I purchased the new iJoy Captain box mod 2 weeks ago, and quickly discovered the 20700 battery cells did not fit in my old Nitecore I2 charger - bay is too short.
The “NEW” Nitecore I2 and I4 chargers DO natively fit the 20700 cells (and larger), and I grabbed an I4. Working perfectly.
Testing on an Efest LUC V4 at work I found they barely fit but scraped against the contacts and was likely to damage the wrap if not the cell itself - I’d strongly advise against using it, or squeezing them into any other bay only meant for the 650mm length.
Have read of some new XTAR models being compatible with the 700mm length as well.