24v HHO system for a diesel power generator

[afjsph]

hi
am making an electrolyser for a power generator for a friend of mine. the battery supply is 24v. is my design of +NNNNNNNNNN- correct? is should give a voltage of 2.18 between plates

the second question is in the electricals. since the power generator is unmanned i dont want to connect it to the ignition switch since sometimes the generator cuts off on its own and could be a while before someone attends to it. the idea is to power it only after the engine starts so if the engine cuts off the hho system cuts off too. i was thinking of connecting it to the wire that goes from the alternator and charges the battery.

does the alternator at some point stop sending power to the battery when it is fully charged thereby stopping power to the hho system? is there any other connection i can give so that the system will only power once the engine is firing and stops when it is not