This thread left me with mixed emotions, namely crying & laughing. Can't believe anyone would even consider dumping a battery in the water when it is a well-known fact there are much better, heavier things to use. I like to save up all my old thermometers and break open the glass, collect the mercury until I have enuf to fill one of those 15 gal
herbicide drums with that are so easy to get from farmers. This works perfect.
The old rods from a nuclear reactor are good too if you can get a word in when they are tearing down an old nuclear power plant, and have the unique quality of being able to locate yur brushpile with a geigercounter.