Victron 120A Battery Isolator Argodiode 120-2AC: High-Efficiency Schottky Diode Battery Isolator for Dual and Multi-Bank Charging

Reliable Simultaneous Charging Without Battery Interconnection

The Victron 120A Battery Isolator Argodiode 120-2AC is a robust diode battery isolator engineered to enable simultaneous charging of 2 separate battery banks from a single alternator, without electrically connecting the batteries together. This ensures that discharging an accessory or auxiliary battery—such as a house bank in a caravan, boat, or 4WD—will not drain the starter battery, preserving engine start capability and reducing the risk of being stranded. Unlike generic split-charge relays or basic isolators, this Victron unit uses advanced Schottky diode technology to minimise voltage drop, delivering more efficient charging and longer battery life.

Designed for 12V and 24V DC systems, this isolator is ideal for marine, automotive, and off-grid applications where reliable multi-battery management is critical. Its low forward voltage drop—approximately 0.3 V at low current and 0.45 V at rated output—reduces energy loss and heat generation, ensuring more of the alternator’s output reaches your batteries. This is a significant advantage over conventional silicon diode isolators, which can drop 0.7 V or more, leading to chronic undercharging and premature battery failure.

Advanced Schottky Diode Technology for Superior Performance

At the core of the Victron 120A Battery Isolator Argodiode 120-2AC are high-efficiency Schottky diodes, which provide a lower forward voltage drop compared to standard PN-junction diodes. This means less power is wasted as heat, and the alternator can operate closer to its intended voltage setpoint. The integrated voltage compensation diode allows you to fine-tune the alternator’s output voltage to offset the small remaining drop, ensuring batteries reach a full state of charge. This feature is especially valuable in systems where battery longevity and performance are paramount, such as in deep-cycle AGM or lithium battery setups.

Additionally, the Victron 120A Battery Isolator Argodiode 120-2AC includes a current-limited alternator energize input which is essential for modern alternators that require a DC voltage on the B+ terminal to initiate charging. Without this input, a diode isolator would block the return voltage, preventing the alternator from starting. The energize circuit provides a safe, controlled current to the B+ terminal when the engine run/stop switch is closed, ensuring reliable alternator activation.

Built for Demanding Environments

Victron’s Argo Diode isolators are constructed with a durable anodised aluminium heat sink that efficiently dissipates heat, allowing continuous operation at high currents without thermal throttling. The compact footprint—60 x 120 x 115 mm—and light weight of 0.8 kg make installation straightforward in tight engine bays or electrical compartments. Heavy-duty M8 Studs stud terminals ensure secure, low-resistance connections for high-current cables, while the 6.3 mm Faston connectors for compensation and energize simplify wiring.

All models are rated for mounting on non-flammable surfaces and are tested to withstand the vibration, temperature extremes, and salt-laden air common in marine and automotive environments. This rugged design reduces the risk of premature failure and electrical faults that can occur with lesser-quality isolators.

Key Features

• Simultaneous charging of 2 battery banks from one alternator without interconnection
• Low voltage drop Schottky diodes: ~0.3 V at low current, ~0.45 V at rated output
• Integrated voltage compensation diode to optimise alternator output
• Current-limited alternator energize input for modern alternators
• Heavy-duty M8 Studs stud terminals for secure high-current connections
• Compact, lightweight aluminium heat sink for efficient cooling
• Suitable for 12V and 24V DC systems
• Robust construction for marine, automotive, and off-grid use

Applications

The Victron 120A Battery Isolator Argodiode 120-2AC is an excellent choice for a wide range of dual-battery and multi-battery systems, including:

• Marine vessels: separate starter and house battery banks
• Caravans and motorhomes: charging auxiliary batteries while driving
• 4WD and off-road vehicles: powering winches, fridges, and camping accessories
• Commercial vehicles: maintaining separate battery systems for equipment
• Off-grid solar systems: combining multiple charge sources without back-feed

Installation Considerations

When installing a diode battery isolator, it is important to account for the slight voltage drop across the diodes. The integrated compensation diode can be used to adjust the alternator’s voltage regulator, but in some systems, additional wiring modifications may be required. For optimal battery health and charging performance, consult the Victron ‘Energy Unlimited’ book or seek advice from a qualified auto electrician or marine installer. Proper cable sizing and termination are critical to minimise additional voltage losses and ensure safe, reliable operation.

Upgrade your battery management system with the Victron 120A Battery Isolator Argodiode 120-2AC and enjoy the peace of mind that comes with Victron’s proven reliability and engineering excellence. Whether you’re outfitting a bluewater cruiser, a remote-area tourer, or a commercial fleet vehicle, this isolator delivers the performance and durability you need to keep all your batteries charged and ready.