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urban-caterpillar avatar image
urban-caterpillar asked

Multiplus 3000 II-GX cuts out when battery voltage is fine

Hi all. My off grid system comprises of:


Multiplus 3000 II-GX

Smart Shunt

Victron MPPT with 3.4kw solar PV

12kwh Powerplus lithium batteries.


Recently the Multiplus has been shutting down on 'Low SOC', as displayed on the screen. It seems to cut out way before the battery voltage gets close to the low voltage cutoff which I have programmed at 50.0v. Today it cut out at 51.75v, which is close to 60% SOC.


Does anyone have any ideas as to why it cuts out so early? Please see the programmed settings I pulled from the Multiplus just below.


TAB: General

System frequency 50Hz

Shore current 8.0 A

Overruled by remote checked

Dynamic current limiter unchecked

External current sensor connected (see manual) unchecked

State of charge when Bulk finished 95.0 %

Battery capacity 250 Ah

Charge efficiency 0.95

TAB: Grid

Country / grid code standard Australia A: AS/NZS 4777.2:2020 stand alone app. M (no N-bypass)

AC input 1 Above selected gridcode plus LOM B (compliant)

TAB: AS/NZS4777.2:2020 Australia A (Stand alone appendix M)

Volt-Watt curve voltage V1 207.0 V

Max charge power at V1 20 %

Volt-Watt curve voltage V2 215.0 V

Max charge power at V2 100 %

TAB: Inverter

PowerAssist unchecked

Inverter output voltage 230 V

State Of Charge shut-down 20.0 %

State Of Charge restart 25.0 %

Inverter DC shut-down voltage 50.20 V

Inverter DC restart voltage 51.00 V

Low DC alarm level 50.60 V

Do not restart after short-circuit (VDE 2510-2 safety) unchecked

enable AES unchecked

TAB: Charger

Enable charger checked

Weak AC input unchecked

Stop after excessive bulk unchecked

Lithium batteries checked

Disable VSense (for diagnostic purposes) unchecked

Configured for VE.Bus BMS unchecked

Charge curve Fixed

Absorption voltage 57.60 V

Float voltage 57.60 V

Charge current 35 A

Repeated absorption time 4.00 Hr

Repeated absorption interval 7.00 Days

Absorption time 4 Hr

TAB: Virtual switch

TAB: Usage

Virtual switch usage Do not use VS

TAB: Assistants

TAB: Assistant Configuration

Assistants not used

TAB: Advanced

limit internal charger to prioritize other energy sources unchecked




Multiplus-IIoffgrid
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4 Answers
Alexandra avatar image
Alexandra answered ·

@Urban caterpillar

Check if the VE bus SOC is synchronised with the Shunt SOC.

It is possible it is using internal only and it is not correct. It can't logically compare the voltage and SOC and choose which one is more correct.

In the GX in system setup make sure the shunt is the battery monitor. And also in system set up if the system status shows the synchronisation.

If you don't have a GX you will have to switch to using voltage only.

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urban-caterpillar avatar image
urban-caterpillar answered ·

Thanks Alexandra. I have set the shunt as the battery monitor on the GX settings monitor through the VRM portal. I'll check the system set up page in the GX settings to make sure it has synchronised. I'll let you know how it goes.

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urban-caterpillar avatar image
urban-caterpillar answered ·

I checked those settings via remote console and everything appears synchronised and correct. I re-sent the config file to the Multiplus last night and will wait and see how it performs today.

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Paul B avatar image
Paul B answered ·

nearly 100% your issue is that a battery cell voltage is going LOW - below its min BMS setting inside the battery. if you have a BMS that has bluetooth, check the CELL voltages . My bMS reports to the cerbo attached is a example. you can see here a cell thats collapsing - and yes I know its basically at 100% discharge but I am testing its full capacity. in this case the low cell causes the shutdown. (out of interest only these cells are 10 years old and have been cycled to 90% DDC every day and they still have there rated capacity.)


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