I've had a similar issue, two separate times, fixed by alternator replacement and identifying parasitic drain. To test parasitic drain: With car cold/off for 30 minutes, set multimeter to 10-20 amps and remove your positive battery terminal from battery and complete the circuit with multimeter diodes. The voltage should show a number near 50-60 mA normally for passive systems. If the number is significantly higher, pull fuses one at a time until the mA drops <100 mA. Then you've found your culprit.