The Victron Centaur 12/20(3) is a three-output mains-powered battery charger built for installations where more than one battery bank needs automatic charging from a single unit. It runs from an AC input between 120 and 240V, so it works on UK, EU and North American supplies without switching.

Marine battery charger with three outputs

• 20A main output plus two 4A auxiliary outputs, so three battery banks can charge at the same time.
• Automatic four-stage charging: bulk, absorption, float and storage, suited to gel, AGM and flooded lead-acid batteries.
• Adaptive absorption time based on how long the bulk stage took, rather than a fixed period.
• Storage mode drops the float voltage after 24 hours to reduce corrosion and water loss during long idle periods.
• Temperature-compensated charging available with an optional sensor.
• Sealed, vibration-resistant build with protection against reverse polarity, short circuit, overheating and high AC voltage.

Transformer-based design

Centaur chargers use a transformer rather than high-frequency switching, which makes them tolerant of voltage spikes and a noisy AC supply. That suits marinas, generator-fed sites and other locations where mains quality varies.

Applications

Fits vessels with separate main and auxiliary battery banks, motorhomes and coaches with leisure and starter batteries on one charger, and standby systems with multiple lead-acid banks. Also works well on narrowboats and static caravans left connected for long periods, thanks to the storage mode.

Specification highlights

• Output voltage: 12V
• Main output current: 20A
• Auxiliary output current: 4A + 4A
• AC input voltage: 120 to 240V AC
• Weight: 4.3 kg

Installation notes

Fit by a qualified electrician or competent marine or vehicle electrician, with the AC supply correctly fused and DC cabling rated for the run length and battery configuration. Marine installs should follow applicable NMEA or RCD Directive wiring standards. Not suitable for lithium batteries unless Victron documentation confirms compatibility for that specific battery type.