I am confused what the component is that a series hybrid power train uses to convert the ice energy into the electricity to charge the batteries, I’m assuming you need more than just the stock alternator that comes on a motor. Do people just use the ice shaft to turn an electric motor or is there some larger alternator that some people use? Every diagram I have ever seen online just calls it a “generator”, what do people usually use?
Are you trying to build a series hybrid on base of an existing car? This is a difficult proposition: looking at sourcing a generator to attach to car engine also means you kinda got lost and not seeing trees for the forest.
What you need will strongly depend on what your end goal is ultimately. Given how pricey EV conversions are in general, it’s almost certain that you could get there much faster and cheaper by just buying one of the used series hybrids already in the market.