
Onn Powerbank model ONB14W1201, $2 clearance buy, but handy and functional. Reading a bunch last night about Li-ion chargers, I had a sudden urge to look inside.

..roundness? This looks so much like a plain standard cell, or one of those half-length ones.

It’s a plain ol’ 18650 Li-ion cell with a little driver! The white parts pop apart down the other side, btw..

Looks like standard ICs and they left the numbers on. I’ll look into it more later, but these look like what I bumped into constantly hunting obscure Shenzen parts no one has sheets for.
It’s spot welded in (as internal batteries or individual cells usually are – the strips are often zink plated stainless to handle the heat changes. But it could probably be modified to charge 18650 (probably the most common Li-ion cell around and the basis for most “normal” high power rechargables) or to recharge your phone with infinite 2000-2300 mAh chunks for a few bucks a cell. Possibly even expanded with a few in parallel but that might get adventurous current wise. Will have to see what the ICs claim to be.