vehicle voltage

I was wondering how low the voltage can drop with the car running for the battery to still be charged and not be used to power things. I am asking the question because I have two polk audio amps and with the ac at full blast, the voltage drops to 12.8 sometimes. How low can it go?

Not that low... A lead-acid battery requires 2.4v per cell (2.4*6=14.4v) to actually CHARGE, to maintain the charge, requires 2.25v per cell (2.25*6=13.5v) This information was gathered here... Other good information there, also! You need a larger alternator. Period.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Wow that sucks. My car is leased so i didn't want to start messing around in the engine bay. The audio components can be just taken out at the end of the lease pretty easily but the alternator is more work. How much do you think it would cost to get a ho alternator installed. I would be getting it online so I am only asking about installation costs. Also what kind of shop would install it? Would I go to a regular vehicle repair shop or a car audio place? I was also worried about voiding the warranty. What do you guys think?