Officially from sony batteries the max. capacity for the psp slim its 2200mah , the new ones comes with new Back cover to fit in the slim , there are more batteries for the psp slim or fat like the 3600 mah you mentioned but most of them are crap they die faster than your slim battery.

i havent test the 2200 mah battery in my slim yet , but i heard it doubles the battery time of the slim.

MKoWnZ its easy just press the buttons on the totem pole wait to the pole to jump then press the buttons again and so till it gets out of the ground he will leave the compass that will reveal a hidden ruins i think, just wait to the pole jumps and then play the drums .