Sanyo UR18650FM Cell Specifications

[Korishan]

I had these cells charging at 1A for 7.5 hours and still not charged and very hot, no way I’m considering putting them in anything even if they do act normal the next charging cycle

That's because there's something wrong with those cells. Normal cells don't act like that.

 

[Oberfail]

I had these cells charging at 1A for 7.5 hours and still not charged and very hot, no way I’m considering putting them in anything even if they do act normal the next charging cycle

To add on Korishan's reply, those are called heaters.
If you set them aside for 2 days and charge them again, they dont heat anymore. However, they loose about 5% capacity per cycle and are therefor unuseable for anything more than 2-3 charg cycles.

 

[rev0]

Here's some more photos of the cell with clear side text marking "UR18650FM" (though a very faint imprint, easy to miss at a glance). These cells are "heaters" that I have (only reduces to <60mA below 4.1V in CV phase, otherwise will continue to draw >500mA turning it all to heat at 4.2V), I forget which type of pack I pulled them from, likely an HP or Lenovo battery. The blue ring color should be fairly accurate as taken from a high CRI LED light, but it appears slightly lighter/paler to my eye than the photo.

 

[harsha001by7]

I got Sanyo UR18650FM U27A with Dark Red wrap and Cyan Blue ring from Dell replacement battery. Any different specifications ?. Help me.