How do you stop the battery from dying over the weekend on a 1987 Cadillac Seville?
Remove the negative battery cable from the battery negative terminal and set it aside so that it cannot make contact with the terminal. Just make sure you are not laying it on another piece of metal. It can be tied in position with a piece of string. You can "insulate" the cable clamp by wrapping a rag around it, which will prevent contact if the cable should shift back against the negative terminal. Or, buy a battery disconnect [switch] from a parts place, and then all you need to do is turn the switch and the battery is no longer connected to the car's system. Answer 1 assumes that the problem is some kind of electrical drain in the vehicle electrical system. The problem could could be a battery nearing the end of its life, and simply is not capable of holding a charge. j3h.
A little known problem that exists is that the vehicle's blower control system (in the front dash) has a speed regulator called an ATTENUATOR which controls the speed at which the blower blows. For example; most cars have High, Medium and Low for blower settings whereas, Cadillac's have a 0-100 speed. Meaning, you can set this speed anywhere on that grid and the blower will stay at that level.
The ATTENUATOR unit is located inside the dash controls where you adjust the blower and it's tough to replace. However, if not done right after the attenuation system burns out the burned system will be left to it's own devices which equals a constant drain on the battery. Why? I'm not sure. But I do know once the part has been replaced the problem is fixed. I believe it has something to do with the in-line fuse assembly that it 'BLOWS OUT' at the same time. Without a fuse, the power will drain through the wiring harness until the battery is dead as dead can be. I found it lasted about 30-45 minutes after each charge. So, that is a very quick drain on any battery.