How to know if the battery is dead?

tbarbette · ‎2024-04-01

Hi all,

My UPS is cutting power in a few seconds when the main power is off. But at the same time the battery health seems to be okay. Here's the result of upsaccess in Linux :

APC : 001,036,0873
DATE : 2024-04-01 20:06:49 +0200
HOSTNAME : tomsrv
VERSION : 3.14.14 (31 May 2016) debian
UPSNAME : tomsrv
CABLE : USB Cable
DRIVER : USB UPS Driver
UPSMODE : Stand Alone
STARTTIME: 2024-04-01 13:43:42 +0200
MODEL : Back-UPS XS 700U
STATUS : ONLINE LOWBATT
LINEV : 228.0 Volts
LOADPCT : 32.0 Percent
BCHARGE : 100.0 Percent
TIMELEFT : 0.0 Minutes
MBATTCHG : 5 Percent
MINTIMEL : 3 Minutes
MAXTIME : 0 Seconds
SENSE : Medium
LOTRANS : 140.0 Volts
HITRANS : 300.0 Volts
ALARMDEL : 30 Seconds
BATTV : 13.6 Volts
LASTXFER : No transfers since turnon
NUMXFERS : 0
TONBATT : 0 Seconds
CUMONBATT: 0 Seconds
XOFFBATT : N/A
SELFTEST : NO
STATFLAG : 0x05000048
SERIALNO : 3B1938X67864
BATTDATE : 2019-09-20
NOMINV : 230 Volts
NOMBATTV : 12.0 Volts
NOMPOWER : 390 Watts
FIRMWARE : 924.Z5 .I USB FW:Z5
END APC : 2024-04-01 20:07:42 +0200

At the same time there is a problem with USB, it takes multiple hours before the UPS is accessible in Linux and I see some problems in dmesg. On Windows it's okay though. That makes me think there could be a problem with the UPS itself, and not just the battery. Still a few month ago the battery lasted for half an hour (full capacity).

I did a test with a 8W bulb (the capacity is shown to be 1% of the max current that can be drained). PowerShute on Windows says it will hold 14 minutes, but actually after 5 minutes the rapid beep starts. After which the UPS stops. Then at restart there is a continuous beep for like 30 seconds. And then it's okay again. Does that mean the battery is dead? Or it might be the whole UPS? Because I never saw the button flashing red, and selftests are totally fine.

Thanks for the help !

Teken · ‎2024-04-02

The rated service life of the batteries is 3-5 years and is based on usage, temperature, and environmental variables. If the batteries are 3-5 years old it’s time to consider a replacement.

You can perform a couple of simple tests to determine the state of health of the batteries.

- Self Test: Generally speaking this test will conduct a POST on the entire system. It will also perform a simple load test on the battery. If it fails immediately the battery is toast and needs to be replaced.

- Load Test: You can do this one of two ways either via the Power Chute software where it completes the battery calibration or simply pulling the AC Mains from the wall.

In both cases there should be at least 30% attached load at the output. If it’s more like (real world) attached hardware even better. If you pull the plug and the unit shuts down immediately or a few seconds the battery is toast - replace! ☝️

If the unit operates for X minutes compare it to the APC Runtime Calculator. If the calculator indicates Y load should offer you 30 minutes with Y load and you only see 5 minutes for example - battery is toast - replace.

If however the system operates for 20 minutes vs 30. It’s time to set aside finances to replace the batteries in the near future of your choosing.

Based on your description the battery is toast . . . 😢

See Answer In Context

Teken · ‎2024-04-02