Nordhavn 76 Inverter/Charger Upgrade: Twin Victron MultiPlus-II 5000W Units, Split-Phase 240V Power, and Cerbo GX Monitoring on M/V Trixie

A Nordhavn 76 is a serious long-range passagemaker, and its electrical system has to match that ambition. When the owner of M/V Trixie came to Marine Electric Systems, the boat was still running a pair of aging Xantrex inverter/chargers, a legacy battery monitor, and an AC transfer switch that had begun to fail. We replaced the entire inverter/charging and monitoring core with a modern Victron platform: two MultiPlus-II 24V/5000VA inverter/chargers configured in parallel for 120/240V split-phase output, a 1000A Victron SmartShunt watching the house bank, and a Cerbo GX with a GX Touch 70 display tying the whole system together and reporting to Victron's VRM portal for remote monitoring from anywhere. This upgrade is phase one of a two-phase modernization of Trixie’s electrical system — it deliberately builds a lithium-ready foundation for a new house battery bank scheduled to go in next year.

The system at a glance

• Vessel: Nordhavn 76 long-range motor yacht Trixie
• Inverter/chargers: 2 × Victron MultiPlus-II 24V / 5000VA / 120V, paralleled for 120/240V split-phase output
• Combined inverter capacity: ~10 kVA (roughly 8,000W continuous)
• Battery monitor: Victron SmartShunt 1000A / 50mV, monitoring house-bank state of charge
• System monitoring: Victron Cerbo GX MK2 with GX Touch 70 display at the main distribution panel
• Remote monitoring: Victron VRM portal over WiFi
• AC source management: New 65A rotary selector switch for forward shore power, aft shore power, and boat power
• Communications: Cat 6 backbone between inverters, SmartShunt, and Cerbo GX, with USB signal extenders over the long run to the pilothouse
• Grounds & neutrals: New junction box and terminal strip; all AC grounds and neutrals re-terminated to a correct, single reference
• Replaced: Two Xantrex inverter/chargers, old shunt, old fuse holders, obsolete comms cabling, and a faulty AC transfer switch
• Phase two (2027): New lithium (LiFePO₄) house battery bank — this platform was built to be ready for it

Why upgrade the inverter/charging system on a Nordhavn 76

Boats of this size and vintage were often wired for a different era of onboard electronics. The original Xantrex inverter/chargers on Trixie had served their time, but they were no longer the right tool for a modern liveaboard load profile, and they gave the crew almost no visibility into what the electrical system was actually doing. Just as importantly, the AC transfer switch that decided between shore power and inverter power had become unreliable — and on a vessel that spends real time away from the dock, a flaky transfer switch is not a nuisance, it’s a liability.

The goal of this project was straightforward: replace the inverter/charging and monitoring core with a platform that delivers clean, ample split-phase AC power, recharges the house bank quickly and intelligently, and reports every parameter — state of charge, AC loads, DC loads, charge and inverter status — to a single screen and to the owner’s phone. On a boat with the complexity of a Nordhavn 76, that visibility is worth as much as the power itself.

Assessment and keeping the boat powered during the work

Every good refit starts with understanding what’s already there. On a vessel this size, the existing wiring told a long story, and one detail stood out immediately: the AC neutrals throughout the boat were all tied together in a single shared arrangement rather than kept properly separated. We flagged this with the owner and corrected it as part of the rebuild, because clean neutral and ground referencing is fundamental to how a Victron inverter/charger’s ground relay and transfer behavior work safely.

Before removing anything, we built a temporary pass-through box and installed a bypass breaker so that shore power stayed available to the rest of the boat while the inverter system was torn out and rebuilt. On a liveaboard-capable yacht, keeping the lights, refrigeration, and outlets alive during a multi-day job isn’t a luxury — it’s the difference between a smooth project and an unhappy owner.

Out with the old: removing the legacy inverter and monitoring gear

With the bypass in place, the old equipment came out: both Xantrex inverter/chargers off the lazarette bulkhead, the old battery-monitor shunt, the original inverter fuse holders, the obsolete communication cabling that ran between the inverters and the control panel, and the failed AC transfer switch. Clearing all of it out first gave us a clean, well-understood foundation to build on — and freed up the exact bulkhead real estate we needed for the new units.

Twin Victron MultiPlus-II 5000W inverter/chargers in split-phase

The heart of the upgrade is a pair of Victron MultiPlus-II 24V / 5000VA / 120V inverter/chargers, mounted in the original equipment location on the lazarette bulkhead. Fitting two large inverter/chargers into the footprint the old units left behind took careful measurement — the space against the bulkhead is tight, and both units had to sit square, secure, and with room to breathe for cooling.

