Back-UPS BX750MI - Continuous Beep Alarm After Power Restored

[Buadhai]

I replaced the battery in this unit (Back-UPS BX750MI) a couple of years ago, so I wouldn't be surprised if it needed a new one. This is in my home. The UPS powers a router, an iMac and a Raspberry Pi. I live in Thailand.

Yesterday there was a brief power outage due to a tripped breaker. When I reset the breaker the UPS started a continuous beep. All the front panel lights are blinking at the same time. I checked the battery charge and it was 97%. Within an hour the battery was fully charged, but the beep alarm continued. I couldn't stand the constant and continuous alarm sound so I did this:

sudo upscmd apcups beeper.disable

That stopped the sound, but the front panel lights continue to flash. The current status shows:

battery.charge: 100

input.voltage: 239.0

ups.alarm: Replace battery!

ups.test.result: Done and error

So, is it just a coincidence that the replace battery alarm went off just when power was restored, or is something else going on here?

If the battery does need replacing, I'm torn between doing that and buying a different UPS. Recommendations happily considered.

Note: I have a different APC ups that has IEC outlets. I will never again buy a home use UPS with anything but regular old US style outlets.

[Buadhai]

I'm a bit surprised there is no solution to this. Now I'm sure it's not the battery because the unit operates normally if power is cut and the battery readily recharges to 100% when power is restored.

Here's the full status report:

battery.charge: 100
battery.charge.low: 10
battery.mfr.date: 2001/01/01
battery.runtime: 1741
battery.runtime.low: 120
battery.type: PbAc
battery.voltage: 13.6
battery.voltage.nominal: 12.0
device.mfr: American Power Conversion
device.model: Back-UPS BX750MI
device.serial: 9B2149A11600
device.type: ups
driver.name: usbhid-ups
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: auto
driver.parameter.synchronous: no
driver.version: 2.7.4
driver.version.data: APC HID 0.96
driver.version.internal: 0.41
input.sensitivity: low
input.transfer.high: 300
input.transfer.low: 140
input.voltage: 239.0
input.voltage.nominal: 230
ups.alarm: Replace battery!
ups.beeper.status: disabled
ups.delay.shutdown: 20
ups.firmware: 295201G -302201G
ups.load: 19
ups.mfr: American Power Conversion
ups.mfr.date: 2021/12/03
ups.model: Back-UPS BX750MI
ups.productid: 0002
ups.realpower.nominal: 410
ups.serial: 9B2149A11600
ups.status: ALARM OL RB
ups.test.result: Done and error
ups.timer.reboot: 0
ups.timer.shutdown: -1
ups.vendorid: 051d

[Buadhai]

Looking back on my records I recall that this UPS failed soon after I bought it:

Case Reference: 94936454
RMA Number: 01439749

I guess that after this experience (two hard failures in three years), I won't be buying a battery for this or another APC UPS. They just don't seem to be very reliable.

[Teken]

Based on the information you have provided the continuous beep you hear is due to an overload. I’m not sure why your system indicates a hardware manufacturer of 2021/12/03. 

But your battery indicates 2001/01/01?!? That would make the original battery 24 years old! 🤦‍♂️

If you changed the battery once it’s obvious you didn’t update the installation date. 

The service life of the battery is 2-5 years based on usage, temperature, and environmental conditions. 

If your specific unit came with a data port you can confirm the active fault / error codes via Power Chute Software. You may refer to the user manual here which calls out the conditions for a continuous beep:

https://download.schneider-electric.com/files?p_enDocType=User+guide&p_File_Name=BU-UM-990-6291B-EN....

As of this writing the system appears to operating as intended. Informing you of an overload and to take action to reduce the same. If the root cause is not due to an overload than it’s a internal charging fault.

Complete a Static & Dynamic (Lights Out / Grid Down) test and report back how long the system runs with nothing attached (Static Test) vs a (Dynamic Test) while on your specific load.

Compare it to the APC Runtime Calculator to get a general idea.

Questions Ask . . . 👍

[Buadhai]

This morning (Monday here), I wake up to find that the front panel lights are no longer flashing. The load on the UPS is the same as it has always been: A Raspberry Pi 4, a Deco router and a 2017 iMac. This combination has never caused an overload alert. 

