Basically iron nails and copper wire combo on a sink plunger.
http://www.instructables.com/id/Make-a-Powerful-9V-Rechargable-Battery-From-Nails/
Basically iron nails and copper wire combo on a sink plunger.
http://www.instructables.com/id/Make-a-Powerful-9V-Rechargable-Battery-From-Nails/