beeping sounds from inside - any ideas?

So, for a month or so my battery icon comes on when engine is off and radio is on. I would assume I need a new battery which I will be replacing in a couple of days. The last couple of days I heard some beeping sounds from the inside. It goes "beep...beep...beeeep" and thats it. It happend twice now. Has anyone here experienced this before? Is this related to my battery gonig bad? Any help would be great. Thank you guys so much.