charge up vs weaken

charge up

verb
  • To recharge, to give electrical power to something. 

  • To deliberately infect an individual with HIV as part of bug-chasing. 

  • To motivate, to instill someone with determination. 

weaken

verb
  • To make weaker or less strong. 

  • To become weaker or less strong. 

How often have the words charge up and weaken occurred in a corpus of books? (source: Google Ngram Viewer )