The Victron Argofet 100-3 is a FET-based battery isolator that charges three separate battery banks from a single alternator or charger, with no voltage drop penalty. It suits marine, vehicle and off-grid installations where independent battery banks need to stay isolated from each other while sharing one charge source.

Key features

• Three outputs, charges three independent battery banks from a single input, with full isolation between banks
• FET technology, eliminates the 0.6V to 0.7V voltage drop found in diode-based isolators, so each bank gets the full charge voltage
• Current rating, 100A continuous across the combined output
• Alternator protection, built-in circuit prevents voltage spikes if the unit is disconnected under load
• Housing, compact aluminium casing suited to engine bays and confined spaces
• System voltage, compatible with 12V and 24V systems

Product overview

Diode isolators drop around 0.6V to 0.7V on every charge path, which means connected banks never quite reach full charge voltage. Over time this shortens battery life and reduces usable capacity. The Argofet 100-3 uses MOSFET technology instead, so the alternator or charger's full output voltage reaches each bank.

Three output banks from one input suits a typical setup of a starter battery, a domestic bank, and a third bank for a bow thruster, generator start or additional load. Each output stays isolated, so a deeply discharged bank cannot pull down voltage on the others. The alternator protection circuit matters here: disconnecting a battery from a running alternator can send a damaging voltage spike back through the system, and this circuit suppresses that risk.

The aluminium housing dissipates heat without needing a cooling fan under normal conditions, and it is compact enough for tight engine compartments.

Applications

Fitted on marine vessels with separate starter, domestic and thruster banks run from one alternator; motorhomes and campervans isolating the starter battery from leisure banks; off-grid vehicles or plant equipment with multiple banks serving different loads; and any setup where one charger must feed three banks without cross-discharge.

What's in the box

• 1 x Victron Argofet 100-3 FET battery isolator

Installation notes

Fitting should be carried out by a qualified auto-electrician or marine electrician working with high-current DC systems. Torque connections correctly and fuse each output cable close to the battery terminals. Mount on a surface that allows heat to dissipate, and confirm 12V or 24V system compatibility before wiring in. Do not disconnect battery banks while the alternator is running, even with the protection circuit fitted.