Making APC 500 Back UPS (basic) work with FreeBSD

Ted Mittelstaedt tedm at
Wed Feb 22 03:07:25 PST 2006

Years ago the APC BackUPSs did come with a serial port.  APC sold the
BackUPS and the SmartUPS.  Both had serial ports, both could be used
to shut down the system.  The difference was you could query the Smart
UPS to findout how much life was left in the battery.

Then 2 things happened, first APC realized
that a lot of consumers out there didn't know or care that their
UPS had a serial port that could shut down the computer, and second
sales of BackUPS were cannibalizing sales of SmartUPS.  So
APC renamed the normal BackUPS with the serial port into the BackUPS Pro,
and came out with a consumer el-cheapo line of throwaway UPS's they
named the BackUPS.

It is no wonder your confused because most documentation on the Internet
for UPSes talks
about backups, but what they are meaning is
upses, not post-apc-getting-greedy-backupses-that-are-named-the-same

Fortunately, the used market is awash in UPSes that have burned out
batteries.  Just find the local supplier of lead-acid gell cells and
make friends with him and your in like flyn.  Any large city has at least
1 of them.

Quite a large number of businesses out there find that it is cheaper to
toss an old 600VA ups and buy a new one when the battery dies, rather
pay some tech for an hours worth of time to pull the old battery and
replace it, then test the UPS to make sure it's still working.  Also,
a lot of techs misdiagnose UPS battery failures and don't know how to
test them anyway.  I've found old APC UPSes for sale very cheap and
very few of them have failed.  Testing is very easy.  Just plug the new
batteries in, and before plugging the UPS into the wall, clip a voltmeter
on the battery terminals.  If you get any voltage rise at all, even a
half a volt, when the UPS is plugged in, the charging circuit is OK.
Then plug a computer into the UPS, turn it on, and unplug the UPS from
the wall and if the inverter goes on, then the inverter is working and
the UPS is perfectly OK.  This test does not work with old batteries
because old batteries often fail in unusual ways.  And the new batteries
should not be at 100% of charge, which they won't be if they have
been on the shelf for a month or so.


>-----Original Message-----
>From: owner-freebsd-questions at
>[mailto:owner-freebsd-questions at]On Behalf Of manish jain
>Sent: Tuesday, February 21, 2006 6:09 AM
>To: freebsd-questions at
>Subject: Making APC 500 Back UPS (basic) work with FreeBSD
>  I just purchased an APC 500 Back UPS (the basic model, not
>the pro/smart one). It does not have any serial/usb interface.
>Can I get apcupsd or any other daemon to work with it so that
>the system automatically shuts down before backup supply runs out ?
>  If someone can attach a sample configuration file, I shall be
>  Thanks
>  Manish Jain
> Yahoo! Mail
> Use Photomail to share photos without annoying attachments.
>freebsd-questions at mailing list
>To unsubscribe, send any mail to
>"freebsd-questions-unsubscribe at"
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.1.375 / Virus Database: 267.15.12/265 - Release
>Date: 2/20/2006

More information about the freebsd-questions mailing list