In the light of interesting things happening with the sega hardware happening recently I did a bit of a google regarding Nomad battery life and found an interesting post
http://bibin.gg8.se/blog/projects-and-g tery-life/
The basic idea seems to be to replace the nomads original lighting system with one which uses about 1/10th of the power ergo in theory increasing the battery life. The page isnt particularly detailed (no disrespect to the modder!) so I wondered if anyone can confirm this works or provide any more details?