Victron Energy Buck-Boost DC-DC Converter (25A / 50A / 100A)

The Victron Buck-Boost is a fully programmable DC-DC charger built specifically for vehicles with a modern “smart” alternator (regenerative braking, Euro 5 and Euro 6 engines). Those alternators swing their output voltage all over the place — sometimes too high (e.g. 15.4 V on some Mercedes), often too low to charge a service battery at all. The Buck-Boost's buck-and-boost design steps the voltage up or down as needed to hold a correct, pre-set charge voltage, so your auxiliary battery actually fills — while protecting the vehicle's starter battery from being drained.

Programmable for any 12V or 24V system

One unit handles 12 V, 24 V, and 12/24 V combinations: program it to charge a 12 V or 24 V auxiliary battery from either a 12 V or 24 V alternator/starter battery. Charge voltage and current are fully programmable via a free PC application (USB connection), and the output is governed by your charge-current setting, an input-current limiter, and the converter's temperature limit — so it never overloads the alternator. It's compatible with AGM, Gel, and lithium banks.

Engine-running detection protects the starter battery

A built-in engine-running detection system only charges when the engine is running, preventing deep discharge of the starting battery. Alternatively, the converter can be triggered by a programmable input — a D+ signal, CAN bus, or a (+)15 connection (note: the 25 A model has no CAN bus connection).

Clear at-a-glance diagnostics

Separate input and output status LEDs report exactly what the converter is doing — running, waiting on engine start, input voltage too low, over-temperature, or battery state — so troubleshooting on the road is quick. Under-voltage protection and a 7 mA power-save mode round out the design. Operating range is −25 to +60 °C.

How it compares

The Buck-Boost is the heavy-duty, PC-programmable choice for demanding commercial-vehicle and camper installs on smart alternators. If you'd rather configure and monitor from your phone, Victron's Orion-Tr Smart and Orion XS DC-DC chargers offer adaptive multi-stage charging with Bluetooth (and, on the XS, VE.Direct/GX).

Choosing your model

25 A — 25 A at 12 V / 15 A at 24 V; 0.6 kg, 165 × 120 × 30 mm (no CAN bus). 50 A — 50 A at 12 V / 25 A at 24 V; 1.4 kg, 213 × 120 × 30 mm. 100 A — 100 A at 12 V / 50 A at 24 V; 4.1 kg, 288 × 162 × 95 mm, ideal for high-capacity lithium banks needing fast recharge. All accept 10–30 V in and out.

Why buy from Blue Marine

Blue Marine is an authorized Victron Energy dealer. Every Buck-Boost ships brand-new with the full 5-year Victron warranty, free shipping, and local pickup available. Building a camper or commercial vehicle on a smart alternator? Talk to us — we'll help you size the charger and program the profile.