Battery keeps running down

What could be drawing my battery down? After leaving my car unused for several days or longer when I turn the key in the ignition all I get is dead silence yet it boosts easily and instantly. I have replaced the generator and two batterys

What’s the battery voltage with the engine running?

Check if any of the interior lights (glove compartment, underhood, ashtray, etc.) are staying on with the doors shut.

How old is the battery? Have you had the batter and charging system checked. Many auto part stores will do it for free. Any CEL’s (Check Engine Lights?) If you can’t get to the auto parts store, the voltage check is almost as good.

OK likely you did not find it with the above, but it is good to get those out of the way. You need to find out what is pulling more than design power with the car off. You need a fairly sensitive amp meter and a little time. You want to hook it up and watch it for like 5 minutes to an hour. Report back please.