I recently sold my business and bought home the laptop for my boy to use/have.
I knew the battery was shot but thought I'd have a fiddle with it before buying another one.
Well, I totally failed to fix the battery but after I'd cracked it open I thought 'those batteries look familiar'.
I tested them and the voltage came out fine, they were 18650 batteries. Now I don't know if they are the protected type but I can tell you that they work in my Dereelight.
The battery is from a Toshiba Satellite M40 the same as this one and can often be bought from ebay for a fiver. The same as this one
Crack it open and get 8x batteries for a fiver