Actually 2 Datel X2 would do + your original psp battery
Rated at 3.6V and 3600mAh, this Lithium polymer PSP add-on claims it will double the battery life of Sonys much delayed, yet wonderful portable. This makes sense given the PSPs battery at 1800mAh is exactly half that of the Datel product and means owners could potentially get seven hours of gaming off a single charge.
do you really need the battery to last the whole flight ? i'm off to oz in 2 weeks , i'm taking my psp but i don't plan on using it the whole flight !!!! don't know about you but i'm flying emirates and the inflight entertainment consists of about a 100 movies/tv shows etc etc.... plenty to keep me going !!! the flight is such a nightmare , anything to make it go faster !!! i may look at getting one of these datel max 2 batteries though !!!!