Generator polarizing question

[Leyland]

I removed the cut out this evening from the generator, used a piece of 14g wire on the 12v + battery post, and touched it to the generators output post momentarily (where the cut out would connect to). It sparked. Did this a few times to be sure... I re-installed the cut out unit onto the generator, started the car and like magic my multi-meter read voltage with the correct polarity for my 12v - ground system!! HOWEVER…. It read 10,20,30+ volts at the cut outs battery tab!! I connected the yellow and black generator wire, and switch wire to cut out introducing the battery and lights to the gen for a load, and it miraculously regulated voltage fluctuating between 12-14 volts!!! Not sure how the cut out knows, or can tell that my new battery is 12v? Perhaps the previous owner mistakenly installed a 12v cut out on his 6v system?