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

I've been running a Yamaha EF2000iS for a couple of winters now as a backup when the panels are producing next to nothing for days on end. Mostly use it to top up a 200Ah lithium bank when the SOC drops below about 20%. It's quiet enough not to annoy the neighbours and sips fuel pretty efficiently — getting roughly 8–10 hours out of a litre of petrol at low load, which I'm fairly happy with.

What I'm trying to work out is whether it's worth running it through a proper battery charger (currently using a Victron Blue Smart 30A) or just plugging a couple of appliances directly into it and letting the solar deal with battery charging when conditions allow. The direct route obviously saves on conversion losses, but I do like keeping the battery topped up as a priority. Anyone gone down the route of using something like a Victron MultiPlus to manage this more intelligently?

Also wondering about fuel storage over winter — I've got two 10-litre jerry cans in the shed treated with Startron stabiliser, but I'm a bit unsure how long petrol really stays usable in practice. Some people say 3 months, others reckon 6+ with stabiliser. What's your experience been?

Reply by DaleBen:

@DalesSolar snap! I've got a Honda EU22i paired with a 280Ah LiFePO4 bank and it's been an absolute lifesaver during those grey January weeks we seem to be getting more of lately.

One thing I'd add that took me a while to work out - run the genny at closer to its rated load rather than just ticking over. I was letting mine potter along at minimal load thinking I was saving fuel, but it's actually more efficient (and kinder to the engine) to charge hard for a shorter burst then shut it off. Paired with a decent DC-DC charger or a proper mains charger with generator mode, you can shift a surprising amount into the bank in an hour or so.

What charger are you using to interface between the genny and the lithium bank?

Reply by DonnaGibson67:

Great thread this! I've been doing something similar up in Northumberland for about eighteen months now. One thing I'd add that nobody's mentioned yet — keep an eye on your charge rate relative to the generator's actual output under load. I made the mistake early on of running my Victron charger set too aggressively, which meant the genny was constantly struggling and running inefficiently. Dropped the charge current down a bit and it runs much smoother, uses noticeably less petrol, and the runtime per tank improved considerably. Also worth storing a decent fuel stabiliser if you're leaving it sitting between uses through the milder autumn weeks — I had a carburettor issue second winter that was entirely my own fault for neglecting that! @DalesSolar what SOC threshold do you typically kick yours on at?