autometer reading is off

[newbe60]

have a 68 camaro with an ls2 and paddle shifters.. so there are two computers for the car (one for the ls2 and another for the 4l65e to work the auto trannny... at the battery it's reading 12.9 with the key out.. and at the battery it's reading 14.0 with the car started and at idle.. problem is i have two meters inside the car an autometer that reads 12.4 at idle and while i drive and the paddle shifter control is reading 12.2 at idle and while i drive it.. any idea's why? should i worry about it.. how can both be off?

[Twentyover]

Are they pulling power from the battery terminal? When electricity moves through a wire harness,the current flow rate and wire size will cause a voltage drop.

[hifi875]

Make sure you have a sufficient size charging wire from your alt to your battery. other than that ^^^^^what he said