New laptop battery charging only until 37% and keeping alive after reaching 0%

I just bought a new battery for my laptop (Sony VAIO). When I plugged it the first time it was 66% charged. I use it until I reached 5% and after that I started charging it. It just got charged until 46%, after one or two more iterations of the same process, it only charges now until 37%.

The funny thing is that when it reaches 0%, I am able to use the battery like half an hour more. Is like the charging values have been shifted (from 100% to 37% and from 0% to negative value) weird isn't it?

Has anybody seen this behavior before that can make some suggestion on how fix it?

Thanks in advance.