Running Dynamicc ESS, Cant reach the maximum Charge Current Level

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gdhondt asked Oct 11, '23

Running Dynamicc ESS, Cant reach the maximum Charge Current Level

Hi,

My setup:

3 phase Multiplus II 48/5000
45kWh Battery capacity
Running Dynamic ESS
Location: Netherlands
Max grid current 3X 25A = 17000Watt

I have a question about the maximum charge current of my system. My system is not charging maximum watts/amps what the system is able to do. The multis should be able to charge 3X70A=210A. While the system in the VRM does not reach 180A of charging current.

I have the following options/settings enabled/disabled:

Parameters from my BMS (seplos)

Even if i make my 'grid setpoint' 14000 watts. It still charge my battery with maximum of 9500 watts.

Does anyone have any advice on what I can check? With the Dynamic ess function, I want to use my system as optimally as possible

charge current limit

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Modifications Space

Node Red Space

Answer 1 · 2023-10-12T13:38:43Z

mableeker answered · Oct 12, 2023 at 01:38 PM

What are your settings for DESS (in VRM or Nodered). The to/from grid and to/from battery variables are determining the charge amps, not the grid setpoint for as far I know now.

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Answer 2 · 2023-10-13T06:55:38Z

Dirk-Jan Faber (Victron Energy) answered · Oct 13, 2023 at 06:55 AM

Can you set your systems VRM logging interval to 1 minute instead of 15 minutes.? That way we get some more data to analyze.

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gdhondt commented · Oct 13, 2023 at 12:45 PM

Hi Dirk-jan,

I have set the vrm logging interval to 1 minute. :)

My Dynamic Ess Settings are now set to my maximum charge capacity (9800 watts) otherwise my DESS charge calculations doesn’t match the reality.

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Dirk-Jan Faber (Victron Energy) ♦♦ gdhondt commented · Oct 13, 2023 at 01:37 PM

I did talk to one of my colleagues and he said that the 70A max is at 25°C, and it derates pretty quickly from there. It is pretty typical to see 63A or so per unit (10% down), multiply by 3 and you are around 180A.

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gdhondt Dirk-Jan Faber (Victron Energy) ♦♦ commented · Nov 24, 2023 at 04:04 AM

Hi Dirk-jan.

Still have the issue with reduced charging current

I noticed that if I make my battery monitor “multiplus” visible. Then you see the system thinks it is charging the battery with 10000 watts.

So it looks like there is a bug in the charging monitoring. That’s why the system never reach the maximum charge current of 210A

I think that My reduced charging current is not temp related.

I’m running DESS. But DESS doesn’t affect the max charging current by switching DESS on or off.

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Dirk-Jan Faber (Victron Energy) ♦♦ gdhondt commented · Nov 24, 2023 at 09:52 AM

The smartshunt is more accurate than the multiplus.

160A out of the potential of 210A, is 76%, which suggests an operating temperature of around 60°C. Also see here: https://www.victronenergy.com/upload/documents/Output-rating-operating-temperature-and-efficiency.pdf

Note that the temperature is the temperature within the Multiplus and not the ambient temperature.

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