Hi
Thanks ...
It works ,I am using 10k/1k and the voltage reading is the same when using the usb 4,5v or the external Vin 4.95v.(12Vbattery)
Never thought that a to high input resistance will have a affect on power source used 4.5v or 4.96v.
I dont think noise was a problem I am using a 12V battery,the readings was stable.
Yes I did learn something.