PMSL you must be pissed Rich
How are you gonna split Hydrogen and Oxygen from the water with just a battery. Don't know if you can remember but prob at school they showed you electrolysis, and it would show tiny bubbles of Hydrogen and Oxygen on either terminals.
You would need a lot of Hydrogen, which means a lot of power to get that Hydrogen.
The engine would always consume far more Hydrogen than what could be produced. Even if it didnt, the engine would have to power the alternator to split the water. You don't get power for free, due to energy conservation so it would never run.