Battery volts now is:12.7 and @ A1 stands at 2.681

Maybe I've got defective resistors, those are quite hard to get here where I live, I will try to get new ones today.

Depends on the tolerance of those resistors.

At

1%:

R# | Nom | Low | High |

R6 | 82k0 | *81k2* | *82k8* |

R7 | 20k0 | *19k8* | *20k2* |

The formula for calculating the

A1 voltage [the voltage across the 20k resistor], if we call the 82k resistor

R6, and the 20k resistor

R7, and the Battery Voltage

V_{B}:

V_{A1} =

V_{B}R7/(

R6 +

R7)

And to get the Highest voltage possible, due to tolerance variation, we take the lowest possible resistance for R6 and the highest resistance for R7, like this:

V_{A1(max)} =

12.7(

20.2)/(

81.2 +

20.2) =

2.53VWhich is lower than your measured value of

2.681VBUTLet's say your resistors are

5%. Then it would go like this:

R# | Nom | Low | High |

R6 | 82k0 | *77k9* | *86k1* |

R7 | 20k0 | *19k0* | *21k0* |

V_{A1(max)} =

12.7(

21.0)/(

77.9 +

21.0) =

2.70VWhich

*is* greater than

2.681V, so definitely in the

*valid range*.

Which means,

not *defective*. But, merely a case of

*insufficient precision*.