Upgrade Xantrex Factory Install to Victron

Anyone else gone through ripping out a factory-fitted charger/inverter combo and replacing with Victron kit?

My setup came with a basic Xantrex unit when I bought the place — did the job for a while but once I started expanding the battery bank it just couldn't keep up properly. Charge profiles were a bit naff and there was no proper monitoring whatsoever.

Swapped it for a Victron MultiPlus-II and honestly should've done it sooner. The difference in charge management alone was worth it, especially once I got the MPPT and Cerbo GX all talking to each other through VRM. Proper visibility of everything for the first time.

The wiring side of things is where it gets fiddly though. Factory installs tend to cut corners — undersized cables, dodgy terminations, that sort of thing. Worth budgeting time to sort all that out properly rather than just swapping the unit and hoping for the best.

Few things I'd flag if you're considering this:

• Check your existing cable runs before assuming they're adequate
• Split charging between banks (start vs house) needs thinking through carefully
• Victron's absorption/float settings make a big difference to AGM longevity
• Fogstar batteries are worth considering if you're thinking about moving to lithium at the same time

Anyone done this and kept AGMs, or did most people use the upgrade as an excuse to go lithium? Curious what others landed on — feels like a natural point to rethink the whole battery setup rather than just swap the charger.

@PennineSolar done exactly this on my motorhome — pulled out a tired Xantrex Freedom HF and replaced it with a Victron Multiplus-II 12/3000.

The wiring headache isn't the inverter swap itself, it's the system integration afterwards. Victron's VE.Bus and GX ecosystem means you'll want to budget for a Cerbo GX alongside the inverter, otherwise you're losing half the value.

Key gotcha: the Xantrex likely used a proprietary shore power transfer relay — Victron handles this internally, but verify your incoming AC cabling gauge is rated appropriately before assuming it carries over.

I'd strongly recommend pre-crimping all DC cables to correct cross-section (95mm² minimum on a 3000W unit at 12V) before the inverter even arrives. Most failed installs I've read about on here come down to undersized DC cabling causing voltage drop under load.

@PennineSolar did this on the narrowboat a couple of years back. The Xantrex wasn't terrible but the lack of any decent monitoring drove me mad — you're essentially flying blind.

One thing worth flagging that caught me out: the Freedom HF wiring gauges are often undersized for what a Victron Multiplus will actually pull at full load. Check your DC cable runs carefully before you assume it's a straight swap.

The VE.Bus integration with the Cerbo GX is where it gets genuinely impressive — you can see exactly what's happening with your bank in real time, set charge profiles properly, and the ESS assistant handles shorepower transitions beautifully.

If you're on a static caravan or boat where you're regularly switching between hook-up and battery, that seamless transfer really does make a noticeable difference to how appliances behave.

Has anyone documented the wiring gauge changes needed when swapping these units out? I'm planning something similar for my garden office setup — currently running a factory-fitted unit and looking at a Victron MultiPlus-II.

Specifically wondering:

• Did the existing cable runs cope with the new unit's rated current, or did you have to re-pull cables throughout?
• How did you handle the earthing arrangements — any complications with the neutral-earth relay inside the MultiPlus?
• Did either of you use a Cerbo GX alongside, or just the basic VictronConnect bluetooth monitoring?

@DefenderDream the Freedom HF swap is particularly relevant to me as I believe the mounting footprint is quite different to the MultiPlus range. Curious whether you fabricated a new mounting plate or found a tidier solution.

The Victron documentation is thorough but doesn't really cover the "ripping out the old stuff" side of things.

@MuddySkipper that's exactly what I'm trying to figure out for my shepherd's hut build. The hut came with a fairly basic inverter/charger combo and I'm looking at a Victron MultiPlus as a replacement — but I'm unsure whether the existing cabling from the battery bank will be adequate for the higher continuous current draw.

Does the cable gauge depend purely on the inverter's max output rating, or does the battery bank capacity factor in too? I've got 200Ah of Fogstar Drift lithium and the cabling feels quite short which I'd hope means voltage drop is less of a concern, but I genuinely don't know if the existing terminations and fusing are up to spec for a MultiPlus 12/2000.

Anyone know if Victron's own documentation covers minimum cable sizing, or is it worth getting an electrician in to assess before ordering?