I replace the battery in mine about every 2 years for the same reason.<BR><BR>If you hook it up to a linux machine you can query the UPS and see if the EPROM reports the age.

Doing this upgrade (which is only $10 more if you buy the 9Ah battery directly from APC) will give my system an additional 2Ah of capacity, which should deliver nearly 30% more runtime than before.

The battery on my UPS died (APC BE550R), so right now it only functions as a 4 plug surge protector, since the battery plug are useless. I was looking at replacement batteries, but I might end up ...

The GOLDENMATE UPS uses a Lithium Iron Phosphate (LiFePO4) battery, which lasts much longer than regular lead-acid batteries. It can handle over 5000 charge cycles and lasts more than 10 years.