Problem with battery and car brain

Hello, i hope you can help me out with my renault megane 1.6 atm gearbox year 1996. The problem started when i realised that the battery is emty and bought a new one and one day later it was empty as well. I allready tryd to see does the generator works and charges the battery and it did, and now i have no idea what is the problem.. last time i was driving and in one moment it gave me the car brain icon on the dashboard and the motor died on me.. when i recharged the battery was everything back to normal untill the battery died again amd the same thing happend again. Maybe somebody can help me please.. i like this car tooo much