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dcsonka avatar image
dcsonka asked

Multiplus2 ESS not charging the battery from AC-IN

Hi,

I have a 3 phase ESS system with 3x Multiplus2 3K 48V and 4x Pylontech US3000C no PV installed yet. It is connected to the grid and in the future, when the PV is connected, I would like to feed back energy to the grid when PV exces power is available.

I am new in the setings and I would like to have a better understanding of the operation details.

Whith the current settings (see attached and below) my observation was as follows:

CerboGX settings:

DVCC-> On

ESS->Mode: Optimized with BatteryLife

ESS->Inverter AC output in use: on (load is connected on AC OUT 1 only)

ESS->Grid Setpont: 50W

ESS->Minimum SOC: 20%

#1 I charged the battery with a single Multi in Charge mode until the charge level reached 85%.

#2 Then I configured the 3-phase operation with the 3 Multis and they charged the battery further to 100% (the front switch was in "On" position on all Multis)

#3 When the batteries reached 100% the Multis started taking power from the battery, only excess power need for the loads was taken from the grid. There was no battery charging anymore obviously

#4 Then after about 16 hours of operation the battery charge level reached 20% (Minimum SOC) and the Multis stopped taking power from the battery and passed the grid through to the loads.

My expectation was that after reaching SOC level 20% the batteries will start charging from the grid again with the Grid Setpoint 50W (i.e. ~1A). However, they didn't start the charging.

Then I swithed the Multis to "Charger Only" mode and after they have synced up to the grid (after ~3min) they started charging the battery with the Grid Setpoint 50W value.

My question is why the charge didnt start in "On" mode, why did I need to switch it to "Charger only"?

The other question is when I install the PV, will I experience the same behavior, or the PV excess power will be charged to the battery even if SOC is set to 20%?

Any feedback is appreciated.

Thank you

battery chargingESS
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1 Answer
Alexandra avatar image
Alexandra answered ·

@dcsonka

Minimum SOC in case of grid faliure.... You set it to 20% that is where it will charge to from grid. The rest of the charge would usually happen with solar (but since there is none the recharge is not happening) this is done to increase self production and consumption.

If you draw under the 20% for example in a grid blackout, when grid comes back it will charge to the 20% and stop there.

For now the way around it is to schedule a charge to get them to 100%, everyday if you are drawing them down during peak times and want to charge in cheaper tarriff windows.

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dcsonka avatar image dcsonka commented ·

Thanks Alexandra, what you say and after reading the user guide, things got clearer. Thanks for the explanation and the pointer to the corresponding chapter (4.3)

I can actually test this by switching off the grid and see whether the recharge really kicks in at 15% (Recharge: ESS will recharge the battery to the minimum SOC limit if it drops more than 5% below the minimum configured SOC. Once the minimum SOC is reached the system once again switches to Discharge disabled.).


Thank you again


Dezso

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