Victron Energy Argo FET Battery Isolators, Alternator Energize Input

Overview

The Victron Energy Argofet is a FET-based battery isolator for charging two or three separate battery banks from one alternator or single-output battery charger without connecting those battery banks together. It is a practical fit for boats with a dedicated start battery and one or more house, accessory, or service banks, where the batteries need to charge from the same source but stay electrically isolated during use.

The range covers 100A and 200A versions, with models for either 2 or 3 battery outputs. Each unit works with 12V and 24V battery systems, uses M8 bolt connections, and keeps voltage loss very low, with less than 0.02 V drop at low current and about 0.1 V at higher current.

The Argofet also includes an alternator energize input for alternators that need voltage present at B+ before they begin charging. All listed configurations share the same 65 x 120 x 200 mm housing size and 1.4 kg weight, which helps when planning space in an engine room, electrical locker, or DC distribution area.

Key features

• Charges two or three battery banks from one alternator or single-output charger while keeping the banks separated from each other.
• FET technology keeps voltage drop very low, so the alternator output usually does not need to be raised to compensate for isolator loss.
• Supports both 12V and 24V battery systems, with automatic adjustment to the system voltage.
• Available in 100A and 200A current ratings to match different alternator and charging system sizes.
• M8 bolt connections give a secure termination point for high-current DC cabling.
• Alternator energize input can power the B+ circuit when the engine run/stop switch is closed on compatible installations.
• Shared housing size across the range helps simplify mounting plans when comparing 2-output and 3-output versions.

Variants

This Argofet range is offered in four configurations based on current rating and the number of battery outputs. The current rating should be matched to the alternator or charging source, while the output count should match the number of battery banks that need isolated charging.

All four versions are for 12V and 24V systems, use M8 bolt connections, and share the same 65 x 120 x 200 mm housing size and 1.4 kg weight.

• ARG100201020 (R): 100A current rating with 2 battery outputs. This version suits a two-bank layout such as one start battery and one house or accessory bank.
• ARG100301020 (R): 100A current rating with 3 battery outputs. This version suits a three-bank layout where a start bank and two separate service or accessory banks need isolated charging.
• ARG200201020 (R): 200A current rating with 2 battery outputs. This version keeps the two-bank arrangement while allowing for a higher-current charging source.
• ARG200301020 (R): 200A current rating with 3 battery outputs. This version combines the higher current rating with three isolated battery outputs for larger DC charging layouts.

Installation and setup

The alternator or charger positive output connects to the input terminal, and the battery bank positives connect to output 1, output 2, and output 3 where used. The battery negatives remain connected to the common negative bus, not through the isolator.

Cable length and cable size matter in this type of high-current DC installation. Keeping cable runs short and using cable with sufficient cross section helps limit voltage drop across the wiring, which is especially important in engine rooms and battery compartments where charging current can be high.

Compatibility and fit

These isolators are suited to 12V and 24V DC charging systems on boats that use separate battery banks for starting and onboard loads. They are useful when a start battery must remain protected from discharge caused by house loads, electronics, pumps, lighting, or other accessory circuits.

The 2-output versions fit simpler two-bank systems, while the 3-output versions support layouts with an additional service or accessory battery bank. Before installation, the current rating should be checked against the alternator or charging source output and the cabling plan for the vessel.

Use cases on board

On cruising boats, fishing boats, and workboats, an Argofet can help keep the engine start battery separated from the house bank while still allowing both banks to charge when the engine is running. It is also useful in refits where the goal is to tidy up DC charging paths without combining battery banks directly.

This is a good match for owners or installers building a clean multi-bank charging system around a single alternator or single-output charger, especially where low voltage drop and simple isolated outputs are more important than remote monitoring or network control.