Slow battery charging

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mmh asked Jun 27, '22

Slow battery charging

I work in a hospital in Mulanje (Malawi). We have recently connected 6 Quattro (6x15kW) with 6 Fronius Symo (6x15kW) AC-coupled. We have 6 battery banks (29 batteries in total). Each bank has a BMV and battery capacity of 500Ah (5x100Ah). 1 bank is different with 400Ah (4x100Ah). It is in Malawi not allowed to feed back to the grid. The system is running pretty good but we are dealing with the next issue.

When there is not enough solarpower to provide the load of the hospital and to charge the batteries the system is not using the grid to charge the batteries. For example we have a powercut and the batteries will be discharged until 8% and the powercut is over it will not start charging the batteries from the grid to the minimum SOC set in the ESS. Also not when i enable the setting 'keep battery charged'. Only when there is enough solarpower it will use the batteries to store the load. what can i do to change this? See pictures for more info. Thanks in advance.

battery charging ESS

ess-settings-battery.jpg (230.2 KiB)

cerbo-dashboard-on-rainy-day.jpg (336.4 KiB)

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seb71 commented · Jun 27, 2022 at 10:19 AM

ESS should stop the discharge when the SOC reaches Minimum SOC and grid is present.

In your last screenshot that is not the case.

So it seems that ESS is not working.

Is the ESS Assistant configured and running in all the Quattro inverters?

Yeah, in 3-phase setup, all inverters should be connected to the same battery.

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marekp seb71 commented · Jun 27, 2022 at 10:25 AM

@Seb71

His problem is with system not charging from the grid when grid is back from being down.

But when grid is down battery will by drained down to zero.

Probably what we see is the moment when grid is back after long down period.

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seb71 marekp commented · Jun 27, 2022 at 10:27 AM

Yes, but in the last screenshot there is grid, SOC is 1.5% (so it must be under Minimum SOC) and the battery is still being discharged.

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marekp seb71 commented · Jun 27, 2022 at 11:13 AM

It is probably discharging just at that moment because there is BULK charging phase indicated.

The question is, how many GX devices he has.

How it can work with one GX and so many batteries with BMV for each and 6x15kW Froniuses?

Do you see 6 Froniuses in that VRM screen shot?

I am probably to dumb to understand it.

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lifeingalicia answered · Jun 27, 2022 at 11:13 AM

Read carefully through the ess install menu

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/configuration.html

e.g.

4.3.9. Limit charge power (should be off)

This setting limits the amount of AC power used by the Multi for battery charging. The limit also applies to AC power received by the Multi from any grid-tie PV Inverters connected to AC-in.

In other words, this setting limits the flow of power from AC to DC on utilities connected to AC-in.

This setting does not reduce the charge power coming from MPPT Solar Chargers.
This setting only applies to utilities connected to AC-in: In inverter mode, the 'charge-current setting' - as configured in VEConfigure - is used to control power coming from grid-tie PV Inverters.

4.3.6. Minimum Discharge SoC (unless grid fails)

If nothing helps a workaround maybe to put the system on scheduled charge a couple of times during 24 h which will stop any discharging during the selected time and charge to elected SOC

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Modifications Space

Node Red Space

Answer 1 · 2022-06-27T10:11:07Z

marekp answered · Jun 27, 2022 at 10:11 AM

@MMH

I have never seen the installation of Victron with separate battery for each Inverter/charger in 3-phase/2 parallel configuration, but I am new to those systems.

Unless I misunderstood your description.

Can you provide the schematic of this installation?

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Answer 2 · 2022-06-27T10:20:58Z

Juha Tuomala answered · Jun 27, 2022 at 10:20 AM

Do you have scheduled charging activated? I noticed that when I do, Quattro II won't start charging even I manually switch inveter from 'On' to 'Charging' mode. Only way to charge it is to create a manual schedule that overlaps the current time.

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Answer 3 · 2022-07-31T10:57:45Z

mmh answered · Jul 31, 2022 at 10:57 AM

Hi all, thanks for help.

This particular issue was resolved by forcing charge using 'keep batteries charged' in ESS once. Now charging from both grid and pv with adequate current up to 500A.

Still some other issues remaining for which a new post opened, 'High frequency issue'.

Thanks again

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Answer 4 · 2022-07-31T11:07:22Z

mmh answered · Jul 31, 2022 at 11:07 AM

@MarekP

In this system the quattros are all on one DC busbar connected to 6 battery banks.

Each bank has a BMV and, for now, the Quattro provides battery information for ESS, so this includes voltage and current for the entire DC busbar.

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marekp commented · Jul 31, 2022 at 11:12 AM

@MMH

Are those BMVs connected to GX?

If yes than, which BMV is providing battery information to GX for ESS to know the SOC if you have 6 of them?

You have 6 Quattros but, are they working on separate circuits and each has its own GX unit?

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