Battery drops from 100 normally, when reaching 90 it shutsdown and says it's 0

[Android Central Question]

I don't know if I need to buy a new battery and get it replaced as I have an S6 let me know what you guys think I can do to fix it.

 

[Mooncatt]

Is this something that happened all at once, or was it gradual over time (I.e. Shut off at 20%, then 30%, 40% etc)? If it was gradual, I'd say replace the battery. If it went from zero symptoms to shutting off at 90%, it may still be the battery but that would be an odd symptom pattern unless it has an internal short (which I've had happen on one of mine, and would get very hot in the process).

 

[Rukbat]

It sounds to me like a dendrite (Lithium Battery Dendrite links). That would mean a replacement battery.