Dual Battery System for 4WD: What You Actually Need
Ask five people what a dual battery system for 4WD actually needs and there's a decent chance you'll get five different shopping lists. Some of that is genuine flexibility — there's more than one way to wire a rig — but a lot of it comes down to people copying what a mate did five years ago, on a vehicle with a completely different alternator. Before spending money, it's worth understanding what each component in the system is actually doing, because the right setup for a modern dual-cab with a smart alternator looks nothing like the right setup for an older vehicle with a fixed-voltage charging system.
