How much could my electrical handle?

[SpeakerBoy 64]

I'm curious as to what I could upgrade to with my current electrical system. I currently have zero issues with voltage at full tilt with all lights and a/c on blast, steady 14.0 with my AB PH-4000 and Lanzar Vibe 231 (ick, yes eww)

 

I have two group 65's and a group 29 ran with zero, big three with 200a alt. Batts are under backseat, so pretty short runs in my mountaineer. I used less than 30ft of wire (direct runs both positive and negative).

How can I estimate this myself for future reference?

Edited June 13, 2016 by SpeakerBoy