my car keeps killing new batteries. the battery warning light, the break light

Bad alternator or no power at alternator.

Have your charging system tested, most part stores will do this for free, maybe where you bought your battery. Maybe a parasitic draw test could be an answer.

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.