I have 10 plus UPS Systems that have two Batteries in each.
I believe that "perhaps" one of the two Batteries is failing, and the other is still operational.
I have a very basic Multimeter.
Is there a way I can test each Battery to determine its condition?
Do the UPSs have software to test the UPSs and their batteries? Why do you think there is a problem? If I were to replace the batteries I would replace both at the same time.
Every UPS that I have ever owned has a Test method which shows you if the batteries are up to snuff. Then as MisterEd said, you should replace BOTH batteries at the same time since "if one is bad, the other will surely follow shortly".
I've owned dozens of UPS fwiw and typically find I have to replace batts after3-4 (and occasionally two) years.
To pull the batteries and then the wires from them to test them would be a waste of your time. Of course, if you buy new batts to replace a set in a UPS, then want to test the old batts to see about saving one of them, that is certainly your prerogative to do. A simple voltmeter can tell you what your battery is and an internet search will let you know what good voltages might be for the particular battery you've pulled-out.
The reason I didn't say to pull the batteries and test them is because checking the voltage is not enough. To be meaningful the battery has to have a load on it when checking the voltage. The load could simply be a large resistor. The problem is knowing what the ohms is and its wattage rating is.
For example, you could charge up a battery fully and check its voltage. The voltage might show normal. However, if you try to use it under load the voltage might drop to zero in only a few minutes. Obviously this battery is bad,
Quote