ARCO Marine BI-1202 Battery Isolator - 120A - 1 Alternator, 2 Battery [BI-1202]BI 1202 Battery Isolator 120A 1 Alternator, 2 Battery The Arco Marine BI 1202 is an inboard outboard battery isolator that can handle 1 alternator, 2 batteries, and 120A maxrated for use with 10 to 350 amp alternators on 12, 24, or 32 volt negative ground systems. Features: 1 alternator, 2 batteries, 120A max Inboard and outboard battery isolators are solid state devices that allow electrical current to flow in one direction ONLY, thus permitting the