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dionw asked

Have I got a setting wrong?

Equipment: MultiPlus-II 48/3000/35-32 (ACOut2 switchable) , Venus GX , BMV-700 , BlueSolar Charger MPPT 150/100 , Energy Meter ET112 , 4 X Deltec (48V) 3 Years old,

When the grid fails and the SOC is on 89% the inverter switches off. I am using average 600W from the system when the grid is off and seldomly get more than 100 minutes from the system before it disconnects. I have tried all the different ESS settings, but it does not seem to have an affect. Still stops at about 90% SOC.

I have disconnected the batteries and tested them individually. Does not seems as if one is faulty. Am I missing something? Is this normal?

ESS
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
Can you give us more information about the batteries? (Exact name or datasheet)

Please make some screenshots of the settings (VE.config and GX device).
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dionw answered ·

br-12v200-spec-sheet-26022019.pdf (4.8 MiB)
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dionw answered ·

ve-settings.pdf (238.6 KiB)
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dionw answered ·

gx-settings.pdf (66.8 KiB)
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dionw answered ·

vrm-reports.pdf (92.4 KiB)
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Matthias Lange - DE answered ·

Please make a screenshot of the settings of the ESS Assistant (click on the assistant and than on summery)

I think you hit the dynamic low voltage cut-off values.
200Ah lead batteries is not much for a 5kVA MultiPlus.

Did you limit the max charge current into the batteries with DVCC?
(max. 10-15% of the capacity -> 20-30A for your system)

Normal AGM batteries are not good to use in ESS, I thing they are almost dead.

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dionw answered ·

Thank you for responding. It is a 3kva system.ESS Summary.pdf


ess-summary.pdf (64.0 KiB)
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nickdb avatar image nickdb ♦♦ commented ·
Please include the VRM chart of the battery voltage and current over time.
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dionw answered ·

battery-voltage-and-current.pdf (52.5 KiB)
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dionw answered ·

more-charts.pdf (76.2 KiB)
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nickdb answered ·

Your batteries look dead. The voltage drops to 48V which is pretty much flat and thats at the ESS dynamic cutoff, yet SOC is reported as above 80%.

3 years is a good run with those type/size batteries and ESS.

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dionw answered ·

That is not good news, although I had a suspicion that I will need to replace them soon. What size Lithium would be sufficient?

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nickdb avatar image nickdb ♦♦ commented ·

Well that's hard to say. How much storage do you need, how deep are your pockets?

Lithium has a wider usable range and you should plan to try keep 20% in the tank.

If the current capacity has worked for you then something 5kWh and above should be ok, but with batteries more is more (and there are minimum requirements for discharge current so make sure the packs meet them).

For supported batteries and minimum requirements have a look here:

https://www.victronenergy.com/live/battery_compatibility:start


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