Where is the cmos battery?

I have a liquid damaged 2007 macbook 2.1 GHZ (A1181) that's working fine but isn't charging the battery.

I swapped out the DC in board and battery connector with known working parts but the issue remains.

I tried an SMC reset several times but to no avail.

I decided to disassemble it to clean up the logic board (there was some corrosion on some areas) but when I took it out and turned it round to remove the cmos battery there wasn't one. I assumed it was removed and not replaced as the macbook had clearly been opened before, but I couldn't find the jack for it.

Here's the type of logic board: http://www.techex.biz/ebaybiz/pics/Mothe...

This is the one I've seen before, where the cmos battery is placed in the middle of the board:

http://67.19.154.220/HQ/apple_macbook_a1...

Where is the cmos battery to be connected on this logic board?