On 1/10/2017 9:42 PM, Peabody wrote:
The standard instructions for changing out a desktop CMOS battery say you
should turn everything off and unplug the power cord. But I wonder if guys
who do this kind of stuff for a living don't hot swap the batteries with the
power on, or at least leave the power cord plugged in so the always-on 5V
supply provide power to the CMOS. That should prevent losing the contents of
the CMOS memory, including the TOD and the BIOS settings.

On a related question, I also have an old Toshiba Satellite L35 laptop that
I'd like to replace the CMOS battery on. It looks like I would have to take
the entire laptop apart so I can remove the motherboard, turn it over, and
replace the battery. Or, it turns out I can see the battery through the side
of the wireless compartment, and I should be able the cut a window in the
bottom of the case through which I could switch out the battery, then hot-
glue the window back in place. Is there any reason not to do it that way?
It's a lot more likely the laptop would survive the latter procedure.


Problem with doing anything with the power on is the unexpected.
Suggest you at least put some tape on the battery so you have
something to hold onto while you try to pry it out.

The other issue is the reset. Assuming you have a reason/symptom
to change the battery, it may be that the state of the memory is
compromised. I've had laptops with rechargeable CMOS batteries
that wouldn't run after I manually recharged them.
Removing/waiting/replacing the charged battery fixed it.