That's awesome. Thanks for the time and effort you took to experiment and refine the process, it makes me wish I had something rusty (and a battery charger) to try this with. Maybe I'll have to try it with an old computer power supply.

I think your observations/theories on the anode are probably correct, a more uniform current density certainly wouldn't hurt anything and rinsing the sponge and resoaking it with fresh electrolyte will eventually be necessary.