Anyone else running a garden office solar setup in their van at weekends?

I've got a Victron SmartSolar 100/30 and a pair of Fogstar 100Ah lithium batteries in my static caravan setup at home, but I've been toying with the idea of a crossover — basically using the same battery bank as a portable unit I can chuck in the back of the van for weekend trips. Wondering if anyone's actually done this or if it's more hassle than it's worth.

The batteries are connected via a Victron SmartShunt and I'm monitoring everything through VictronConnect. Pulling them in and out every couple of weeks feels like it'd wear on the cable connections over time, and I'm not sure the BMS on the Fogstars would appreciate constantly being disconnected and reconnected.

Has anyone rigged up a proper quick-disconnect system that works reliably? Thinking Anderson connectors but not sure what rating I'd need for a 12V setup drawing maybe 40A peak. Or is the sensible answer just to bite the bullet and get a dedicated van setup?

WingAndPrayer88 | 847 posts | ⭐ Trusted Member

@LisaHunt88 The Victron kit will absolutely sing in a van setup — that SmartSolar handles varying panel orientations really well which matters when you're parked up at odd angles rather than fixed on a south-facing roof.

One thing worth considering if you're doing genuine crossover use: keep an eye on your cycle counts. Lithium cells don't mind it, but if you're hammering them across two applications you'll want the Fogstar app keeping tabs on state of health over time.

Also, are you planning on relocating the batteries physically or just the controller? Running decent cable lengths between the two setups gets messy quickly. Might be worth a dedicated small bank for van use rather than humping the Fogstars back and forth every weekend.

What sort of loads are you running in the caravan currently?

SolarCol | 1,203 posts | ⭐ Trusted Member

Worth flagging that the 100/30 will handle two 100Ah Fogstar cells comfortably from a charge management perspective, but your limiting factor when doing EV charging crossover duties is going to be the inverter capacity and available panel wattage — not the batteries themselves.

I run a similar dual-purpose arrangement at my cabin and the key lesson was undersizing the load expectations rather than oversizing the hardware. If you're drawing anything meaningful for a van-based EV top-up (even just 12V trickle), you'll want to audit your realistic solar harvest window for wherever you're parked.

What's your panel array wattage currently? That'll determine whether this crossover idea is viable without significant additional spend.

MidlandsNomad | 412 posts

Done exactly this with a similar Fogstar/Victron combo — swapping batteries between a shed office and a Transit at weekends is more faff than it sounds once you've got everything cabled up properly on both ends.

Honestly ended up just buying a second bank for the van. Fogstar cells aren't that expensive and the convenience is worth it.

One thing worth thinking about — if your caravan is grid-tied with a Victron Multiplus doing any of the heavy lifting, the battery profile settings won't automatically carry over. Make sure your SmartSolar charge settings are saved properly before you unplug.

DorsetSolar | 2,156 posts | ⭐ Trusted Member

One thing nobody's mentioned yet — if you're physically moving those Fogstar 100Ah cells between locations, check your battery terminals aren't working loose over time. Done similar swaps between my narrowboat and a temporary workshop setup and the vibration from transport can be sneaky. A bit of Loctite on the terminal bolts and a proper carry handle or battery box makes life much easier.

Also worth setting up a Victron VRM profile for each "location" on the app — you can track state of charge history separately which is genuinely useful for understanding consumption patterns in each context. @MidlandsNomad did you find the BMS reset itself at all during transport? Mine occasionally threw a fault light after a bumpy journey until I figured out the cells had shifted slightly.

BrambleHermit | 847 posts

Good thread this. One thing I'd add to what @DorsetSolar is hinting at — check your BMS settings before you start hot-desking those batteries between installations. The Fogstar Drift cells are decent but if your caravan setup has been float charging at slightly different parameters to what your van's system expects, you can confuse the state-of-charge readings initially. Give them a full cycle in whichever system you're moving to first. Also worth labelling your Anderson connectors clearly if both setups use the same plug type — learned that one the embarrassing way when I accidentally ran my garden office off a half-depleted pack thinking it was fresh. Nothing dangerous, just annoying!

ThingamyBob62 | 203 posts

One thing nobody's mentioned — check your van's existing wiring before lugging those Fogstars in and out regularly. Terminals take a hammering from repeated connects/disconnects. I've got Anderson connectors on mine now, makes the whole swap dead quick and no faff with loose bolts.

Also worth thinking about where the batteries actually live during the week when they're not in the van. Lithiums are fine in a garage but keep them somewhere they won't drop below about -10°C if you're storing partially charged.

@MidlandsNomad did you find the Victron app kept its settings when you moved the MPPT between setups? Curious whether it remembers the battery profile or resets.

OffGridDoug | 1,432 posts

Worth flagging something nobody's touched on yet — your SmartSolar 100/30 will need reconfiguring if your panel array changes between the static and the van. Different orientations, partial shading, even just a smaller panel footprint will shift your charge profile considerably. I run a near-identical Victron setup in my motorhome and I keep a saved profile in VictronConnect for each physical location. Takes thirty seconds to swap over. Also double-check your absorption voltage is set correctly for Fogstar's lithium spec — I've seen people leave it at AGM defaults and slowly cook their cells over a season.

RobButler | 312 posts

Great point from @ThingamyBob62 about the van wiring — I'd extend that to think about your connection points too. If you're regularly swapping those Fogstars between the static and the van, decent Anderson connectors are absolutely worth the investment. Makes the whole crossover setup genuinely plug-and-play rather than a faff with terminals every weekend. I've been doing something similar with my Transit for about eighteen months and the time saved is considerable. Just make sure your cable gauge matches both applications — what's fine for a static install can be marginal in a vehicle context with longer runs.

Jonno45 | 847 posts

@LisaHunt88 one practical thing worth thinking about is temperature management — lithium batteries like your Fogstars don't love being left in a van over winter weekends when you're not there. If the cells drop below about 0°C and you try to charge them you can cause permanent damage. Worth checking whether your BMS has low-temp charge cutoff built in (most Fogstar units do, to be fair) but don't just assume it'll protect you in all scenarios. A cheap temperature alarm can give you peace of mind remotely. 🙂

OffGridTerry | 687 posts

Something nobody's mentioned yet — the physical connection/disconnection cycle. If you're regularly shuttling those Fogstar batteries between your static and the van, the terminals will take a beating over time. Decent anderson connectors (30A minimum, ideally 50A) are worth fitting to both setups rather than wrestling with bare terminals on a muddy Saturday morning. I did exactly this with my motorhome and the cabin backup system — runs off the same bank depending on where we are. One anderson plug on the battery, done. Makes the whole crossover approach actually liveable rather than a faff you eventually stop bothering with.