We have design for using a battery socket with a 2.6Ah 18650 format cell. Unfortunately, the 18650 batteries can be reversed in socket (that is + instead of -). The problem is that some cylindrical batteries do have internal protections, others (especially ultra low cost, un-branded) don't.
So the customer can insert battery in wrong polarity and more dangerous, potentially can use a no-name battery without any kind of protection.
Our idea is to use a fuse in series with battery (glass, smd, 30mR) and a reverse polarized diode in parallel with battery in such way that if normal connection, nothing happens. Will be a little voltage loss across fuse so no more 4V2 when charging with high currents. In case of wrong polarity, fuse will blow which will make the module out of service. PPTCs have much more resistance and moreover, resistance will increase with trips.
MPS2637 is internally protected to reverse battery?
Other ides for protecting in such situations?