The Victron 25A Buck-Boost DC/DC Converter is a non-isolated converter for mobile, off-grid and vehicle-based electrical systems where input and output voltages can vary independently. It suits installers working on campervans, boats, trucks and off-grid setups that need a stable output regardless of fluctuations at the source.

Key features

• Output current, 25A continuous, using buck-boost topology so output voltage can be set higher, lower or equal to the input.
• Design, non-isolated, which avoids the losses of transformer-based isolation.
• Input range, wide enough to handle the varying battery and alternator voltages found in vehicle and off-grid systems.
• Weight, 1.03 kg.
• Monitoring, VE.Direct port for use with Victron Connect or a GX device.
• System configurations, 12V to 12V, 12V to 24V, 24V to 12V and 24V to 24V.

How it works

A standard buck or boost converter only performs correctly when input voltage stays consistently above or below the output. Buck-boost topology removes that constraint, holding a stable output even as input voltage crosses above and below it, which happens when a battery is partially discharged or an alternator output varies.

At 25A the unit can handle meaningful charge currents for a secondary battery bank. In a split-charge vehicle system it can charge a 12V leisure battery from a 12V starter circuit without the output being affected by engine-off voltage drop or engine-on alternator spikes. Because the design is non-isolated, the negative terminals of input and output share a common reference, which needs to be accounted for in the wiring design.

Integration with Victron systems

The VE.Direct port connects to a GX device such as a Cerbo GX, so the converter appears within the Venus OS dashboard alongside the rest of the installation. This suits managed off-grid or marine systems where a full overview is needed.

Applications

• Charging a secondary leisure or auxiliary battery from a vehicle starter circuit.
• Maintaining a stable 24V output from a 12V source, or the reverse, in mixed-voltage vehicle systems.
• Off-grid cabins and mobile installations where input voltage changes with battery state of charge.
• Marine electrical systems that need a regulated DC supply to secondary battery banks.
• Truck and commercial vehicle auxiliary power systems with variable alternator output.

What's in the box

• 1x Victron Energy 25A Buck-Boost DC/DC Converter

Installation notes

Fitting should be carried out by a qualified electrician or experienced system integrator familiar with DC power systems. The non-isolated design means input and output grounds are common, so incorrect wiring in systems with multiple ground references can cause faults or damage. Cable sizing and fusing need to suit 25A continuous DC current. Marine installations should follow applicable NMEA or RCD Directive wiring standards, and Victron Connect (via a VE.Direct USB adapter or Bluetooth if supported) should be used to set input and output voltage parameters before commissioning.