Tonight another UPS failed. Same brand as before, these little black APC units. It failed the same way as the last one, by going into a perpetual 15 second power off/on cycle. I had bought these small units to run my little router and cable modem, wanting to have a separate power source for the cable modem than I had for my big power hungry computers. The idea is that during an extended power outage my cable modem could actually stay up for a couple of hours (and so could my laptop batteries). This strategy paid off for me a couple of years ago when I was working for MySQL, I actually lost power for several hours but was able to keep working with the rest of the team, just sat there in the dark and ran off the laptop battery.
It is quite strange that these little black APC units seem so prone to failure, I've also got a couple much larger APC battery backups and those are still running just fine.
At any rate, I'm happy that the battery backup finally had a catastrophic failure. I believe it was intermittently failing because I was getting intermittent network outages every day or two for the last couple of weeks, and it was annoying. I noticed the outages because I actually have a couple of services that I am trying to keep running, like the bot that announces on our private IRC channel at work whenever code is merged into the main Launchpad source tree, and some other similar things.