The Victron Argofet 200-2 is a FET-based battery isolator that charges two separate battery banks from a single alternator or charger, without the voltage drop found in traditional diode isolators. It suits marine, vehicle and off-grid systems where independent battery banks need to stay isolated from each other during discharge while still sharing one charging source.

Key features of the victron argofet 200-2

• Continuous current, 200A rating, suited to high-capacity alternators and charging systems.
• FET technology, removes the 0.6V to 0.7V drop typical of diode isolators, so each bank gets the full charging voltage.
• Two output channels, charges two independent battery banks at once from one input source.
• Automatic operation, no manual switching needed in normal use.
• Housing, compact aluminium casing suited to engine bay and marine fitting.
• Input compatibility, works with standard alternators or an external battery charger as the source.

How it works

Diode isolators typically drop voltage by around 0.6V to 0.7V between alternator and battery, which can leave batteries chronically undercharged. The Argofet 200-2 uses MOSFET switching to bring that drop close to zero, so each bank receives the alternator or charger's full output voltage.

Current flows from the input to both banks while charging, but the isolator stops current passing between the two banks. A starter battery and a leisure or service battery can therefore charge together without the service bank draining the starter battery once the engine is off. The 200A rating covers larger setups with high-output alternators or multiple chargers on one system.

The unit runs without active control once wired, though an alternator excitation connection is needed for correct MOSFET switching. Because the voltage drop is near zero, installers should check the alternator's regulator setting, as it will see a more accurate battery voltage than with a diode isolator.

Applications

• Marine vessels with separate starter and service banks on one alternator.
• Motorhomes and campervans needing isolation between starter and habitation batteries.
• Trucks and commercial vehicles with auxiliary battery systems.
• Off-grid setups where one charger feeds two separate banks.
• Dual-battery systems suffering undercharging from a diode isolator.

Installation notes

Fitting should be carried out by a qualified electrician or marine electrical engineer used to high-current DC work. Mount the unit somewhere ventilated, as it generates heat under load, and use cabling and fuses rated for 200A continuous current on both input and output. The alternator excitation wire must be connected correctly for the MOSFET to switch. Do not fit inside sealed or unventilated enclosures.

What's in the box

• Victron Argofet 200-2 FET battery isolator unit