Luke Siemaszko wrote:
In the meantime I'd still l ike to try and fix the one we have. Has
anyone got any experience of this, or any schematics even?

Some of these have automotive-type blade fuses in the battery line on
the circuit board. Also, as has been mentioned, try a new battery.
I have had good luck with Power Sonic and Panasonic brand gel cells.

Note that most of these will go into a test mode for a few seconds on
startup, and when this happens, quite a large current is drawn from
the battery for a moment. If you are lashing up some random battery
you have lying around, use wires at least as large as the ones already
in the UPS. I tried to start up a APC Smart-UPS 600 with not quite
the right batteries and a cheap ~20 gauge clip lead and melted the
clip lead.

If you get it running, but it complains about a low battery even when
you know the battery is fully charged, go to
http://us1.networkupstools.org/faq/ and read the answer to "Q: I
replaced the battery in my APC Smart-UPS and now it thinks the battery
is low all the time. How do you fix this?"

Matt Roberds