Bring 90 orbs to your Uncle is a mission in The Precursor Legacy that Jak and Daxter complete to earn a power cell. The Explorer in Sandover Village asks Jak for ninety Precursor orbs in exchange for a power cell so that he can set out for his journey. He claimed to have previously had the orbs, but surmised that Daxter stole them for fun.
Although this mission is assigned in Sandover Village, the Precursor orbs can be collected from any location, and talking to the Explorer prior to collecting them is optional. Upon collecting at least ninety orbs, return to the Explorer's hut, which is the second on the right after crossing the bridge from Samos' hut.