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abegweit avatar image
abegweit asked

Using BMV712 SOC to trigger Multiplus DC Input Low Shutdown without GX Device

Hi I'm looking for some help to understand the best way to trigger the DC Input Low Shutdown on my MultiPlus 3000VA from the BMV712.

I am off grid, solar charging Lithium Smart batteries with an MPPT 100/50, and use a small inverter generator to feed the MultiPlus when solar charging is insufficient.

I would like to limit battery discharge to 15% to maximize the life of the lithium smart batteries.

I've tried tuning the DC Input Low Shutdown voltage settings in the MultiPlus but found too much variability in the actual SOC when the DC Input Low Shutdown is triggered. For example, when a relatively short duration, heavy AC load is applied to the MultiPlus, the DC voltage will drop, triggering the DC Input Low Shutdown at a SOC much higher than if a small continuous AC load is being fed by the MultiPlus.

Attempts to use the battery monitor function of the MultiPlus and the corresponding SOC functionality to trigger shutdown did not work because the MultiPlus SOC is not accounting for the MPPT charge current.

Thank you

MPPT ControllersMultiPlus Quattro Inverter ChargerBMV Battery MonitorLithium BatterySOC
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2 Answers
Ian Jordan avatar image
Ian Jordan answered ·

I guess you could use the relay output on the BMV as a trigger. Then connect that output to one of the aux inputs on your Mulitplus and use the two signal BMS support assistant. This has the option within it to use a single signal for low battery that changes the Multiplus to charge only.


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abegweit avatar image abegweit commented ·

Thank you jordash184. I am using the VE.Bus BMS Support assistant to manage the MultiPlus configuration for the lithium smart batteries. Do you know if I can also use the two signal BMS support assistant while the VE.Bus BMS Support Assistant is in use?

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Ian Jordan avatar image Ian Jordan abegweit commented ·

Unfortunately not, I just tried using a demo system on VE Config and it won't let you do it. Unfortunately I don't think you can do this without a GX device. It's easy enough with GX as you can select 'Synchronize VE bus SOC' I think.

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klim8skeptic avatar image
klim8skeptic answered ·

Given ur OP, bite the bullet and buy a venus device (and cables etc,,,)

Batteries are MORE expensive, vs the cost re monitoring ur system.

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abegweit avatar image abegweit commented ·

Thanks for the suggestion. I am at the front end of a steep learning curve. If you can recommend a Venus device and how I would use that to disable the inverter based on BMV712 SOC that would be really appreciated.


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