DELL XPS 9550 battery runs out instantly under loads

Hello, I'm a Dell XPS 15 9550 user since last year.
When i'm using it on battery power, even when it's 100% charged, and I decide to use some medium-work applications like Lightroom, Photoshop or even worse Premiere, my computer instanty turns off, as if the battery ran out. Indeed when I try to turn it on it keeps telling me that the battery is out (usually it is right at 1% or even 0%) but the funny thing is that after turning it back on I can use it right away without any other intermission or problem! I can even use those heavy power application that sent it to sleep a second before! It's like the computer can't recognize how much battery percentage I have, even if it's full.

Obviously, my premium support is expired.
Any help is appreciated, thank you!