Wondering if it would be possible to rebuild a pack using these: US $16.5 45% OFF|3.7V polymer lithium battery 855090P805090P mobile power large capacity lithium battery MID package post Rechargeable Li ion Cel|polymer lithium battery|3.7v polymer3.7v lithium polymer battery - AliExpress
As near as I can tell, they are the right physical size.
As near as I can tell, they are the right physical size.