, heres my findings related to power consumption and what not.
The wii power supply is rated to 3.7 amps, the wii itself is rate to 3 amps.
The wii requires 12 volts. The wii power supply normally outputs around 12.2-12.3 volts)
The wii actually draws 1.2 amps average and upto 1.7-1.8 peak.
The highest voltage i have used the wii at is 13 volts. (Probably could go a bit higher but i dont want to risk it).
The wii will power on at the lowest of 12.1 volts but if powered on will go as low as 9.3 volts before it stops working.
with a rather old 2.1 AH sla battery i got 50 mins over all and 40 mins hard gameplay on cod 5 WAW with an audio amp, extra fan and usb keyboard running from the usb power rail.
Happy hackings