The Victron Centaur 12/40(3) is a three-output, mains-powered battery charger built for 12V battery banks with a combined output of up to 40A. It suits marine, vehicle and off-grid installations where separate battery banks need controlled charging from one unit. The 120-240V AC input range covers UK and international mains supplies without manual switching.

Key features of the Victron Centaur charger

• Output, 40A total across three independent outputs, so a main bank and two auxiliary banks can charge at once.
• AC input, 120-240V, suited to UK, European and North American supplies.
• Charging algorithm, four-stage adaptive process (bulk, absorption, float, storage) that adjusts to battery condition.
• Battery compatibility, works with flooded, gel and AGM lead-acid batteries.
• Temperature compensation, supports an optional sensor input for environments with temperature swings.
• Protection, microprocessor control guards against overcharge, short circuit, reverse polarity and high temperature.
• Build, wall-mountable enclosure weighing 6.4kg, suited to permanent installation in confined spaces.

How the charging stages work

Bulk charge applies the full 40A output to bring the battery up to voltage quickly. Absorption then holds voltage steady while current tapers, giving a full charge without gassing. Float and storage modes hold safe resting voltages for longer periods, which suits standby and seasonal use.

Three outputs, one charger

Each output is managed independently, so the unit can prioritise whichever bank needs it most without overcharging the others. On a vessel this covers a starter battery, a domestic bank and a bow thruster or generator start battery from a single charger, removing the need for battery-to-battery chargers or split charge relays in many setups.

Applications

• Marine vessels with separate starter, domestic and auxiliary battery banks.
• Motorhomes and coaches needing simultaneous chassis and habitation battery charging.
• Off-grid cabins and outbuildings with mains or generator power for periodic charging.
• Commercial vehicles with multiple 12V battery systems.
• Standby power installations where batteries must stay at full charge over long periods.

Installation notes

Fit this charger through a qualified electrician or marine electrical engineer, connected to a correctly fused and earthed AC supply per local wiring regulations (BS 7671 in the UK). Size battery cabling for the 40A output and keep runs short to limit voltage drop. If used, fit the optional temperature sensor directly to the main bank's battery casing. Avoid locations exposed to direct water ingress or with restricted ventilation.

What's included

• Victron Centaur Charger 12/40(3) 120-240V unit