If your cast iron pots or pans are getting rusty from collecting moisture this trick with a battery charger will help.
This electrolysis method with a manual battery charger works great on cast iron rust. Be sure to use washing soda, 1 tablespoon per gallon of water in your soaking container.
The battery charger must have a manual option and produce at least 6 Amps like this one or it will shut off and not work for this process.
Find Super Washing Soda here to mix in the water.