The Precise character card says it can't be charged by a rest action and doesn't give any other way to charge it - does that mean when the starting charges are gone the card can't be used again other than counting as a Tech?
It is hard to charge Precise Internal Clock, but not impossible. Things that can charge Precise Internal Clock are:
* The Scientists
* Cavernous Hive Mind Computer
* Conjunctive Astral Harmonizer
* Energy Transference Inducer
* Obsidian Amulet (This one is really good)
I know it seems severe, but each time you use Precise Internal Clock you functionally gain an extra countdown clock step. If you could charge it too easily, it would be a game-breaker.