I've used electrolytic rust removal for larger things like woodworking machinery. It does wonders for cleaning up cast iron. It only removes rust, good metal isn't harmed. Baking soda works, washing soda is a little better. You can leave parts in the solution for as long as you want with no damage. It also softens up old paint so it's easier to remove. I do find it's faster for me to wire wheel small items though.
You can build a tank as large as you need to. I've seen car bodies cleaned this way. I use an 18 gallon Rubbermaid tub for most of my stuff. I've also used a kiddy pool for larger items like my tablesaw cabinet.
Sometimes newer "smart" battery chargers don't want to work unless there is a battery in the circuit as well.
I bought a 12VDC power supply for running my tank.
The biggest downside is you have to occasionally clean the anode or replace it.
Here's a good explanation of the process:
http://wiki.vintagemachinery.org/Rus...ctrolysis.ashx
Rodney