XPS 13 9360 does not charge

Hello,

For several weeks now my xps 13 9360 (that I bought 2 years ago) doesn't completely recharge to 100%. It doesn't even charge at all these last few days. In a first place, when I connect the power cable to my pc, it's indicating me the pc is actually in charge : the indicator light below the touchpad is turned on and the desktop icon on the bottom right is on. But this only lasts a few seconds, until the indicator light and the desktop icon turn off. Sometimes the charging is done but in a eratic way, alternating charging/not charging periods.

This eratic charging issue became worse day after day. At least before I could charge the laptop for 1 or 2 hours, even if I still couldn't reach 100%. But then the charging periods decreased rapidly, and now I'm finding myself disconnecting and reconnecting the power cable all the time. 

I don't think this deals with the power cable because the indicator light is on. So there is still power in it. Is it the battery ?

Thanks in advance