Mid 14s is a healthy alternator with good connections. You don't have that, and neither does the OP. Something is wrong with both of your charging systems.
Retros, LEDs, SD Hood GMPP, Votland, Addco
06+ Impala brakes, L76 Springs, ERs, Self-Tuned, 3.5 Gen V L32, Ported TB, 240a CS144, SSAC, Upgraded Transmission, Android Head Unit, Remote stuff, GXP Seats