Running multiple batteries

I have a total of 4 batteries and wondered how to connect them to the alternator, at the moment I have the 2 batteries under the hood connected to the alternator and the rear 2 batteries connected together, and my voltage never drops below 12.4 but yet my lights still dim, I'm going to get a mechman elite 370, after wired correctly if not done already stop headlight dimming?

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02 escalade dual optima Infront
2 kinetek hc2000
4 12" sa sundown
2 cab 1600.1 / audiocontrol Lc8i/stock deck
Big 3 , 2 runs front to back

All the 12V batteries need to be connected in parallel as you have them now. Each additional battery you add to your vehicle will put an additional load on the alternator, so upgrading the alternator as you intend to do will do the most to meet your high current demands when the vehicle is running. If you do not need so much reserve power (running electrical components when the vehicle is not running), you may find two batteries, or even just one battery, to be sufficient with your new alternator.

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~wirewise~ Verify all wiring with your meter before making any connections!

Thank you, yes I have a 2000 watt power inverter for PS4 and misc stuff, so I should wire all the batteries together then have runs coming off just 1 battery to the alt? , and I also have a 500 amp battery isolator, I know that reserves battery power while vehicle is off but would that help stable my voltage and how would I wire it if I edit so? Thanks for the help in advance

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02 escalade dual optima Infront
2 kinetek hc2000
4 12" sa sundown
2 cab 1600.1 / audiocontrol Lc8i/stock deck
Big 3 , 2 runs front to back