Mastervolt BI1203 BI Series Battery Isolator 120 Amp 3 Battery

The Mastervolt BI1203 is a compact, solid-state battery isolator engineered for marine, RV, and off-grid setups. It splits charging across three independent banks with minimal energy loss, delivering reliable power from your charger or alternator in 12V or 24V configurations.

• Three independent battery outlets: Independent charging and battery management for three banks, preventing cross-talk and ensuring targeted charging.
• Solid-state, corrosion-proof design: Compact enclosure with aluminium heat sinks for long life and minimal wear.
• High charging capacity: Max 80 A from the charger and 120 A from the alternator to support multi-battery installations.
• Diode technology with voltage drop compensation: Diode drop (~0.6 V) is automatically compensated by the connected charger/alternator output to maintain efficient charging.
• Automatic voltage drop compensation support: Standard with Mastervolt Mass battery chargers and Alpha Pro regulators for consistent performance.
• Easy installation: Molded diode splitters, end plates with connection lugs, and solid bolt connections with nuts and locking rings simplify setup.
• Battery Watch / Charge Mate functionality: Monitors battery condition and can act as a main switch for simplified system control.
• Versatile 12/24 V operation: Ideal for onboard systems with two or more batteries that must be charged independently.
• Compact dimensions and weight: 8.1 x 5.5 x 3.1 inches, approximately 2.9 lb.

By distributing charging across three independent banks while minimizing energy loss, the BI1203 helps extend battery life and reliability in boats, RVs, and off-grid setups. Independent charging prevents cross-talk between banks, and the built-in monitoring and main-switch capability simplifies system control. The combination of diode technology, voltage drop compensation, and robust solid-state construction ensures consistent charging performance in demanding environments.