battery drains overnight. batteries charged - engine stops when you take positive cable off

It sounds like a bad battery or a bad battery and alternator. I would change the battery to see if that fixes the issue. If that does I would still test the alternator to make sure it is working properly so you don't drain and kill your new battery. This happened to my vehicle where my battery just could not hold a charge no matter how much I charged it. It was draining so badly that even after I would jump it if I turn on any lights it would draw more power than the alternator could provide and just die while the car was running and kill the car. Once I changed the battery out and tested the alternator to make sure it was still working, my car started working fine and has worked like a charm ever since. Remember most batteries come with a warranty so save the receipt when you get a new battery and make sure you get the correct one since there are several different types.

don't remove batt cable with vehicle running you may have fried something , even when car is off a memory saver should be used on newer vehicles , don't make a new alt. charge a low batt.