voltage across battery when charging ?

[Mustang_289]

We're running a stock crank pulley as once the motor is broken in, a Votech T-Trim awaiting our pony.

We put the grounding strap on - from the firewall screwed to the head on drivers side. We also put another alt. on the car and same low 12.3 volts. This clearly takes the alt out of the picture. We've also switched batteries as well no change.