Overnight the battery drains

You will have to do a currant draw down test. Remove the battery positive terminal and connect one end to a multi meter cable positive (+) and the other cable from the meter to battery negative (-) set meter to amps and with key off and all doors closed see what the draw down is, (you may have to wait about fifteen minutes just in case any module need to power down and go to sleep). If you have any dray greater than around.15 Amps ( this will be fairly normal back ground current dray for memories in radios, clocks and modules) start pulling fuses to locate the circuit that is drawing current. If the meter drops down to a normal reading this will be the problem circuit to investigate. Also, drop off the alternator main wire as a test as a blown diode can cause problems and still give you a low charge rate that can often be overlooked.