CMOS battery

[tony6264]

This might sound stupid, but is is possible to cause problems by havung a cmos battery in backwards, that is, with the wrong polarity? I have noticed that certain tpads have the red and black wires opposite position on some models from others.

[Thane_Bitter]

YES!! I would say polarity is VERY important!! Just about every laptop CMOS battery that I have seen has a "keyed" connector to prevent getting inserted the wrong way (Desktop/Server mobo usually have a button cell - it's marked but you can physical install it in reverse). Often 3rd party batteries have separate connectors on each lead so that it will fit a variety of systems. Unfortunately if the PCB (printed circuit board) is not marked a person could easily plug them in the wrong way.
There are many different models of CMOS batteries, and not all ThinkPad’s use the same one.
Always check before making the connection.