You will need a manual battery charger for your electrolysis tank. I like the chargers with a manual/auto switch.
An auto charger can't charge a completely discharged battery. I think the battery needs to be at about 4 volts (on a 12v battery) before an automatic charger works.
If I have a really dead battery I have to charge it in manual mode for awhile to bring it up to the point where an auto charge will begin working.
