Looked into selling my old gaming laptop just recently, and it just doesn't seem like its worth selling them, if they are any older than 5 years, and not top spec.
Making a server/node/test machine, might be the best option. Still not comfortable with the laptop battery as ups thing.
Still not comfortable with the laptop battery as ups thing.
You probably already looked into it, but just in case:
Depending on the model of the laptop, the battery might be removable using simple tools and without having to deal with adhesives.