I am not sure what's with the tone of this comment, it seems a lot like a teacher who once told me I'd never be able to get a job if I put my feet on my desk, but, here I am.
(26) Baggage equipped with lithium battery(ies) must be carried as carry-on baggage unless the battery(ies) is removed from the baggage. Removed battery(ies) must be carried in accordance with the provision for spare batteries prescribed in paragraph (a)(18) of this section. The provisions of this paragraph do not apply to baggage equipped with lithium batteries not exceeding:
(i) For lithium metal batteries, a lithium content of 0.3 grams; or
(ii) For lithium ion batteries, a Watt-hour rating of 2.7 Wh.
https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/s...