I've just been exploring aimlessly and I feel like I'll need them

:0)

So do you trade zonai charges for energy cells?

AND I FOUND A PIRATE SHIP! :0)

you use the wells after getting 100 crystals (sorry if this spoils stuff)

You need to find a forge construct to get crystallized charges by buying it with zonite then trade 100 for an energy cell

Go to the last shrine on the great sky island. Around that area is a construct that will trade crystallized zonite for energy cells

you need to get 100 zonite and trade with a forge construct for one, also the large zonites count for 20

there is a zonai construct right next to lookout landing who will trade crystalllized charges for an energy cell. it is literally five feet from the north exit, but it is on top of one of those big rocks that fell from the sky so it is easy to miss.

Does it still cost 100 of them?

yes

Great. (Sarcastic)