Building a "Baghdad Battery"

Step 3 Constructing the Electrode Pairs

When testing most cells, just a wrap of rubber tape around the two electrodes is all that is needed, but since this cell is based on a set of artifacts, we want to emulate the dimensions and geometries as closely as possible. Instead of asphalt for the sealant - seen in the artifacts - I used rubber tape. I tried asphalt, but it is messy to work with and clean up, and you have to wait for it to set - when working with several cells at once, it becomes a headache.

The photos should be more explanatory, but roughly:

• Drill a hole in the mason jar lid and slide the Fe3O4 coated iron nail through it
• Drill a hole in the rubber stopper so the Fe3O4 coated iron nail can fit snugly through it with the head of the nail protruding an inch or so from the top - you may want to put a single wrap of rubber tape around the upper exposed portion of where the nail interfaces with the stopper to seal it
• Form a piece of copper sheet into a cylinder around the rubber stopper so there is a slight opening (as seen in photos) still visible along the side, now wrap the top portion with rubber tape and attach the stranded wire to the side of the copper and then wrap again to seal the copper against the stopper, also put a single wrap of tape at the bottom to help hold the slotted cylindrical form
• now, slide the wire through the hole drilled in the jar lid and put a wrap of rubber tape to secure the wire to the nail at the point where you would like to interface with the mason jar lid, force the lid down on to this wrap of rubber tape and you should have a tight seal - it should look like photo 1
• now, fill your mason jar with 20% KOH or other alkaline electrolyte and place the mason jar lid assembly you just created into the solution and seal the jar - it should look like photo 3

If you just want to evaluate the chemistry and don't need a full scale replica of the electrodes, use reduced dimensions and one of the simpler construction options I outline in the next step. Instead of a slotted copper cylinder and a large nail suspended down the center, the electrodes can be simplified to a strip of copper and iron.