Is fast charging actually killing the battery? What's the best way to charge your phone? Will battery degradation make your phone lag or slow down? At what p...

TLDW; No

Basically the video is testing phones with varying charging speeds and how much battery degrades after 500 charging cycles. Also, the affects on performance after battery degradation at 5:37

Timestamps of some tests:

  • Test results for different charging speeds at 3:06
  • Storing batteries at 1%, 50%, 100% at 3:43
  • Battery performance at 4:42

After 6 mins he talks about why the tests took 2yrs and how they did it 3 times.