Hi-Power Polymer Li-Ion Battery Pack for Airsoft Gun: 11.1V 4000 mAh from Batteryspace. Will the 12v input on the psu accept 11.1v? or will I have to use a nasty step-up? Will it accept 14v?
According to ER's readings, the GC itself uses about 8.5w. LED modded PSone screen uses about 3-4w (depending on how efficient your regulator is). Thats about 12w total. That battery is about 44wh, so you'll get at least 3, maybe 4, hours of play.
Maybe one of batteryspaces other chargers will work, they're only ~$30. You might want to spend the extra though, the expensive chargers balance the cells, which should help the pack last longer.