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

[Manuel Wolfshant]

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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