After WIN7 destroyed my battery (I know people say windows cant be blamed for this, but I still say its windows. How can it happen that a good working battery in October dies within 3 months? I ofcourse know batteries are getting worse if they get older, but within in from a pretty good battery to a really bad battery is not normal).
After that, I decided just to remove the WIN7 install I had, and to replac it with ubuntu. I already used ubuntu at several other PCs, and untill a few weeks I actually needed windows. But now, I dont actually need windows anymore, so I was able to replace my OS with ubuntu.
However, this didnt solve really my problem with the bad battery. The battery last with windows 20 minutes, and with Ubuntu around 30, so its a bit better, but still not much badly enough. So at that moment I had to decide what to do. I can just replace the laptop, or buy a new battery. A new battery isnt really cheap, its aroundd 100+ euro. However, a new laptop is more expensive, so in this case I decided a new laptop would fit better here. So now finally I have a decent battery again (This time one with 9 cells, instead the 6 cells the old one had.)