I have encountered the same problem several times before. If my phone (s9) is doesn't have very high battery before work I'll switch it to ultra power saving mode in case I need it since I cannot use it while working. Every single time I turn ultra power saving mode off the battery drains within five minutes. I just tested it and within 2 minutes it went down from 8 percent to dead. This has happened every time I needed to extend my battery so has anyone else experienced similar problems? Anyone have any solutions?