My battery doesn´t want to power my laptop.

It sounds like one of the cells is dragging down the entire pack and you’re due for a replacement battery. You can find the battery here and the DP/N is 0JV6J. The guide can be found here.

If that’s too pricey for what I could immediately tell was a cheap laptop, there are aftermarket copies of the Dell battery out there for far less. Normally I don’t even mention this, but for yours I’m making an exception due to the cost relative to the low used resale value of these low end machines that are likely to contain eMMC. I still think it’s not a good idea for a good machine you paid a good amount for new, but I would get it if you put a knockoff in a cheap laptop like this where it was no more then $250, but between $150(Celeron)-200/250 (Pentium Quad).