[twobjshelbys]

Just try a new battery. Pull one from another vehicle and just connect it up to see if it starts. Don't need to be perfect fit just to test. If another battery works just get a new battery.

Parasites do exist. If you don't put in a full cutoff switch (my Cobra had one, in my case the parasite was the Fuel Injection Controller) then use a battery tender on it while it is parked.