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BackUps CS-500 zero runtime?

APC UPS for Home and Office Forum

Schneider Electric support forum for our APC offers including Home Office UPS, Surge Protectors, UTS, software and services and associated products designed to share knowledge, installation, and configuration.


BackUps CS-500 zero runtime?



I have a BackUPS CS-500.  Status (On Line) light is Green; there are no warning lights.

The UPS is connected via USB to my NAS.  The UPS supplies power to the NAS and to a Mac Mini.


Via the software on the NAS, I can see that the UPS battery is fully charged; and that the load on the UPS is around 40%.  However, estimated runtime is reported as zero.  (I have checked these numbers via the network as well using some separate third-party software.  Note that I do not have access to a Windows machine, so I cannot run 'powerchute'.)


Based on the power curve, I would expect the UPS to be able to power the NAS and the Mac for ~10 minutes.  However, when a power outage occurs, as it did this morning, the UPS switches off entirely within about 30 seconds... just about long enough for the NAS to report a switch to battery mode.


The UPS was purchased new in July 2019; the battery has never been replace (so there are no third-party battery issues at play).  As noted earlier, the status lights on the UPS are all clear.


It's evident that the behaviour during a power outage, and the reported 'zero' runtime, are not correct.  Does anyone have any thoughts about how to troubleshoot?



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Administrator Administrator

Re: BackUps CS-500 zero runtime?



If the UPS shows zero runtime, that indicates the battery/batteries are degraded and cannot sustain the load, even when reporting charged fully. The same as an automotive battery. It can be fully charged, but once you attempt to start the vehicle, a load is applied the charge drops rapidly.

I suggest pulling the battery once charged and checking the voltage. A good battery should read 13.6v DC.

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