stereo light and battery problem help!!!

[NVERLAST1]

this is my issue. at night when i turn on my leds and play my radio when im stick in traffic lights cut off. i have heard the alternator doesnt work under 3000rpm but would it help if i got a better battery? I have the agm battery from batteries plus. i was hoping the odyssey or motobatt would help me out.

[coz]

have u checked your cable connections on the battery? clean and tight? are u using a big amp on your stereo? are there a ton of lights? need more info.