On Mon, 5 Jan 2009 13:04:49 -0800 (PST), BrianAlex
wrote:

Hi. I have a UPS that is not functioning correctly. It's an APC
"Professional Powercell" 250 watt
unit that is at least 5 years old.
When there is a power outage, it beeps loudly but there is no current
to the outlets (computer is plugged to this).
I took out the 12 v lead battery and it tests 13 volts.
I pushed the "re-set" button.
I dismantled the case ("no user serviceable parts) and there is a
note to use only the same size fuse. Well there is no indication where
the fuse is,and I believe this may be the problem since at one time I
had too much stuff plugged in (not being aware of it's 250 W limit).
There is an orangish part that looks like a plastic plug-in
automobile fuse that says"40" on top and on the solder side says "40A
32V". I checked from this side and it has continuity,plus the element
in it appears solid.
Would there be a fuse somewhere else? I don't see one.
Also I see a "APCC (C) 1993" on the board so maybe this thing is that
old.
What else would cause this failure?
I consider this a learning opportunity,and I am a cheap so-and-so and
will not be paying the big bucks for a new one any time soon!
Your advice greatly appreciated.-Brian

Most common failure mode of this class of UPS is u/s battery. They dry out due
to overcharging. (The charge regimes employed are brutal on batteries, in the
interest of fast recovery). They present as fully charged in terms of terminal
voltage because they have a very small residual capacity, but can't cut the
mustard when it comes to driving the inverter even at idle.

Try connecting an automobile battery instead and see if the UPS functions. That
way you can quickly determine whether it is the battery or the electronics
causing the problem.