So, I re-enabled the beeper and was greeted with lovely silence. Checking the status of the UPS I find the following:

battery.charge: 100
battery.charge.low: 10
battery.mfr.date: 2001/01/01
battery.runtime: 1682
battery.runtime.low: 120
battery.type: PbAc
battery.voltage: 13.6
battery.voltage.nominal: 12.0
device.mfr: American Power Conversion
device.model: Back-UPS BX750MI
device.serial: 9B2149A11600
device.type: ups
driver.name: usbhid-ups
driver.parameter.pollfreq: 30
driver.parameter.pollinterval: 2
driver.parameter.port: auto
driver.parameter.synchronous: no
driver.version: 2.7.4
driver.version.data: APC HID 0.96
driver.version.internal: 0.41
input.sensitivity: low
input.transfer.high: 300
input.transfer.low: 140
input.voltage: 237.0
input.voltage.nominal: 230
ups.beeper.status: enabled
ups.delay.shutdown: 20
ups.firmware: 295201G -302201G
ups.load: 22
ups.mfr: American Power Conversion
ups.mfr.date: 2021/12/03
ups.model: Back-UPS BX750MI
ups.productid: 0002
ups.realpower.nominal: 410
ups.serial: 9B2149A11600
ups.status: OL
ups.test.result: No test initiated
ups.timer.reboot: 0
ups.timer.shutdown: -1
ups.vendorid: 051d

Looking over old receipts, I realize that I have never replaced the battery on this UPS. I have no idea why the battery manufacture date is so out of whack. I do know that the original UPS failed soon after purchase and was replaced by Schneider in October of 2022. Perhaps they forgot to update the battery manufacture date on the unit (refurbished?) that they sent.

In any event I am no longer being alerted to the need for a new battery or that there is an overload.

I have no idea what's going on, 

[Teken]

You haven’t completed the two tests as requested. The system obviously doesn’t know the true state of the battery capacity as it’s stating 1682 minutes of runtime which is impossible.

Manually initiate a battery calibration with at least 30% attached load and let the process complete. Once the battery is fully recharged show me the stats as above.

Questions Ask . . . 👍

[Buadhai]

Can you please give me a reference on how to: "Complete a Static & Dynamic (Lights Out / Grid Down)" and "Manually initiate a battery calibration with at least 30% attached load". I tried to search on those terms and was not enlightened.

I am using NUT (Network UPS Tools) to query the UPS status and to send me daily notices of the status and also send me notices when there is an error. Ever since I got this UPS I get spurious error notices like this:

When in fact the battery is not low:

battery.charge: 100

Thanks for your help.

[Buadhai]

Sorry for being a dolt, but I see that I can use this:

sudo upscmd apcups test.battery.start.deep

To remove the UPS from AC line power and runs the UPS until the low battery point and then returns to the AC line.

Is that what you were looking for me to do?

I've been running that deep test for half an hour now and the battery is only down to 99% even though it is on the normal load (Raspberry Pi, router, iMac). At that rate it will take many hours to get down to 10%. Of course, the reported battery charge may be way off.

[Teken]

My previous reply calls out how to complete both Static & Dynamic Testing.

Static: Remove all connected loads from the UPS. Remove AC Mains from the wall outlet and track how long the system operates for until system shut down.

Dynamic: You will have at least 30% load connected to the outputs of the UPS. Your system is rated to provide 410 watts of capacity and 30% of that is 123 watts. As such connect this amount of load on the system and than remove AC Mains. Track how long the system operates for until system shut down.

Battery Calibration: This can be manually invoked using APC Power Chute Software. There must be at least 30% connected load on the outputs of the UPS. Let the system complete this procedure and than recharge the battery cartridge. You will see the battery operational runtime will be relatively more accurate vs what you have now.

As a reminder a *Battery Calibration* and Dynamic Load Test is extremely tough on the battery! The battery cartridge is designed to sustain 260 full depletion cycles. Doing the above will be considered a depletion cycle and thus it translates to the 2-5 years of battery life people see.

As the service life is based on *Usage, Temperature, and Environmental Conditions.

Questions Ask . . . 👍

[Buadhai]

Thanks for all the time you spent on this.

I'm gonna give up. This has turned out to be a lot more difficult and time consuming than I'm willing to expend. I tried downloading Power Chute Software but it seems to be only available for Windows machines. (The installer is an EXE file.) The software I'm using on the Raspberry Pi doesn't seem to have a command for calibrating the battery. I ran the deep test for 75 minutes with the normal load on the UPS. After 75 minutes the battery was reported to be at 99% charge. This is impossible because if the power does go out, the battery generally lasts 30 to 45 minutes. No way it's ever lasted more than an hour.

Thanks again.