Asus 1225b, turn off(not shutdown) randomly. When unplugged whereas on AC it works fine. Anyone?

[TwoPoint Zero]

Asus 1225b, turn off(not shutdown) randomly. When unplugged whereas on AC it works fine. Anyone?

 

[Rice Wine]

I have a different laptop, but the same problem, I suspect it is the battery not being able to provide enough energy. Replacing the battery fixed it for me.