to grounding thru paint!? (or a couple scrathes through the paint)

 

go to a non painted surface that will give you the best results. Prep the surface at least the size of the ring terminal used for the ground and use a lock washer. Use a wire wheel on a cordless drill that will get prep the surface with ease.

 

If you want to simulate this, connect a second car battery with jumper cables to yours and see if it helps. Just don't have the other car running.

 

Nice guys!
Those were awesome responses.

I'll post results/concerns after trying them.

 

I sanded down the contact points and it helped a bit.

The LED's on the amp still blink when huge bass drops hit.
I'm guessing that the amp isn't getting the voltage it needs through the cables so it's choking off slightly...

Larger cable runs I'm guessing?