The two units were programmed to run in parallel and configured for 120/240V split-phase output. That’s the key to this installation: a single 120V inverter can’t serve the 240V equipment found on a yacht of this class, but two MultiPlus-II units working together produce two 120V legs 180 degrees out of phase — giving the boat a full 120/240V split-phase supply straight from the battery bank. Combined, they deliver roughly 10 kVA of inverter capacity (on the order of 8,000 watts continuous), enough to run heavy AC loads underway or at anchor without starting the generator.

To integrate them properly, we inspected the existing DC cabling and overcurrent protection to confirm the conductors and fuses were correctly sized for the new units, relocated the inverter breaker, terminated the AC input and output circuits, and installed a Victron battery temperature sensor and voltage-sense wiring so the charger regulates against real battery conditions rather than assumptions. A Cat 6 cable links the two inverters for parallel and split-phase coordination.

Want to understand how these units are sized and specified? See our companion guide on how to choose a Victron MultiPlus or MultiPlus-II inverter/charger for your boat, or browse the full lineup in our Victron inverter/chargers collection.

House-bank monitoring: a 1000A Victron SmartShunt

You can’t manage what you can’t measure. To give Trixie’s crew a true, continuous read on the house bank’s state of charge, we installed a Victron SmartShunt 1000A / 50mV in the house-battery negative cable. Power and voltage-sense wiring runs from the house bank to the shunt with inline fuse protection, and a second voltage-sense lead monitors the engine start battery — so both banks are visible on one system.

The SmartShunt is far more than a voltmeter. It counts every amp-hour in and out of the bank to report an accurate state-of-charge percentage, time-to-go, and historical data — the kind of information that turns “I think we’re okay” into a number you can trust. We updated its firmware and programmed it to the house bank’s parameters during commissioning, then fed its data into the wider Victron network. When the lithium bank arrives in phase two, the same shunt is simply reprogrammed to the new chemistry. You can add the same Victron SmartShunt to your own boat from our online store.

The brain: Victron Cerbo GX and GX Touch 70

Every component in the system reports into a Victron Cerbo GX MK2, installed in the pilothouse next to the main distribution panel and powered from a dedicated, always-on DC circuit with inline fuse protection. The Cerbo is the hub that lets the inverters, the SmartShunt, and the batteries all speak the same language and appear on one screen.

That screen is a Victron GX Touch 70, mounted at the main panel where the crew actually stands. Because the existing panel cutout didn’t match the new display, we custom-fabricated an acrylic mounting panel so the Touch 70 sits flush and finished, as though the boat came that way. From here the crew sees live shore-power and inverter status, AC and DC loads, and house-bank state of charge — voltage, current, and watts — all at a glance.

Getting the SmartShunt’s data forward to the pilothouse across a boat this large took some engineering. We ran a VE.Direct-to-USB interface from the shunt into a USB signal extender that carries the connection over Cat 6 the long distance to the Cerbo GX, where a receiver hands it back off to the Cerbo — a clean solution to a run length that would otherwise exceed a standard USB cable. Three separate Cat 6 runs were pulled, loomed, and secured along their routes, which on a 76-foot vessel meant lifting multiple floor panels (several with seized fasteners that had to be drilled out) and finding a workable path around the engine room. To learn more about this hub, read our guide on why every boater needs a Victron Cerbo GX.

Remote monitoring with Victron VRM

With the Cerbo GX in place, we set up WiFi and connected the system to the Victron Remote Management (VRM) portal, then verified the link was reporting correctly. VRM means the owner — and, with permission, our team — can check on Trixie’s entire electrical system from a phone or laptop anywhere with an internet connection: state of charge, charging activity, loads, and alarms. On a boat that isn’t occupied every day, that remote visibility is one of the most valuable outcomes of the whole project. It also means that if something ever looks off, it can often be diagnosed before it becomes a problem at the dock.

AC source selection and clean power distribution

The failed transfer switch was replaced with a proper source-management solution. We relocated the inverter output breaker box and installed a new 65A rotary selector switch in its own enclosure, giving the crew clear, deliberate control over the boat’s AC sources: forward shore power, aft shore power, and boat power. Every cable and the new switch were labelled for easy identification, so the next person to open that locker — owner or technician — can understand the system at a glance.

On the distribution side, we installed a new junction box and terminal strip for grounds and neutrals, and re-terminated all the AC ground and neutral connections into it, correcting the shared-neutral condition found during assessment. All DC positive and negative wiring was routed and terminated to the inverters and fuses, new inline fuse holders were fitted, and every new run was covered in protective split loom and secured. The result is a distribution area that is not only safe and correct, but genuinely serviceable years down the road.

Programming, testing, and handover

With the hardware in, the system was brought to life methodically. We updated firmware on the inverters, the SmartShunt, and the Cerbo GX; programmed the inverters for parallel split-phase operation and to the house bank’s charge profile; and configured the Cerbo for full system monitoring. Then we tested the complete system end to end to confirm everything — inverting, charging, transfer, and monitoring — worked exactly as intended.

