I spoke to my cousin in Dallas today who works in the electrical engineering division at Texas Instrument. He is actually like a jr. vice president there and designs a lot of contraptions like extended cell phone batteries and IC. He has a textbook on analog layout (see amazon.com under Roy Allen Hastings) he authored being used in universities through out and outside the USA. Since he seems to be rather knowledable in his field, I  ran by him what happened last night with the batteries and flashlight while at the light house in St. Augustine. He sent me an email stating the following so I wanted to pass it around since we all need to learn our equipment a bit better then we think we do. What I told him did not shock him one bit, and he has a very extremely scientific mind but no judgment on if ghosts exist. This is what he told me in a talk to the dummy fasion since he knows he speaks over everyone’s head using long words he knows the rest of the family doesn’t understand: 

"Glenn, Most modern batteries are capable of putting out more juice then you'd expect. Alkaline batteries, in particular, are designed to be able to put out remarkable amounts of power. If these batteries are shorted, they'll get very hot. This causes the liquid electrolyte inside to begin to boil, and the casings will swell or crack to relieve the pressure. This is a known problem with alkalines and with most rechargeable batteries. 

A lot of the flashlights are pretty cheaply built and it isn't at all inconceivable that one could short out. This would then lead to what you described. I believe that's what happened, and I'd suggest disposing of the offending flashlight. 

If you wanted to test a site for "battery draining" effects, I'd suggest buying a few fresh alkaline batteries and a battery tester. I'd test each battery to make sure they're good. Then I'd wrap the batteries up in waterproof, tamper-resistant packaging and leave them in likely spots for a month or so. Then I'd test them again. They should retain their charge; if they don't something funny is going on.

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In case know one knows, we had a flashlight get very hot to the touch after being used less then a minute. The batteries swelled up. As it was cooling down, I put my thermo scanner on it and it had a 129 degree F reading while Bart tried to extract the batteries out of the flashlight. While we thought this to be abnormal and related possibly to paranormal activity in the basement of the lighthouse, my cousin in Dallas had the above to say when I told him what happened and asked for his thoughts if something could cause a flashlight powered by two AA's to get hot and swell. His response was the above, so I am sharing it with all to benefit from his expertise so we might advance our own knowledge especially since we all use the batteries and experience power training. His advice may not be applicable to all sites we investigate, but in some places like our homes and offices it maybe worth trying out.