[Nut-upsuser] System with MGE UPS shuts down too early

[Georgi D. Sotirov]

Yes it could be problem with some of the cells. I consider going to the 
service, but I do not have another backup UPS and the service requires 
leaving the UPS for at least 3 days (I presume, so they could perform 
such tests). I'll try replacing the batteries and if it doesn't help, 
then I'll go to the service.


Regards,
--
Georgi

On 27.1.2020 at 10:38, nicolae788 wrote:
> Hello.
>
> I sometimes encountered batteries that were ok, but at times one of 
> the cells would develop a random short/open, therefore reducing the 
> real capacity even if voltage reading was ok. In the absence of a 
> battery load tester i would suggest running multiple tests with a load 
> (car headlight bulb or similar) on the battery outside the ups. This 
> is to eliminate the suspicion of a software or UPS unit fault.
>
> Alex.
>
> On Mon, 27 Jan 2020, 02:53 Manuel Wolfshant, <wolfy at nobugconsulting.ro 
> <mailto:wolfy at nobugconsulting.ro>> wrote:
>
>     On 1/25/20 10:53 AM, Georgi D. Sotirov wrote:
>>     OK, so yesterday evening I done a real test cutting of the power
>>     to the UPS. And it went good... the UPS supported my server for
>>     28:50 minutes (i.e. the expected runtime with this load), before
>>     forcing shutdown. The batteries could still hold as charge was 30
>>     % with about 15 minutes run time. And the UPS did hold for
>>     another full 10 minutes before powering off. These are the
>>     relevant lines from /var/log/ups:
>>
>>     20200124 201318 32 0.0 12 [OB] NA 0.0
>>     20200124 201323 30 0.0 13 [ALARM OB LB] NA 0.0
>>     20200124 201328 30 0.0 13 [FSD ALARM OB LB] NA 0.0
>>     20200124 201333 30 0.0 13 [FSD ALARM OB LB] NA 0.0
>>     20200124 201338 30 0.0 13 [FSD ALARM OB LB] NA 0.0
>>     20200124 201340 30 0.0 13 [FSD ALARM OB LB] NA 0.0
>
>     that looks perfectly fine
>
>
>>
>>     The server was shutdown properly, but for some reason it did not
>>     power off. I saw an error from umount about busy file system, but
>>     I'm sure this doesn't always happen.
>
>     the error is related to your linux system, not to nut
>
>
>>
>>     With everything powered off, I extracted the original batteries
>>     to check them and measure the voltage. The batteries are Leoch
>>     DJW12-9.0 with one of them at 12.57 V and the other at 12.64 V
>>     (measured without load after the discharge).
>
>     That's... surprisingly well, assuming your multimeter indicates
>     correct values. I would have expected values well below 12V
>
>
>
>>
>>     And this morning there was again a short power failure (not more
>>     than 30 minutes, because the router connected to the battery
>>     power from the UPS did hold up). With batteries charged up to 91%
>>     the UPS supported the server for just 07:10 minutes and forced
>>     shutdown with 69% battery charge and over 20 minutes of run time...
>>
>>     20200125 021123 70 0.0 16 [OB] NA 0.0
>>     20200125 021128 69 0.0 16 [FSD ALARM OB LB] NA 0.0
>>     20200125 021133 69 0.0 16 [FSD ALARM OB LB] NA 0.0
>>     20200125 021138 69 0.0 16 [FSD ALARM OB LB] NA 0.0
>>     20200125 021143 69 0.0 16 [FSD ALARM OB LB] NA 0.0
>>     20200125 021148 69 0.0 16 [FSD ALARM OB LB] NA 0.0
>>     20200125 021150 69 0.0 16 [FSD ALARM OB LB] NA 0.0
>>
>>     So, it seems to me that my UPS forces shutdown pretty randomly.
>>     Why the UPS is not waiting for the preset low battery charge
>>     value of 15%? What is actually driving this FSD ALARM and LB
>>     signal when batteries for sure could hold up more?
>
>
>     Can you please show us all the configuration files ? I can only
>     suspect that there is something wrong there because (from a
>     hardware point of view) the UPS behaves very very well, according
>     to your tests and logs.
>
>
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