question

de1nonly avatar image
de1nonly asked

Minimum battery SOC increasing every day.

I have a Multiplus II GX 48/5000 with a BMV 700 battery monitor.


Every day the minimum SOC that the system will use keeps rising by ~2%

Can't embed photos to this post for some reason so here is a link:

https://photos.app.goo.gl/RaFXqRnVAgivykPD7


So a 3 days ago it would not discharge below 65%

2 days ago it would not discharge below 68%

1 day ago it would not discharge below 70%


ESS Optimise with battery life is on but the Active SOC Limit: is 20%.

Dynamic ESS is off.


Where should I start to troubleshoot the problem? Is there any other information that you guys need that would help?



Some maybe relevant information:

There was an issue just before with the battery % reading differently between the the BMV and Multiplus. That was rectified because the battery capacity was set to different values in BMV and Multiplus.

I keep getting

VE.Bus System [275] Low battery: Alarms throughout the evenings and mornings




Multiplus-IIBMV Battery MonitorSOCbatteryoperationallimits
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2 Answers
Alexandra avatar image
Alexandra answered ·

@de1nonly

Battery low warning may be from the dynamic cut off in the ESS assistant.

The ve bus soc should synchronise to the BMV.

Under system set up in the GX check what is set as the battery monitor on the system.

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de1nonly avatar image de1nonly commented ·

The Battery Monitor is set as the "BMV-700 on USB".

So the ESS sustain voltage is set at 48.5

Currently at 48.5V the battery SOC reads 75%

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So it looks like every day, the system uses the battery till about 48.5V and then hops on the grid as the ESS instructs it to. The system has been 48.5V, interpreting 48.5V as 63% one day, then 65% the next, then 68%, etc.

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Does that mean the SOC reading is off, or should I be setting my ESS sustain voltage lower?

In terms of the ve bus SOC synchronising to the BMV. Is that something that happens automatically when the Battery Monitor is set to the BMV?

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1234enough avatar image
1234enough answered ·

With battery life on, the system alters the Min SOC to try and maintain daily battery to 100%. Try with battery life off.

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