BI 1203-S

176.00  be PVM

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 aluminium 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.


BI 1203-S. Onboard systems usually consist of two or more batteries that function independently when powering the 12 or 24 V 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 main switch).

Mastervolt’s 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 battery chargers and Alpha Pro MB charge regulators come as standard with automatic voltage drop compensation.

General specifications
Number of battery outlets 3
Dimensions, hxwxd 207 x 140 x 80 mm
8.1 x 5.5 x 3.1 inch
Weight 1.3 kg
2.9 lb
Technical specifications
Max. output battery charger 80 A
Max. output alternator 120 A
Compensation diode yes
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