Car battery draining in an 88 Oldsmobile Delta, has new alternator on it

For whatever reason my battery keeps draining in
an 88 Oldsmobile Delta. The car has a new
alternator, battery, & the starter has been tested as
well. We put a disconnect on the battery as
suggested by my grandfather, but the battery still
drains when the car is shut off. When the car is
being driven the battery light stays on continuously,
& the battery dies within an hour of the car being
started, (even when it's been on charge all night
long) Any suggestions would be helpful, &
appreciated