Need help understanding a circuit

[gyula]

Thanks to all for the explanations. I get it 100% now. It is almost the same as the SSG circuit but the pnp is missing. So this circuit is primarily used to send the radiant spike back to the source but unlike the SSG, the battery is fully disconnected from the rest of the circuit when it receives the spike?

Yes, I think this was the purpose of its designer.

Is there an advantage with this circuit when charging another battery instead of the source compared to the SSG circuit?

I have not compared them, sorry.

Gyula