david_prentice:
I answered that in #1.If you are doing a thesis, you can work out the resistors for a potential divider.
You can Google how to read your Arduino supply voltage with the ADC. e.g. to check that you have got 5V via the regulator from your Solar Array.
If you are not sure of something, post a schematic. A pencil drawing is fine.
David.
Hi david is my connection correct? is this gonna work? btw our 2.4 tft lcd is now working 
thank you for your help. Now im more concern with the program 
