BI 1203-S Isolator

Onboard systems usually consist of two or more batteries that function independently when powering the 12 or 24V consumers. These batteries require independent charging with reliable battery isolators or battery combiners.

Mastervolt offers several intelligent solutions:

• Battery isolators that divide your charge current with a minimum energy loss.


• The Charge Mate for connecting and/or disconnecting two batteries.


• Battery Watch for monitoring the condition of your batteries (also usable as the main switch).

Battery isolators for conventional systems with an alternator or battery charger and two or three batteries

Mastervolts BI battery isolators are based on conventional diode technology. The diode voltage drop (ca. 0.6 V) can be compensated for by adapting the output voltage of the connected charger or alternator. Mastervolt Mass battery chargers and Alpha Pro charge regulators are standardly equipped with automatic voltage drop compensation.

Compact and lightweight

The Mastervolt BI battery isolators are compact and fully solid-state, preventing wear. The weight varies from 580 to 1300 grams.

Robust and durable

Completely corrosion-proof material with aluminum heat sinks. The electronic components are encased in synthetic materials, the BI models have molded diode splitters.

Fast installation

The synthetic end plates feature connection lugs, the solid bolt connections with nuts and locking rings ensure easy installation.