Anyone else using a small inverter generator as emergency backup alongside their solar setup?

Picked up a Honda EU22i a few months back as a winter fallback when the panels just aren't pulling enough. Running it through a 30A mains charger into my 200Ah lithium bank when we get a run of grey days. Works a treat honestly — fills the batteries in a couple of hours and the Honda is whisper quiet compared to the old suitcase genny I had before.

My question is around runtime and fuel use. I'm getting roughly 3-4 hours per litre at around 50% load, which seems decent, but I'm wondering if anyone's found a smarter way to manage the charge cycle. Right now I just run it until the BMS shows around 95% and then shut it off manually. Feels a bit clunky and I'd rather automate it somehow — maybe tie it into the Victron system I've got (a Multiplus-II 3000).

Has anyone set up the Victron generator start/stop feature to control a Honda EU22i or similar inverter genny? I know the Multiplus can send a relay signal but I'm not sure the Honda has any kind of remote start capability without third-party mods. Keen to hear what setups people are running, particularly through UK winters where solar alone just doesn't cut it.

@Davo2 similar setup here on my static, though I went the Victron route — running the generator output through a MultiPlus 800 rather than a standalone charger. The advantage being the inverter/charger handles the absorption and float stages properly rather than a dumb charger potentially overcharging the Fogstar cells.

One thing worth checking: what's your charger's input power factor correction? Some cheaper units draw quite dirty power which can make generators hunt and surge, shortening engine life. Honda's inverter output is clean enough that it usually tolerates it, but worth monitoring.

Also — have you looked at setting a minimum SOC trigger so you're not running the generator unnecessarily? With Victron's VE.Configure you can automate start/stop if you add an appropriate relay. Saves a lot of manual faff over winter.

Good thread this. I've got a Yamaha EF2200iS doing similar duty — kicks in when the bank drops below 20% after a few grim days. One thing worth mentioning that nobody's touched on yet: keep an eye on your generator's runtime at partial load. These inverter gennies are efficient but they're happiest when you're pulling at least 50% of rated output. If your charger's only drawing 300W from a 2kW machine you're running rich and sooting up the engine over time. Either size your charger to match better or just run shorter, harder sessions rather than trickling away for hours. Also worth having a proper transfer switch or at minimum a good interlocked setup so you're never backfeeding accidentally. @Compo's Victron route is the cleanest solution if budget allows — the generator management features on the Multi are brilliant for automation.

Solid setup @Davo2 — the EU22i is a proper bit of kit, very fuel-efficient at partial load which matters when you're running it for a few hours into a charger.

One thing worth considering: if you ever want to get more out of the generator runtime, look at matching your charger's absorption stage to when the genny is actually working hardest. I run a Victron IP22 on my narrowboat and timing it right means I'm squeezing more kWh per litre.

Also — welcome to the forum! Looks like this is your first post. Great topic to kick things off with, lots of knowledgeable folk here who've been through exactly this kind of winter-backup headache.

What capacity is the mains charger you're running currently? That'll make a big difference to how quickly you're recovering the bank between grey spells.

Great thread @Davo2. One thing worth considering if you haven't already — look into whether your inverter/charger has a generator input setting you can tweak. I've got an Outback running alongside my panels and had to dial the charge acceptance rate right down initially, as the generator was struggling under the full load the charger wanted to pull. Once I dropped the input current limit to about 80% of the generator's rated output, it ran much happier and actually used less fuel overall.

Also worth keeping an eye on runtime hours and doing the oil at the recommended intervals — easy to forget when you're only firing it up occasionally through winter. Mine caught me out second season when I'd let it slip. These little inverter generators are brilliant kit but they do appreciate a bit of attention.

Running a Honda EU22i into a 30A charger is a bit like using a Ferrari to deliver milk — works brilliantly, just feels slightly excessive until January rolls round and you're parked in a field in Wales staring at 4% SoC wondering why you didn't buy a bigger generator sooner.

My Victron MultiPlus handles the AC coupling

Had almost exactly this setup last winter on a long trip through Scotland — three days of solid grey skies near Loch Ness and the Honda was earning its keep.

One thing I'd add that nobody's mentioned: fuel storage logistics matter more than people expect. I keep two 10-litre jerry cans in an external locker and rotate the petrol every month or so to keep it fresh. Stale fuel in a small engine like that is a real nuisance.

Also worth mentioning — I eventually wired mine through my Victron MultiPlus rather than a standalone charger, so I could monitor charge current properly from VictronConnect. Made it much easier to see exactly what was going in versus what the panels were contributing on those marginal days.

@SIE_Electric the Ferrari analogy made me laugh though 😄