Bx950Mi issue with "apcupsd" and "Network UPS Tools (NUT)"

[abcek]

Hi,

my APC Back-UPS 950 (IEC) just died (had red "replace battery" led, replaced battery, made 5sec power button reset with battery disconnect and the battery doesn't charge) so i decided to buy a new UPS.

as Back-UPS 950 is now discontinued I was inclined to buy a Bx950Mi (IEC).

The problem is that I found on different posts in different forums that this new BX___Mi line model allegedly seems to have a flaw in the firmware that makes it unusable with linux using "apcupsd" or "Network UPS Tools (NUT)" because the firmware trough USB report data that push "apcupsd" or "NUT" to trigger a system shutdown event even if the battery is at 95%.

Other user allegedly seems to say that the UPS when start a self test report it in the wrong way trough the usb interface and "apcupsd" or "Network UPS Tools (NUT)" see this as a battery error/battery disconnect.

For NUT it seems that developers found some workaround to ignore for a time space of 3 seconds the allegedly wrong data reported by the UPS starting with NUT version 2.8.1 (that ships only with Debian 13 Trixie, If you are on older distro you need to compile yourself).

TrueNAS 25.10.1 is Debian 12 based, so there is no mitigation for NUT on this platform.

here is what I'm talking about: https://github.com/networkupstools/nut/issues/2347

also allegedly there is this USB data stale issue: https://github.com/networkupstools/nut/issues/2805

So I have some question:
1. do you acknowledge your Bx___Mi line has any firmware issue?
2. do you shipped or plan to ship a fixed firmware?

3. it's possible to update the product with the old firmare in the hand of your clients with the new firmware?

4. if NO and I'm buying now the product how can I know it has the new fixed firmware?

4. also if NO, do you plan to issue a recall or a RMA with shipment at your expense to whoever want a unit with the new firmware?

For the value you ask I'd like to buy a product that flawlessy works with "apcupsd" or "Network UPS Tools (NUT)".

I'd like to have an answer and I will not buy a new APC product until these questions find an answer.

Please consider users that are using Bx___Mi on linux are allegedly experiencing these issue and are reporting it so if there is an issue with the firmware please don't ignore it, acknowledge it, find a solution and use your PR department to let people know (for example on github NUT issue tracker) you solved this allegedly firmware issue and how to obtain a product with the last firmware.

Thanks.

[Teken]

Why wouldn’t you simply replace the RBC in the older unit?!?! I’ll assume this specific model APC UPS worked fine on NUT??

As to your point about this newer model only hands on testing and validation in your environment will yield the facts.

Going off on what’s published on the internet does not offer all the facts or variables at play.

Also, the only officially supported software  for any APC UPS is Power Chute Software such as (PCPE, PCSS, PCBE, PCNS).

Any other 3rd party software is based on open source information and the community at large.

None of them have standing as it relates to working / not working with a specific APC UPS. As the software is based on what is publicly known and trial / error to break fix issues.

Lastly, it’s highly unlikely you will receive a formal reply to any of your questions in the APC Forum.

As an aside, no Back-UPS Series system has field upgradable firmware - None.

This ability is present in all current generation of APC Enterprise UPS that encompasses the Smart-UPS Series such as SCL, SMC, SMT, SMX, SRT, SRTL, SRYL, XP, XU.

As it relates to a recall based on third party software??? There’s a higher likelihood you’ll be struck by lightning three times in your life before that happens!

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[abcek]

Thanks for the answer.

what do you mean with RBC?

If you meant "Replacement Battery Cartridge" as I already told I already performed a Battery replacement with a new one to fix the issue, but the UPS attached to the main power draw the new battery and turned on the red led "replace battery". This happen because the UPS never start to charge/maintain the battery power.
I read that this issue could be cause by some capacitor on the main board dry out and need to be replaced, as I'm not able to make any soldering, the solution for me was to buy a new one.  On Amazon I found only the new models (and at this point I don't want to buy an older model that now cost more than the new one and has inside a battery that sat on the shelf for a long time)

I was using the older unit with apcupsd on Debian.

[Teken]

You haven’t answered the question regarding whether the new UPS operates fine with NUT?!?!

As it relates to the old unit not properly charging the RBC. Typically, it’s one or more board level components that are out of tolerance.

A quick google search will give you a starting point if you have no board level experience in troubleshooting. Ultimately the model you have is so cheap relative to enterprise hardware it’s easier to just replace the entire unit with new like you did.

The only benefit of repairing the old unit is personal knowledge, experience, and restoring something that was broken and using it again.

There are several YouTube videos on similar problems and what they found as the problem.

It can be as simple as a bad / out of tolerance capacitor, resistor, diode. Capacitors that are out of specification or simply leaking / bursted are easy to identify. Capacitors that are high ESR require a dedicated meter to identify as a basic meter can easily show proper capacitance and still have high ESR.

This is why some components must be taken out of circuit and measured with the proper tools and not just a multimeter when the problem is more involved.

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