From the symptoms, the battery is losing it’s charge, or, not being charged. This does not mean the alternator or battery are defective. The alternator may be producing the charge, but, because of poor electrical connections, power or ground, the full charge isn’t getting into the battery. Clean all wires and cable terminals, thoroughly.
Have the charging system checked out by a mechanic competent in electrical systems. Have the alternator output checked at higher engine rpms.