Static battery should be around 12.5V, running 14.1-14.5V w/an ohm meter. Next, check your alternator w/said ohm meter. Put red wire lead on the output cable of alt and black on any body bolt (ground) or - side of the battery, it should be 14-14.5v of output. If you took it and had it load tested at AZ and it was bad then you have your answer. Could be a dead cell as someone else alluded to. Replace the battery and go on w/life. Not all-encompassing but batteries last maybe 5 years nowadays. I've found Walmart has the best warranty for batteries nationwide. Regarding squeaking noise, remove the belt and start the car (watch temp gauge) is noise present? No, you know it's rotational based in line w/belt...Idlers, tensions, pulley, etc. Now put the belt back on and start the car, now spray WD-40 on the pulley/idler/tensioners one by one to isolate sound until it stops. When it does, you've isolated said issue and can replace it as needed. If yes, it's the sound is internal to the engine.