Got a Screen : 7 inch. resolution: 1280*800, brightness rating max 1200 nit (cd/m2) . very bright. enough for ourdoor.
the Screen tested result:
brightness 100% 1.26A @ 11.25V 14.2W ;
brightness 50% 0.87A @ 11.25V 9.7W ;
brightness 30% 0.72A @ 11.25V 8.1W ;
Power Supply I will need :
Lipo Batteries s 18650 9pc, 3s3p to make 11.1V
A voltage regulator to 5V output for the Raspberry Pi
3S Lipo Charge/Protection Board
others: wireless KeyBoard/Mouse
I think this setup can hold up to 6 hours.