Lynx Shunt + Multiplus II - Shutdown on low SOC without MP II battery monitor

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gianmarco asked Jul 29, '23

Lynx Shunt + Multiplus II - Shutdown on low SOC without MP II battery monitor

Good morning everybody.

I'm here asking you some hints about configuring the MP II in an OR logic, to shutdown if low voltage is reached OR low SOC is reached.

I already set up the voltage limitations, but I'm struggling to make the shutdown on low SOC to work.

That's because I'm not using the MP II as battery charger (to charge the batteries I'm using two RS450|200) so I don't want to enable the internal battery monitor. The only battery monitor I want to use is the Lynx Shunt.

The problem is that if I try to enable the Shutdown on low SOC in VE.configure it tells me that I must enable the internal battery monitor.

Is it possible to make the MP II read the SOC from the Lynx Shunt and setup the shutdown on low SOC without enabling the internal MP II battery monitor?

Thank you for your time, have a nice day.

EDIT: I have a Lynx shunt because I'm using Opsz lead-acid flooded batteries.

Here are some photos of the installation:

Multiplus-II SOC lynx shunt low battery warning shutdown

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Modifications Space

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Answer 1 · 2023-07-29T12:07:11Z

victech-power answered · Jul 29, 2023 at 12:07 PM

Although I do not have an immediate answer to you question and I also am not read in to your configuration. I would like to provide some extra input for helping your case.
We install lots of ESS systems where there is NO shunt but a BMS-CAN connection to a battery stack.
The BMS-CAN connection is providing same info as the shunt which is battery SOC.
In case of CAN , you also get the battery details so you do not have to set it manually.

I cross checked some of the systems installed but they all have the battery monitor enabled.
I also noticed that one of the systems that had a battery added was properly informed by the CAN that now not 400Ah was available but 500Ah.
So I have a config difference where this leads me to believe that the CAN-BMS setting overrides the setting in VE.Configure.

Perhaps in your case too , but test it.

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gianmarco commented · Jul 29, 2023 at 02:39 PM

You're right: I didn't specify that I'm using Opsz batteries, that's why I need the shunt. No bms here.

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Answer 2 · 2023-07-29T12:52:49Z

Alexandra answered · Jul 29, 2023 at 12:52 PM

@gianmarco

I assume you also have a GX in your system....

If so, enable the internal battery monitor. Then on the GX set the lynx as the system battery monitor in system set up. The VE BUS SOC actually synchronises to the lynx monitor SOC anyway with the GX in the system.

Then all your desired features and options will work and work correctly according to the lynx.

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gianmarco commented · Jul 29, 2023 at 02:41 PM

Hi Alexandra, thank you for your suggestion.

So, if I enable the internal battery monitor on the MP II and tell the Cerbo gx to use the Lynx Shunt monitor it's guaranteed that the MP II will read the SOC only from the shunt?

I really don't want to mess this up. Thanks.

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Alexandra ♦ gianmarco commented · Jul 29, 2023 at 06:17 PM

@gianmarco

That is correct. Now you just need to make sure the shunt is correct....

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gianmarco Alexandra ♦ commented · Jul 29, 2023 at 07:53 PM

Thank you, you asked a giant question in my head. The shunt is set up perfectly and reads the SOC with precisione even if I'm using OPSZ batteries.

Thank you again for your time.

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