DC bekabeling MultiRS solar vs Multi RS19

Been going back and forth on this one for a while now and could really do with some input from anyone who's actually wired up either of these units.

I'm in the planning stages of adding a Victron Multi RS Solar to my tiny house setup — looking at the 48/6000 — and I'm trying to get my head around the DC cabling differences between the standard Multi RS Solar and the newer RS19 variant.

Specifically:

• Are the DC busbar/terminal sizes the same between the two models?
• Does the RS19 require heavier gauge cable runs given its updated specs?
• Any real-world differences in how the DC side behaves under heavy load (I'll be charging an EV via AC output so peak draw will be significant)?

I've been running a modest Fogstar Drift 48V LiFePO4 bank and the cabling I've already spec'd out is 70mm² from battery to inverter. Wondering if that holds up for either model or if I'd need to upsize for the RS19.

The Victron documentation isn't particularly clear on this side-by-side, and most of the detailed install threads I can find seem to be in Dutch 😅

Has anyone in the UK actually done a like-for-like comparison of these two during installation? Would love to hear whether the DC wiring approach changed meaningfully between them before I commit to buying.

@CarolThomas79 the DC cabling on both units is beefier than most people expect going in.

Ran the Multi RS Solar into my cabin build last spring. The thing that caught me out was the busbar arrangement — Victron's documentation suggests a setup but doesn't scream at you about cable lengths between battery and inverter. Keep them short and symmetrical, especially if you're running a lithium bank.

Worth noting the Multi RS Solar runs a higher DC voltage range than a standard Multi, so your cable sizing calculations need to reflect that. Don't just copy what you'd do for a Multiplus II.

What battery chemistry are you working with? That changes the conversation considerably. Fogstar Drift cells behave differently under load transients than a proper rack battery would, and the RS units can pull hard during surge.

@CarolThomas79 I've got the Multi RS Solar running in my motorhome setup and the DC side genuinely caught me off guard first time round.

Key thing people miss: the Multi RS Solar peaks at 100A charge current, so your DC cabling needs to be sized accordingly — I'd say 70mm² as an absolute minimum for any reasonable run length, and don't skimp on the busbar connections either.

The RS19 variant handles higher PV input voltages, which changes your array design rather than the DC cabling dramatically.

One thing I'd strongly recommend — fuse as close to the battery as physically possible. I use a 250A MIDI fuse in mine. Victron's own documentation is surprisingly vague on this and I've seen people under-fuse these units which makes me genuinely nervous.

What battery bank are you pairing it with? That'll affect the cable sizing conversation significantly.

@CarolThomas79 spent three days rewiring my narrowboat because I underestimated the DC cable run length on the Multi RS Solar — turns out "close to the battery" means actually close, not "close-ish by boat standards."

@OffGridGeek that narrowboat wiring pain is real — been there myself. Worth flagging for @CarolThomas79 that the busbar layout matters a lot in confined spaces, especially if you're retrofitting rather than building fresh.

One thing I'd add that hasn't been mentioned: think carefully about your negative cable routing on the Multi RS Solar specifically. The terminal positions can make symmetrical cable runs tricky depending on your battery bank orientation. I had to rethink my entire layout when I fitted mine.

Also check your fuse sizing against the actual DC input rating rather than just going off the inverter output — caught a few people out on here before. Fogstar cells in particular can deliver serious surge current that your cabling needs to handle comfortably.

What's your battery bank config looking like? That'll influence a lot of these decisions.

@CarolThomas79 one thing nobody's mentioned yet — cable sizing on the DC side isn't just about current rating, it's about voltage drop over the run. With the Multi RS Solar's higher DC input range (up to 62V on the solar side), you might think you've got headroom, but your battery-to-inverter cables still need to be sized for peak draw at your lowest battery voltage, typically around 44V for a 48V LiFePO4 system.

I'm running Fogstar Drift cells in my garden office build and initially went with 35mm² cables — swapped to 50mm² after running voltage drop calculations and the difference under load was measurable.

Use the Victron cable sizing calculator and factor in your full cable run (both positive and negative legs). A lot of people only count one way.

What's your anticipated peak load and cable run distance?