Finally, we walked the owner through the new system and how to use it, updated the vessel’s wiring drawings to reflect the changes, and reinstalled all the cabinetry, floor panels, and covers before cleaning up every work area. The boat went back together looking like nothing had been disturbed — only now with a dramatically more capable electrical core underneath.

Built for phase two: a lithium house battery bank

Just as important as what we installed is what this project sets up. This inverter, charging, and monitoring upgrade is phase one of a two-phase modernization of Trixie’s electrical system. Phase two, planned for next year, is the installation of a new lithium (LiFePO₄) house battery bank — and the platform we just built was chosen specifically to be ready for it.

Doing the inverter/charging and monitoring work first is deliberate. The MultiPlus-II inverter/chargers, the SmartShunt, and the Cerbo GX are all fully lithium-capable: when the new bank goes in, we simply reprogram the charge profiles to the lithium chemistry and the same hardware carries it forward. That means phase one delivers real value today while avoiding any duplicated work later.

Once the lithium house bank is installed in phase two, Trixie will gain the full benefit of the system built around it:

• Faster charging — lithium accepts far higher charge current than the outgoing chemistry, so the MultiPlus-II chargers, the generator, and the alternator can refill the bank much more quickly and with less runtime.
• Larger loads off the inverters — a lithium bank can deliver high sustained current without voltage sag, so the twin 5000VA inverters can drive heavier 120/240V loads for longer, running more of the boat from battery alone.
• More usable amp-hours — lithium delivers close to its full rated capacity, where the old chemistry gave up only about half before performance fell off. That means dramatically more genuinely usable energy from the same battery space.

In short, phase one gave Trixie a modern, monitored power core; phase two will give her the energy reservoir to match. Curious about lithium for your own boat? Learn more on our marine lithium batteries page, or read one of our full lithium refit case studies for a sense of what the finished result looks like.

The outcome

Trixie came away with a modern, fully monitored Victron power system: roughly 10 kVA of paralleled inverter capacity delivering true 120/240V split-phase AC power, intelligent multi-stage charging that recharges the house bank quickly on shore power or generator, accurate house-bank state-of-charge data from a 1000A SmartShunt, a single Cerbo GX display at the helm, and VRM remote monitoring from anywhere. Add in corrected neutrals, clean and labelled AC source selection, and fully documented wiring, and this Nordhavn 76 is set up for exactly the kind of long-range, self-sufficient cruising she was built for — with her owner always knowing precisely what the electrical system is doing. And with phase one complete, the boat is already prepared for next year’s lithium house-bank installation — the final step that will unlock faster charging, bigger inverter loads, and far more usable energy.

Frequently asked questions

How do you get 240V from Victron MultiPlus-II inverters on a boat?

You install two units and configure them in split-phase. Each MultiPlus-II produces a 120V leg, and when the pair is programmed for 120/240V split-phase operation the two legs are 180 degrees out of phase, giving a full 120/240V supply. On Trixie, two MultiPlus-II 24V/5000VA units provide this along with roughly 10 kVA of combined capacity.

What does a Victron SmartShunt do?

A SmartShunt sits in the battery’s negative cable and measures every amp flowing in and out, so it can report an accurate state-of-charge percentage, time-to-go, and historical data — far more than battery voltage alone can tell you. The 1000A model suits the large house bank on a vessel like a Nordhavn 76.

Can I monitor my boat’s electrical system remotely?

Yes. With a Victron Cerbo GX connected to the internet over WiFi, the system reports to the Victron VRM portal, letting you view state of charge, charging activity, loads, and alarms from a phone or laptop anywhere. This is especially valuable on a boat that isn’t occupied every day.

Why install the inverters and monitoring before the lithium batteries?

Doing the inverter/charging and monitoring upgrade first builds a lithium-ready foundation. The Victron MultiPlus-II chargers, SmartShunt, and Cerbo GX are all lithium-capable, so when the new LiFePO₄ house bank is installed in phase two, the charge profiles are simply reprogrammed to suit — no duplicated work, and real benefit in the meantime. Once the lithium bank is in, the boat gains faster charging, the ability to run larger loads off the inverters, and far more usable amp-hours.

Do you install Victron systems on trawlers and motor yachts in the Chesapeake?

Yes. Marine Electric Systems is an ABYC-certified marine electrical shop based at Bert Jabin’s Yacht Yard in Annapolis, MD, and we design and install Victron inverter, charging, and monitoring systems on trawlers, motor yachts, and sailboats throughout the Chesapeake Bay region and beyond.

Considering an inverter/charger upgrade, a lithium house bank, or a full electrical overhaul on your own Nordhavn or other cruising yacht? Get in touch with our Annapolis shop — we’d be glad to talk through what the right system looks like for your boat. You can also shop Victron inverter/chargers and the full Victron Energy range in our online store.