Recommended · for some experience
Make your own Li-Ion Battery Pack
Why people recommend it
Suggested as a practical GreatScott guide to building a lithium-ion pack, including how a three-cell setup wires its protection board and balance leads.
Watch for: the build section starts around 4:30
In their words
See approximately 4:30 into the following video for the build instructions:
user1824797 on electronics.stackexchange.com, Jan 2023. CC BY-SA.