Depending on the
version, this Poly-800 may not have an internal battery at all. It would be on
the CPU board between IC18 and IC19 if it has one. If it is really old, this
will be just empty space. If it is a bit newer, it may have solder tabs where
the battery would eventually go, but no battery. The last ones manufactured just
before the Poly-800 II actually had a CR2032 lithium cell soldered in there. I
this is one of the earlier two types, it would need some small modifications to
the power circuit to safely install a CR2032
Don
B.