Probier mal das hier, bei mir funzt das absolut genau.

Dim Volt As Single
Dim Cap As Single
Dim Caps As String * 3
Dim Volts As String * 4

Do
C2 = Getadc(2)
Volt = C2
Volt = Volt / 73.75
Volts = Str(volt)
Volts = Left(volts , 4)
Locate 1 , 11
Lcd Volts ; " V"
Cap = Volt - 6.7
Cap = Cap / 6.3
Cap = Cap * 100
Caps = Str(cap)
Caps = Left(caps , 2)
Locate 2 , 13
Lcd Caps ; " %"
Loop

Viel Spass damit
Gruss Clemens