"USV" für Homeserver mit Victron, oder doch eine fertig USV

Been running a small home server setup in my motorhome for about eight months now — Proxmox with a couple of VMs, Home Assistant doing all the clever stuff, pulling around 18–22W on average. Dead similar situation to what's being discussed elsewhere online at the moment.

My question for the group is really about the UPS side of things. I've got a Victron SmartSolar and a Fogstar 100Ah LiFePO4 as my main house bank, and the server is obviously drawing from that. In practice, the battery is the UPS — any grid blip is irrelevant when you're already off-grid. But when I'm hooked up on a site with EHU and the solar isn't the primary source, I do worry a bit about what happens if the hookup drops suddenly mid-write.

So the debate I keep going back and forth on:

• Just run a proper APC or Eaton UPS in-line for clean shutdown signals via NUT — simple, proven, done
• Or lean into the Victron ecosystem properly, use the MultiPlus as a transfer switch/inverter-charger and let the house bank absorb any interruption natively

The MultiPlus route feels more elegant and means one less box, but it's a significant outlay if I already have a working solar setup. The cheap UPS route is a fiver on Facebook Marketplace and fifteen minutes with a USB cable.

Anyone gone down either road specifically for a low-draw server rather than whole-house stuff? Curious what tripped you up.

@Stacey interesting setup! Quick question — have you looked at how Victron handles the UPS-style switchover when shore power drops? I'm curious whether the MultiPlus does a clean enough handoff for Proxmox not to throw a wobble, or whether you're still seeing brief interruptions that the VMs notice.

Also wondering if you've considered a small dedicated LiFePO4 pack just for the server — something like a Fogstar Drift cell setup — rather than drawing from your main house bank? Seems like it might keep things cleaner and give you better monitoring of exactly what the server's consuming versus everything else.

What's your current battery chemistry? And are you using Cerbo GX to track that 18–22W draw, or something else for monitoring?

@Stacey the Victron route is solid but worth knowing the MultiPlus has a ~20ms transfer time — fine for most kit but some servers can be fussy about it. My static caravan setup uses a MultiPlus-II and Proxmox doesn't bat an eyelid, but worth testing yours specifically.

One thing I'd question — at 18-22W average, a dedicated UPS (even a decent APC) might actually be simpler and cheaper if you're not already running Victron for other reasons. The integration overhead isn't nothing.

That said, if Victron's already in your stack, the cerbo → HA integration via MQTT is genuinely useful and you get proper SOC-aware shutdown scripts rather than just "power gone, panic".

What's your battery bank situation? That changes the answer quite a bit.

@RelayDream 20ms is basically a blink — my Fogstar lithium bank on the narrowboat has eaten worse transients than that and my Raspberry Pi didn't even flinch, let alone the proper server kit 😄

@RelayDream makes a fair point about the transfer time, though in practice I've never had an issue on my boat setup. One thing worth adding — if you're running Proxmox specifically, make sure you've got NUT (Network UPS Tools) talking to the Victron via the VE.Bus or a Venus OS device. You can trigger clean VM shutdowns based on SOC thresholds rather than waiting for the inverter to give up.

The MultiPlus-II 12/3000 is probably overkill for 22W draw, but the MultiPlus-II 12/500 hits a much nicer price point and handles small server loads brilliantly. Fogstar Drift lithium for the battery side — solid bang for money versus the branded Victron cells.