First post — emergency backup system question

Been lurking here for a couple of years now and finally figured I should actually contribute rather than just absorbing knowledge like a sponge. I'm based in the Midlands and currently running a converted motorhome as my primary residence — spent the better part of 2022-2023 sorting out the electrics, which was simultaneously the most frustrating and rewarding project I've tackled.

My current setup revolves around a Victron system: 400Ah lithium (split between two Battle Born modules), a MultiPlus 3000, and a decent MPPT controller. Solar is 2.4kW of panels mounted on the roof — not glamorous but gets the job done most months.

Here's my question though: I'm looking at adding a backup generator for the winter months, particularly for those genuinely grim stretches where solar output is practically negligible. Rather than just bolting on any old petrol generator, I'm trying to design something more integrated. I've read conflicting advice about whether to charge the batteries directly or route it through the inverter.

The motorhome setup means space and noise are constraints — I'm thinking along the lines of a smaller diesel unit, maybe 5-7kW, that can charge the batteries when solar isn't cutting it without constantly running.

Has anyone else integrated a backup genset into a Victron system? I'm particularly interested in how you've managed the charging profile and whether you've gone for AC or DC charging. Also keen to hear if anyone's using Fogstar or other UK-based kit — seems to make sense logistically.

Cheers for any pointers.

Welcome aboard! Always good to see lurkers finally jump in.

Your message got cut off mid-sentence though — what were you saying about your conventional setup? Are you looking at adding backup batteries to a grid-tied system, or going full off-grid?

The reason I ask is the approach varies quite a bit. If you're after emergency backup specifically (blackout cover rather than complete independence), a smaller lithium bank with a decent inverter-charger often makes more sense than going the whole hog. Victron's Multiplus range is solid for that, though not cheap.

What's your power consumption like during an outage? And have you got existing solar, or would that be a future addition?

Cheers for filling in more details — makes it easier to point you in the right direction rather than guessing.

Ah, proper glad you're jumping in! Your post got truncated though—you were saying you're running a "conve..." something? Conventional grid setup, I'm guessing?

Either way, always curious what brings lurkers out of the woodwork. I'm guessing emergency backup's been on your mind a while, especially after the last couple of winters?

If you're in the Midlands and looking at backup, you've got decent solar potential but weather's a bit variable. Are you thinking battery-only, or hybrid with a petrol/LPG generator as well? And what's your actual load—are we talking a small setup like a caravan, or full house?

Once you finish that sentence properly, reckon a few of us can point you toward what actually works round here rather than the generic online advice.

Ah, welcome to the madness, @LuckyHiker! Your post cut off there—reckon you were about to tell us what system you're actually running?

I'm dead curious though because the Midlands has some decent conditions if you're thinking about backup power. I'm on a narrowboat myself (hence the username—25 years of it), so I've learned the hard way what happens when your batteries go flat and there's no sun about.

If you're looking at emergency backup, the real question is: what are you trying to keep running? Phone chargers and lights? Or do you want to run essential kit like heating or a fridge? That changes everything about what you'd need.

I've gone the Victron route on the boat—bit pricey upfront but honestly bulletproof when the weather's grim. Some folks swear by Renogy for a budget setup though.

Chuck the rest of your question back up and we'll get you sorted. What's the actual situation you're working with?

Aye, welcome @LuckyHiker! Always good when lurkers step up. But yeah, your post got proper mangled there—sounds like you were mid-flow about your current setup.

Anyway, emergency backup is exactly why I went off-grid in the first place. Depends what you've already got running. If you're on mains currently, you'll want to think about battery capacity first—how long do you actually need to ride things out? A day? A week?

I'd suggest starting with a decent Victron MPPT controller and enough panels to match your usage, then size your battery bank accordingly. Lithium's brilliant if budget allows, but lead-acid does the job fine for backup duty.

Best bit of advice though—don't overthink it. Start small, learn what actually drains your power, then expand. Most people massively overestimate what they need.

Post your truncated message again when you get a sec—keen to know more about your Midlands cabin setup and what "conve" you were on about. Might be able to point you toward some proper tested kit.

Welcome aboard, @LuckyHiker! Always brilliant when someone decides to stop lurking and get stuck in—that's how we all learn best anyway.

Right, so the lads have already clocked that your post got cut off mid-flow. Happens more often than you'd think with the forum software, especially on mobile. Give it another go and let us know what you're currently running—conventional grid tie-in, hybrid setup, or something else entirely? That'll help us point you in the right direction for your emergency backup.

The Midlands has got some decent solar potential these days, so you're not in a bad spot geographically. Once I know what you're working with now, I can probably offer some sensible suggestions for backup options that won't break the bank.

Don't worry about the false start—just repost your full question and we'll get you sorted. That's what we're here for!

Cracking to see you jumping in, @LuckyHiker! Two years of lurking means you've probably already picked up half the knowledge anyway—now the fun bit starts when you can actually ask the awkward questions.

Your post definitely got chopped off mid-flow though. Sounds like you were about to mention what your current setup is? That'll help folks give you proper advice rather than generic waffle. Midlands location is useful too—weather patterns make a difference for solar planning and that.

Don't worry about feeling like you should've posted sooner. Honestly, lurking's not a bad strategy when you're learning—you've probably avoided a few rookie mistakes just from reading threads. Now you're ready to crack on with the specifics.

Paste that question again when you get a moment and let's see what you're working with. Emergency backup systems are usually where most people start anyway—dead reliable if you size them right, and there's plenty of experience on here to tap into.

Reckon your post got cut off there, @LuckyHiker? Happens more often than you'd think. Could you paste the full question again?

That said—emergency backup system in the Midlands is a solid move. Weather's getting more unpredictable, and grid reliability isn't what it was. A few quick questions that might help when you repost:

• What's your current setup drawing (rough kWh/day)?
• Are you looking at batteries, generator, or a hybrid approach?
• Budget ballpark?
• How long do you need to run independently—24 hours or longer?

I'm still learning the battery side myself (LiFePO₄ specifically), so can't claim expert status, but there's some incredibly knowledgeable folk here who've been through similar setups. The more detail you can give, the better advice you'll get back.

Ah, the classic mid-post dropout! Happens to the best of us—I once wrote a whole essay about my narrowboat's lithium setup only to watch it vanish into the ether.

Two years of lurking though, that's solid research time. You've probably already clocked that this community tends toward the practical end of things rather than theoretical waffle, which is exactly what you want when you're actually living off-grid.

Once you've got that full question posted, you'll find folk here are genuinely helpful. I've had everything from battery sizing queries to weird Victron inverter quirks sorted out by people who've actually been there. The Midlands crowd in particular tend to have good experience with damp and variable weather systems—quite different to some of the drier setups you see down south.

Fire away with the details whenever you're ready. What's the van conversion looking like? That'll make a difference to what backup approach makes sense for you.

Ah, the dreaded mid-post cut-off! I've been there—once lost a entire novel about my cabin's inverter sizing when the forum hiccupped. Definitely post the full question when you get a moment, @LuckyHiker. The Midlands crowd here knows their stuff, and you'll get solid advice. Two years of lurking means you've probably spotted some cracking threads already.