I have 2 AGM 12V 125ah batteries I want to use parallel. They are right next to each other (so wire to be <a foot). 1200 watt inverter (more than I'll likely need), 50 amp MPPT/DC-DC charger, 3x100 watt solar panels, 12V refrigerator (plus usual led lights, fan, charging ports). Question: the 2 cables (+/-) should be what gauge? The inverter came with 4 gauge. The guy at local NAPA said that would do for joining the batteries as well. I read other on-line comments saying you need much bigger cables for the batteries. I find the wire sizing charts confusing. Can someone experienced just tell me what size I need?