45. My APC UPS keeps reporting OL LB, even after it’s been charging for many hours. What can I do about this?

This happened to me, and some other people too. The combination of our experiences should prove useful to you.

First, you need to realize that the UPS apparently stores data about the battery, load, and runtime. After replacing the battery, it needs to be clued in to the new situation. If the traditional runtime calibration doesn’t work, you have to try something a little more drastic.

You need to completely drain the UPS while it has a good ground. This means you can’t just pull the plug. You also have to disconnect it from the computer so this software won’t shut it down.

The easiest way to do this is to first unplug your computer(s) from it, and plug in a token load like a lamp. Also, move the UPS to a power strip that doesn’t switch the ground line or an outlet that you can switch off at your panel.

Once the UPS is up at 100% charge (this is important), disconnect the power. It must remain connected to the ground, or the results may not be accurate. Ignore the sounds it makes, and go away until it’s done. Don’t do anything to the front panel while this is happening.

After all of this, put things back the way they should be and let it charge up. You should find that it again gives reasonable values and behavior, as it was when it was new.

Thanks to Matthew Dharm for helping us nail down this procedure.