Electrical Problem

[ctt0002 10+ year member]

I have a 145 amp alternator. I haven't done the big 3 yet because the wires in my car is hella confusing. My setup is 2 12" jbl gto series sub with a visonik v4000vd amp. I'm running 4g wire but i'll be upgrading soon. Maybe 2g or 0g wire, depending if i can fit the 4g wire through my car or not. The battery under the hood is a 770cc from walmart.

So this is my problem. Inside the car (no matter if audio is on or off), i'd notice that the interior lights would dim on intervals. However when the audio is on with my music blasting, as long as i'm giving the motor gas everything is ok. As soon as i step on the brakes, my amp would cut out. Again the interior lights are dimmed.

Now if i add a 2nd battery in the trunk. I'm thinking about getting a marine battery, one of those big ones cause they're only $100 compared to these car audio batteries, its really cheap. If i wire from the battery that is under the hood, + to + and - to -, to the marine battery in the trunk, would this solve my problem?

First thing is first, i know i need to get the ddm out and read my voltage. What else do i need to do to determine what exactly is going on? How can i check my alternator to make sure that its putting out the correct amp? I know it won't be close to 145 amp but at least 100 amp or something like that right?

Also, i forgot to mention. My amp is not turned up either. The gain is set to maybe 1/4 up. no where close to the half up.

What are some things that i should check? Any help would be nice. Car is a 1994 lexus ls400

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[ctt0002 10+ year member]

nobody has any suggestions?

 

[Alrojoca 10+ year member]

I think you pretty much answered your questions, the first step would be to replace the 4 g wire with 0 gauge, then do the big 3, a local shop could assist you with the big 3 if you can't handle it, and they should not charge much unless their minimum charge is a high price. At the same time you need a Deep cycle battery (marine battery) and the same local shop could advice you about hooking up the existing battery to supply power to your amp assuming you still have issues after replacing the 4 gauge wire and doing the big 3. The alternator would be the last step if the issue continues.