Cool deal, my guess about voltages is about 8 volts cranking and jumps to 12 to 12.8 when first starts ? A rare problem with that setup is a dying battery that sits at rest at 12 volts but when starter enguages, the voltage dips so low that the starter drops out and the voltage goes up then repeats that chatter in and out. Not sure how you would detact that. Timmers may have thought of that but with more circuitry.
Don