Overloading your battery and charging system with all those extra electrical accessories added to your Jeep? Hook up one of these Wrangler NW Power Products Dual Battery Tray Systems and relieve the stress from your electrical system. Models for all 1970-05 CJ & Wrangler Jeeps. The Relay & Cable Kit includes everything to connect two batteries. The Battery Manager is an advanced cockpit control system that allows starting on one yet charging both batteries while running. It also controls an isolation relay-either double up, or isolate the batteries from each other.