battery voltage and self test

[Trantor]

running on linux server : apcaccess status

the result is

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APC : 001,036,0879
DATE : 2023-10-13 18:57:28 +0200
HOSTNAME : wineportserver
VERSION : 3.14.12 (29 March 2014) debian
UPSNAME : upswine
CABLE : USB Cable
DRIVER : USB UPS Driver
UPSMODE : Stand Alone
STARTTIME: 2023-10-13 18:57:26 +0200
MODEL : Back-UPS BX1600MI
STATUS : ONLINE
LINEV : 226.0 Volts
LOADPCT : 12.0 Percent
BCHARGE : 100.0 Percent
TIMELEFT : 40.0 Minutes
MBATTCHG : 25 Percent
MINTIMEL : 5 Minutes
MAXTIME : 600 Seconds
SENSE : High
LOTRANS : 145.0 Volts
HITRANS : 295.0 Volts
ALARMDEL : 30 Seconds
BATTV : 27.2 Volts
LASTXFER : Automatic or explicit self test
NUMXFERS : 0
TONBATT : 0 Seconds
CUMONBATT: 0 Seconds
XOFFBATT : N/A
SELFTEST : NG
STATFLAG : 0x05000008
SERIALNO : 9B2143A15351
BATTDATE : 2023-01-20
NOMINV : 230 Volts
NOMBATTV : 24.0 Volts
NOMPOWER : 900 Watts
FIRMWARE : 294201G -302201G
END APC : 2023-10-13 18:57:30 +0200

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first question :

why is the battery voltage at 27.2?
Aren't they 12V batteries?

second question :

during self test (I disabled apcupsd) I receive this messagge

----------------------------------------------------------------------------

This test instructs the UPS to perform a self-test
operation and reports the result when the test completes.

Clearing previous self test result...FAILED

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I think the self test was not completed why?

Thanks for your help