2 Units, both give "connect batteries" error even though pack is at 25VDC? Batteries or units the problem?

[PatM1]

I have 2 units XS 1300 and SMT750C, both take 2 12v batteries in a pack. I have 2 seemingly good batteries, both meter at over 12V, the pack gives 25.5Volts. Both units do not recognize the pack, they give the "connect Battery" message. I don't mind buying a couple of batteries, if that's the issue. Any ideas how to troubleshoot from here?

[Teken]

You’ll need to provide a lot more information as it relates to the following:

Serial number, battery production date, logs: event, data, ups, diagnostics.

The average service life of the RBC is 2-5 years based on usage, temperature, environmental conditions. The cells are rated for 260 full cycles before signs of degradation with the same caveats listed above.

Generally speaking the error message you see indicates the RBC is EOL / Expired. You may perform a rough test by disconnecting the series connected RBC.

Measure the initial float charge and document and report here. Allow the RBC to sit disconnected from one another for a minimum of 72 hours or longer then measure the voltage and report back the same.

Expected voltage drop is 0.1 ~ 0.3 VDC. Any individual cell that drops 1-3 VDC after the surface charge has been removed indicates a bad cell(s).

Do not rely on the APC Self Test for a Go / No Go RBC as being healthy! ☝️ By the time it actually declares a RBC fault / expired it’s too late.

You may certainly try the same to see the results and report back the same. Assuming you did not have the Connect battery fault.

You would simply mimic a Lights Out / Grid Down event and remove AC Mains to see how the system behaves and the operational runtime obtained.

Than compare the same to the APC Online Runtime Calculator.

NOTE: In some edge cases the error displayed literally means the RBC is not connected. As such verify the internal fuse isn’t blown open if present.

All connectors, wiring are corrosion free, tight, and properly mated. Validate any Anderson connector mating surface on both ends are making proper contact.

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