MultiPlus 48V 8000 Low Battery Alarm

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duncangardiner asked Aug 13, '23

MultiPlus 48V 8000 Low Battery Alarm

Hi everyone. I have a Victron MultiPlus II 48V 8000 inverter as part of my solar system. Its mostly there to invert with a small requirement to charge from the grid on dull days.

Its connected via the VE-Bus to a CebroGX. I have a RS MPPT 450/100 charge Controller managing the solar panels. And I have RosenPV 48V batteries (2 10Kw pakcs).

Initially when I installed the MultiPlus inverter it took the Battery charge state from the RS MPPT charge controller. However I wanted to harvest data from the Victron gear into a home automation system (Home Assistant) that is on the same network as the CebroGX.

So I followed the installation guide to add an assistant to the MultiPlus (the ESS assistant). This is required to open up the MQTT port that Home Assistant can monitor and receive data via.

I did have to create a custom battery profile in the MultiPlus' Charger setup, but I used the same settings as the RS MPPT charge controller has.

Now when I switch on my MultiPlus Inverter, it throws a LowBattery alarm and turns itself off.

Here are a few phots of the main screen for my set up.

I created this RosenPV Battery profile, but copied the setting from my RS MPPT 450/100 charge Controller, which work fine there.

Virtual Switch is off otherwise you can not install any assistants

This ESS assistant is required for MQTT connections to be turned on.

Not sure what this shows, I added it for completeness.

Can anyone tell me where I have gone wrong?

Kind regards

Duncan

Multiplus-II ess settings

cebrogx-multiplus-screen.jpg (74.7 KiB)

low-battery-alarm.jpg (68.7 KiB)

multiplus-config-general.jpg (185.0 KiB)

grid.jpg (200.9 KiB)

multiplus-config-inverter.jpg (198.1 KiB)

multiplus-config-chrager.jpg (200.1 KiB)

multiplus-config-vurtualswitch.jpg (185.0 KiB)

multiplus-config-assistants.jpg (184.0 KiB)

multiplus-config-ve-bus-monitor.jpg (78.9 KiB)

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Answer 1 · 2023-08-13T16:13:15Z

seb71 answered · Aug 13, 2023 at 04:13 PM

For 16-cell LiFePO4 a battery voltage of 49.84V (under no load/no charging) is close to empty.

When using ESS, the low voltage settings are those configured in ESS (which you did not list).

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duncangardiner commented · Aug 13, 2023 at 06:07 PM

Hi @Seb71

Ok here are all the ESS settings I can find. Most are on the CebroGX.

The Configuration tool only lets me add the ESS assistant, it gives no means to add any changes. The Summary page I assume is guidance rather than my actual setup?

Kind regards

Duncan

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ess-modes.jpg (75.3 KiB)

ess-settings-1.jpg (90.0 KiB)

ess-settings-2.jpg (74.9 KiB)

multiplus-config-assistants-ess-summary.jpg (132.0 KiB)

seb71 duncangardiner commented · Aug 13, 2023 at 06:14 PM

At first glance: your Dynamic cut off voltages are set very high (the 0.005 C / 52V and 0.25 C /50V ones) for a LiFePO4 battery.

If your battery is 16-cell LiFePO4, try these:

0.005 C = 49.50V

0.25 C = 49.00V

0.7 C = 48.50V

2 C = 48.00V

For Sustain voltage: 50.40V (you can tweak this later, if needed).

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But check if your battery is LiFePO4 16-cell or LiFePO4 15-cell.

The charging voltages are also too low for a 16-cell.

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The Configuration tool only lets me add the ESS assistant, it gives no means to add any changes. The Summary page I assume is guidance rather than my actual setup?

No, those are your actual ESS Assistant settings.

You can modify with "Start assistant" button or you can delete the ESS Assistant and re-configure it from scratch.

But better take a look at the manuals first.

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

https://www.victronenergy.com/media/pg/VEConfigure_Manual/en/index-en.html

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

https://www.victronenergy.com/live/assistants:how_to_add_and_configure_an_assistant

https://www.victronenergy.com/live/assistants:how_to_update_an_assistant

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duncangardiner seb71 commented · Aug 13, 2023 at 06:54 PM

@Seb71

Thanks Seb. I used the start Assistant button in the VE Configure tool, and worked my way through each screen using your setting. I think my Battery is only a 15 cell not a 16 cell. but the inverter is back on and seems happy again.

Kind regards

Duncan

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seb71 duncangardiner commented · Aug 13, 2023 at 07:03 PM

If the battery is 15-cell, the Dynamic Cut-Off voltages can be set lower.

But don't reduce them until you know for sure how many LiFePO4 cells (in series) your battery has.

The Float voltage (51.9V) is too high for 15-cell LiFePO4. If your battery is 15-cell, set Float to 50.25V.

The Absorption time (8 hours) is probably too long.

In Cerbo:
"Optimized without BatteryLife" mode is the better choice for LiFePO4 in my opinion.

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