If there are smoke and fumes present on the flight deck, most likely the source is there as well. The battery is a long ways back in the aft EE compartment, so smelling it on the flight deck is unlikely.
APU battery is in the aft EE compartment. The Main Aircraft battery is a lot further forward. (I think the forward EE Compartment)
Apparently the batteries are supplied (manufactured) by a Japanese company. Oh the irony.
