Thanks for your reply
I will be dismantling my laptop once I get a new battery, but problem is I don't have anywhere here I can leave it 'opened up', dustfree.. so then I would have to disassemble and reassemble twice, which idno, once is already enough of a hassle for me (quite new to it).
People on other forums have been saying it's probably a 3v CR 2032, but I can't be sure of course. I attached a picture a guy from the Belgian Asus TSD sent me showing me the location of the CMOS battery and that it's not soldered onto the motherboard. I do have a disassembly guide for the N61VN, which should also work for my model.
Here's a link to my initial thread about the problem, btw: Asus n61Ja bios update problem