Glen Wiley wrote...

>After some reading, I have just learned how a voltage divider works
>and I would appreciate feedback on this if I have it wrong:
>
>Vout = Vin * (R1 / R1 + R2)

That's not correct for the circuit as you've drawn it.

The voltage divider's output voltage will be

Vout = Vin * R2 / (R1 + R2)

If you're operating off a regulated 5V supply, you can just set
up the A/D converter to use Vcc/Gnd as its reference and make
R1 = R2 = 10K ohms.  That way, the A/D result will represent 10
volts full scale, or 0.01 volt per count (within a few percent).
Nice, convenient scaling.

>Where
>        Vout is max 5V (connected to AN0)
>        Vin  is the battery voltage
>
> bat+ ---|
>         |
>         <
>      R1 >
>         <
>         |
>         |---- AN0
>         |
>         <
>      R2 >
>         <
>         |
> bat- ---|
>
>If Vin is 7.2V and R1=10K then R2=4.4K

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