yes, and typically at the very least a protection circuit that needs to be implemented or faked, or whatever. i replaced a swollen battery on a cheapo hotspot

yes, and typically at the very least a protection circuit that needs to be implemented or faked, or whatever. i replaced a swollen battery on a cheapo hotspot with an 18650, but i had to remove the protection chip from the old battery and wire that up with my battery holder. if i was more industrious/desperate i probably could have used the one in the 18650, but that was more fiddling than i wanted