Originally Posted by
Aaron IIA
A battery of any description is not strictly necessary. I have started my petrol, normal coil spark ignition (as opposed to magneto ignition), SI with absolutely no battery connected. I just had to roll start it until the engine was turning over at about 1000~1500 RPM. The generator was then generating enough electricity to power the coil. This may also work with alternator powered vehicles, but they typically only self excite when the engine has reached 3000~4000 RPM.
Aaron.