Battery recalibration problem - SMA sunny island system

Hello everybody
I would like to request your help for solving faced problem.
I have SMA back-up solar station with the following configuration:

  1. Sunny Island 8.0H - 3 pcs.
  2. Multicluster box 6.3 -1 pc. (for extention possibility).
  3. VRLA battery 800 Ah x 24 pcs.
  4. Sunny Tripower 15000TL - 2 pcs. - due to solar panel installation maximum solar energy production ~20 kW*h
  5. External grid is connected to system via request as generator
    After half a year of working I have started to get the event 9325 “A 20% recalibration of battery state of charge executed with a leap greater than 10%”. I also read manuals and made requests to manufacturer, but my problem haven’t solved yet.
    Have somebody met the same problem? Could you please reccomend me something?
    Thank you in advance

Hello, from my limited experience with Sunny island systems it sounds like the battery charging parameters are slightly incorrect. Do you have the specification data sheet for the battery?

Is the battery capacity rating (Ah) used the correct rating for the discharge duration. ie. is the C10 rating used and not the C100 rating? (The battery might be 800Ah at C100, but only 680Ah or lower for C10).

Hello, Svarky
Appriciate your responce
I thought about this and checked capacity parameter, here is photo below:
Vladar battery

  1. I had an idea that battery had aged - changed the capacity to 640 Ah, unfortunately without success
  2. Cleaned up all the contacts of 48V DC side
    Also I made voltage measurument of each battery under load:

Interesting so the C rating is correct. What about temperature? Where are you located and do you have the battery temperature sensor connected?

How old are the batteries?

Dear Svarky
Indeed, a temperature sensor isn’t install well:

System in work a little bit more than year. However, I didn’t have this problem during previous summer months.
When I had decided to change an installation place of sensor I faced alarm event of overtemperature (because temperature was slight below threshhold).
I’m going to install air conditioner there and replace sensor.
But, I’m afraid that it doesn’t solve the problem.

I will give feedback as soon as I finish experiment.
Do you have any additional ideas?