Samsung s6 edge battery drains super fast at 15% My battery lasts normally during the day however I am observing a weird issue where when my phone reaches 15% battery warning. It discharges in few minutes which to me is counter intuitive. 

I had phone for about a year. I normally last working day without needing to recharge with 50% left. But sometimes if I am using phone a lot it drops to less. I think problem is not with battery but rather with it discharging really fast after warning. It's as if some mechanism starts using more battery after the warning.

I haven't reset phone since I bought it. I don't frequently get to 15% level though, only noticed this behavior recently, and had phone for a while.

I use normal charging mode and not 'fast charging'.

UPDATE: I had a theory that it's 'power saving' mode that was causing this so I changed setting to switch to it at 5% from previous 15% then drained battery and observed and it didn't matter - once battery got to 15% it discharged to 7% in ~3 minutes.

I am sure it's happening to others, why does it discharge so fast? How do I fix it?
This was occurring for me as well, and a resolution was reached, although it may not be valid for everyone.

It is the sign of a failing battery, and is unfortunately common in the S6 series. Once the phone goes into Power Saving Mode, it seemed like the battery would drain abnormally fast, sometimes skipping from 15% to 12% immediately. 

My carrier (Verizon) claimed that it is indeed a bad battery, and they are aware of the issue. Samsung typically wants you to send your device to them for repair, as removing the case and battery yourself will void any remaining warranty. Thankfully (hah), my device also had a faulty camera, which was close to failing entirely, and Verizon was able to replace my device with a brand new one (not a refurb, which I was surprised at). It was still under a manufacturer's warranty, so I did not have to pay for the replacement. 

Regardless, get in contact with your carrier or Samsung, and see what they can do for you. This is unfortunately the only solution that worked for me. All the tweaks and tips from various Android sites were unsuccessful in helping the battery drain.