Does anyone know where the internal battery is?

My z7 is not remembering date etc, so think the internal battery might need changing. I have tried to charge it as the manual states by giving it power for 24hrs, but no luck.

They hide it pretty well and it's a job for a service tech. On some models it's hidden in the upper handle or behind where the lcd screen flips out. Usually on the main circuit board.

Yep, the batt is BT7001 Lithium, on the ZZ-005 complete board, hidden forward, below the handle, under the built-in mic. You have to disassemble the whole handle assembly to get to it. If you are mechanically inclined, the Frank's HDV site has all the service manuals you can DL. Should be a permalink at the top of the Sony forum here.