On 03 Feb 2009 01:34:13 GMT, Warren Post wrote:

I just replaced the battery in my UPS, and notice that the old one was
swollen and hard to remove. Searching this NG and elsewhere on the net, I
see this means that the battery had reached the end of its life some time
ago and should have been replaced sooner. Okay, replacing the battery
when it reaches the end of its life cycle instead of waiting until it
obviously fails is fine by me.

So how do I know when to replace a UPS battery? This particular UPS has
no self test feature and no com port with which to communicate with the
computer, and I don't want to toss perfectly working equipment into the
landfill just because it lacks bells and whistles to make my life a
little easier.

If nothing else, just use a two year schedule. A good UPS will
constantly evaluate the batteries and advise you when they are near
the end of their life. But that is only for the high end ones, not a
garden variety 500 to 1000 watt version.

A life test (such as the one suggested by the other poster, two 100
watt lamps (for a 400-500 watt unit) will work. You can compute how
long it should keep the lights on, and see what you get. Generally
when batteries get to the failure point, they discharge very quickly
(a couple of minutes max) instead of the expected 10 to 20 minutes a
UPS should provide.