Thanks oldhouseman.
Would that generator and battery bank have originally been kept in the same room like that? Those lead-acid batteries give off hydrogen gas when charging, any spark from the generator could have set them off. It would be a big bang.
I live with the 21st century equivalent of that system - solar power with petrol (gasoline) backup charger. I can post pics in a day or two if anyone is interested. My DC generator is a home-made unit consisting of a Briggs Vanguard 6hp petrol motor, belt drive to a 24 volt DC Bosch truck alternator with a home-made voltage regulator (made to someone else's design.) Interesting that the old generator in the photos is huge yet only produdes 1500 watts, mine produces 1000 watts and is tiny by comparison.
I'm a bit confused, the one in your photo says it auto-starts when load exceeds 300 watts. So what is the system - did the house run from the battery bank and the generator recharge the batteries, or did the house run direct from the generator?
thanks
Chris.