Reliable multi-battery charging without cross-discharge

The Victron Argo FET 100-2 100A Battery Isolator is a high-efficiency battery isolator designed to charge 2 battery banks from a single alternator or a single-output battery charger—while keeping each battery electrically separated. That separation is the key benefit: powering lights, a fridge or a winch from your auxiliary battery bank is far less likely to flatten the starter battery, helping improve vehicle reliability for touring, marine and off-grid power setups across Australia.

Unlike traditional diode splitters, this unit uses FET isolator technology to minimise voltage drop. In practical terms, more of your alternator’s output reaches your batteries, which can support better charge acceptance and shorter run times in real-world systems. It also avoids the common need to raise alternator voltage to compensate for isolator losses—particularly helpful when you’re integrating modern battery chemistries or managing longer cable runs.

Designed for touring, marine and off-grid electrical systems

This isolator suits common 12V and 24V automotive and marine power systems with 12/24V auto-ranging operation. It’s a strong fit for caravans, 4WD dual-battery installs, work utes, boats, and remote power cabinets where you want straightforward alternator charging distribution without tying battery banks together. Each output is independently isolated, so different battery banks can be charged simultaneously while remaining protected from mutual discharge paths.

Helps alternators start charging when split charging is installed

Some alternators require a sense/return voltage on the B+ output to begin charging. When an isolator is installed, that return path can be reduced—occasionally leading to delayed or no alternator start-up. This unit includes an alternator energise input to assist with alternator excitation in these scenarios, supporting stable charging behaviour when the engine run/stop circuit is engaged. This is particularly relevant in modern vehicles and certain marine alternator configurations.

Installation notes that protect performance

As with any high-current battery isolator, overall charging performance depends heavily on cable sizing, connection quality and cable length. Keeping cable runs short and selecting an appropriate conductor cross-section helps reduce voltage drop in the wiring so the benefits of low-loss FET switching are preserved. For best results, follow Victron wiring guidance and use properly crimped lugs, secure fasteners and sound corrosion protection—especially in coastal and marine environments.

Key features

• Simultaneous charging of 2 battery banks from one alternator or charger
• FET technology for very low voltage drop compared with diode splitters
• Battery bank isolation helps reduce the risk of draining the starter battery from auxiliary loads
• 12V/24V system compatibility with auto-ranging operation
• High-current terminals for secure connections in demanding automotive and marine installs
• Status indication to support quick checks during commissioning and fault-finding

Very low voltage drop (typically around 0.02V at low current, averaging about 0.1V at higher currents) helps maximise charging voltage at the batteries compared with diode isolators.

Alternator energise input can assist alternator start-up in systems where the alternator needs B+ voltage present to begin charging.

Build a more dependable dual-battery or multi-battery system

If you’re planning a dual-battery split-charge setup and want a proven way to distribute alternator charging while keeping battery banks isolated, the Victron Argo FET 100-2 100A Battery Isolator is a practical, low-loss solution. Add it to your setup to support cleaner power management and more confident starts on the road or at sea.