Extreme power consumption, like a short! Not a safe situation. If you have a meter, check the current flow through the cables. To find out where the power is going, pull ALL the fuses (noting where they went) and then with your meter, replace them one at a time.
A raidator in need of a flush will not cause a battery drain.
check your battery cables loose or dirty cables will cause this. if the problem persists check the reg/rectifier
A short in the wiring.
Dead battery? Battery cables in need of cleaning or replacement?
Dead battery? Loose or corroded battery cables? Blown fusable link?
Shorted diodes in the alternator.
Battery or battery cables would be the first thing I would look at.Battery or battery cables would be the first thing I would look at.
Weak battery? Loose or corroded battery cables? Starter solenoid?
Possible cause is the crankshaft position sensor if you have a bad alternator then your battery can drain while the car is running DOn't know when did you changed cables lately but arching on one of them will do that. Check the cables for any damage or wear. Also look at distributor while you're there.
dead cell in the battery or something is on pulling power from the battery.
Your alternator could be bad.
Any relay could be the cause.