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UPS Question

DigitalDivide

By DigitalDivide
in General Support

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DigitalDivide Collaborator

DigitalDivide

Posted
Posted

I have a Back-UPS ES 550G which I replaced the battery about 6 months ago.  Tonight the power went out in my condo and within 2min I got a message from my tower that it was shutting down.  I got two emails which are below.  What surprised me is how fast the tower shutdown.  The power outage only lasted 5 min. When I look at the UPS Settings on the Tower it shows the specs below.  I'm not sure what item I should specifically be looking at.  I only have the UPS and my router and modem plugged in and nothing else.  I'm really surprised it didn't last longer.

 

1st

Event: unRAID Server Alert
Subject: UPS Alert
Description: Power failure on UPS Tower. Running on batteries.

 

2nd

Subject: UPS Alert
Description: Battery time limit exceeded on UPS Tower. Doing shutdown.

 

 

APC 001,034,0839 DATE 2018-02-20 22:01:08 -0500
HOSTNAME Tower VERSION 3.14.14 (31 May 2016) slackware
UPSNAME Tower CABLE USB Cable
DRIVER USB UPS Driver UPSMODE Stand Alone
STARTTIME 2018-02-20 21:52:02 -0500 MODEL Back-UPS ES 550G
STATUS Online LINEV 121.0 Volts
LOADPCT 36.0 Percent BCHARGE 82.0 Percent
TIMELEFT 13.2 Minutes MBATTCHG 10 Percent
MINTIMEL 10 Minutes MAXTIME 30 Seconds
SENSE Medium LOTRANS 92.0 Volts
HITRANS 139.0 Volts ALARMDEL 30 Seconds
BATTV 13.6 Volts LASTXFER Unacceptable line voltage changes
NUMXFERS 0 TONBATT 0 Seconds
CUMONBATT 0 Seconds XOFFBATT N/A
STATFLAG 0x05000008 SERIALNO 4B1448P27100
BATTDATE 2014-11-27 NOMINV 120 Volts
NOMBATTV 12.0 Volts FIRMWARE 904.W1 .D USB FW:W1
JonathanM Grand Master

JonathanM

Posted
Posted

Sounds about right for a UPS that small. Do you happen to remember what Ah spec the battery was?

 

Also, remember that in order to shut down, unraid has to spin up all the drives and do shutdown housekeeping, so the current draw during shutdown is pretty close to max, much more than idle.

Frank1940 Veteran

Frank1940

Posted
Posted

IF you look at the output from the 'UPS details' chart in the original post, you will see that this:

     

MAXTIME 30 Seconds

 

This is the time that the UPS will supply power on battery before it signals for the shutdown procedure to begin.

 

BTW, this is actually a good value to have this short a time before shutdown start.  The problem with using longer times are many.  The two must important ones are these.  First, the time on battery at present load is a SWAG (Stupid Wild A$$ Guess).  As the battery ages, this time is even less accurate and the battery can fail to supply the required current and the UPS will just shutdown at that point.  Second point is the one which the OP referenced.  The power comes back on after being out for a few minutes.  Someone assumes that it is back on for good and restarts the server.  Ten minutes (or even two hours) later, it goes out again. The battery has not recharged enough to conduct a clean shutdown.  (It will take about eight hours to fully recharge the battery.)

Frank1940 Veteran

Frank1940

Posted
Posted

A UPS for a few hours is called a generator....   A lead acid battery with that type of capacity would be the size of a file cabinet drawer! The objectives of a battery powered UPS are (1) to shut the system down cleanly and (2) to prevent power transients from causing damage to both equipment and data.  

JonathanM Grand Master

JonathanM

Posted
Posted
8 hours ago, DigitalDivide said:

I just thought it hold for a few hours but I guess I would have needed a bigger one.

For a few hours of clean power, plan to spend well over $1,000 USD, and have a cabinet just for the batteries, and another for the UPS electronics.

 

 

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