I have a UPS that had a fault (not sure what it was, just that it had one). I used the recommended fault clearing procedure. And when I plugged the UPS back in the fault cleared but now I have a battery replacement LED light. I tested the voltage on the battery and it read 26VDC. So I am assuming the battery is still ok. Any ideas on what might be going on? Is there a way to find out what fault I have? The unit has the AP9610 dry contact board.
A test of battery voltage won't tell you much if the batteries aren't actually under load. The sealed lead acid batteries can still appear to have relatively normal terminal voltage even though their ability to deliver sufficient current has disappeared.
There are two ways to verify if the batteries are truly bad. Be aware that this may push weak batteries over the edge, so you may want to have good replacements available if your UPS is protecting an important load.
Both methods produce the same result, and force the UPS to evaluate the actual health of its batteries.
For either method, you may want to remove the UPS from its normal operating environment and attach a "dummy" load running to at least 30% of the UPS's rated capacity. Incandescent light bulbs work well for this. This does two things: it provides a stable load which will produce a "better" calibration result and it means that the UPS won't unexpectedly power off the equipment to which it is normally attached. The UPS should be plugged into a properly grounded outlet no matter which method you choose.
Both methods require that the UPS battery be 100% charged.
The first method is the simplest and can be done with any Smart UPS model. You'll need an outlet strip with a switch, or some kind of switched outlet. Prepare the UPS accordingly by plugging it into the outlet strip, and the outlet strip into the wall outlet. If you wish to use a "dummy" load, connect that (and disconnect anything else). Make sure the UPS is turned on. Give the load a few minutes to stabilize. Turn the outlet strip off, and the UPS should switch to battery. Allow the UPS to run until it shuts off from depleted batteries. Restore power to the UPS after this happens, and allow the batteries to charge for a minimum of eight hours, preferably without interruption.
The second method can be done under software control, if you are using management software with the UPS. It may also be done from the UPS's control panel if it is a later "Microlink" model with an LCD screen that can display status messages, rather than the simple LED indicators used on older models. Command the management software to perform a runtime calibration. This has the advantage that it can be done "in place" without disturbing the UPS or its attached load. (It has the disadvantage that if the batteries are truly bad, the UPS will drop the attached load in what may be a very unceremonious manner.)
You may also direct the UPS to perform a self test, if you are concerned that a full runtime calibration process may ruin the batteries. This will not be as conclusive of a proof that the batteries are good, as the self test lasts only for a few seconds. Even heavily worn batteries can sometimes pass the brief self test.
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