I know I've asked quite a bit of questions however, I was wondering about how much power a portable Wii would consume with a 5 inch (diagonally) screen with everything else usually in a portable like a Wii and fan etc.
It depends on a few different factors. If you use a four layer Wii, with 4 3500mAh-ish 18650 batteries, and a Wii PMS you can expect to get 4 hours of battery life on Wii games and upwards of 5 on GameCube games.