UPS with Mac Mini Pro M2 not functioning correctly

Question

UPS with Mac Mini Pro M2 not functioning correctly

There is a previous thread about this which is now closed, but I have the same symptoms which are that I have a APC 350W UPS connected to my M2 Pro Mac mini by USB cable, and although System Settings shows that it is connected, and says that it is a "Back-UPS CS 350 FW:807.q5.I USB FW:q5", whatever I set the settings to the Mac mini shuts down the instant the mains power drops.

One additional things is that the menu bar icon says that the UPS is at 1,000% charge level.

If I click on the icon it also says that "UPS is not charging". It is not clear whether this is because it is already fully charged (ten times over!) or maybe it is saying that the UPS is not able to charge the battery - I don't know which it is trying to say.

This UPS used to work absolutely fine when connected to my 2019 27" iMac until a week or so ago when I finally transferred full-time to the Mac mini, so I don't think the UPS is faulty, but the lack of UPS functionality with the Mac mini (running Ventura 13.5) is a big frustration.

Mac mini (M2 Pro, 2023)

Posted on Aug 28, 2023 3:30 AM

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Answer 1

lkrupp

Level 7

26,285 points

Aug 28, 2023 5:11 AM in response to ncollingridge

Try this test. Unplug the APC USB connector from your Mini, then pull the plug on the APC and see if your Mini shuts down or keeps working. If it shuts down it means you need to replace the battery. Three years is about the max for these types of batteries.

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Answer 2

Aug 28, 2023 3:55 PM in response to ncollingridge

I am not exactly sure what is going on with the first UPS, but trying a different one has resolved the problem.

I tested the voltage of the battery in the first UPS and it was very healthy - right up at nearly 13v. And now with the new UPS (same model, same vintage) the menu bar icon says that the battery is now at 100% rather than 1,000%. So maybe that is a symptom of a failing UPS circuit board?

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Answer 3

Aug 28, 2023 8:03 AM in response to lkrupp

The UPS does not have its Replace Battery light on, and it worked literally one week ago with my iMac. Also the battery in it is a replacement since the UPS was new and is probably only about two years old. I will, however, try as you suggest to remove the UPS cable and see what happens.

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Answer 4

Aug 28, 2023 3:56 PM in response to ncollingridge

Just to add that the firmware of the newer UPS is Back-UPS CS 350 FW:807.q10 .I USB FW:q10 - very similar except for the q10 instead of q5.

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UPS with Mac Mini Pro M2 not functioning correctly

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