I was at a local steam threshing and antique show Saturday.
I saw two fellows starting a big open crank, hit and miss, stationary engine.
This one had about a 12 inch bore by atleast 12 inch stroke and flywheels of atleast 8 ft diameter.
Those guys kind of scared me a bit, they would monkey climb the outer rim of the flywheels and ride it down to let their weight turn that big engine. They would hop off about 45 degrees before the thing hit TDC and fired.
A great running old engine, "KAWHOOMP"!!!, then whoosh, whoosh whoosh for about 10 seconds until it needed to fire again. Painted green, but no identifing logo or name on it anywhere.
Late in the afternoon, I walked by the big engine again, it was shut down and no one around, so I had time to look the old engine over a little closer.
This engine had the typical moving points, low voltage igniter system like the old JD stationary engines with low tension mag had.
Only thing, this engine did not have a mag, it had battery ignition.
It had a small 12V battery with a wire running to a greasy old generator field housing sitting on the wood engine deck with fields still in place.
One wire went from a battery post to one field lead, aanother wire came from the other field lead to the moving terminal of the igniter. Another wire provided a return path from a bolt on the engine to the other battery terminal .
I was a bit puzzled by the old greasy field coils part in the ignition system, until I realized that with the igniter points closed, those old field coils would see 12V current flow and build up a magnetic field. When the points open, the magnetic field in the coils would collapse and cause a voltage spike of several hundred volts that would flash across the slightly open igniter points and light off this old engine.
I got a quick education about this type of ignition system and had to chuckle abouts the owners ingeneous use of a scrap generator part to make it work.
A few years ago I saw an ignition coil in a museum labled as for an early stationary engine. It appeared to have no secondary winding and terminals, so I wondered how it could work ?
I got my education yesterday :-)
I remember reading in vintage engine catalogs about how this type of battery ignition was standard on many engines, with a magneto being an extra cost option.
Overall a fun and educational day. :-)