question

edgargw22 avatar image
edgargw22 asked

System shuts down - low voltage at ~50% SOC - why so early?

My Victron system shuts down with low voltage at 50% SOC - why so early?

I installed a Victron system last summer and it seems to shut down at around 50% SOC. I thought it was supposed to be more like around 20-25% SOC. I'm pretty happy with the overall performance, but wish the SOC was more accurate. Any ideas? TIA.

I have the following equipment: Two Victron 12,8 LFP batteries w/Bluetooth (each 300 Ah), Victron MultiPlus 12/3000/120-50 120V VE.Bus Inverter/Charger, Victron Battery Monitor BMV-712, Victron Color Monitor w/Bluetooth dongle and Victron Smart Solar Charge Controller MPPT 150/85-Tr.

BMV Battery Monitor
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4 Answers
Tom avatar image
Tom answered ·

Just to help other reply to your question, you may want to post a screen shot of your inverter and charge setting in the Victron Connect.

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edgargw22 avatar image edgargw22 commented ·

Good idea. I will post a screen shot tomorrow. Thank you!

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edgargw22 avatar image edgargw22 commented ·

Hey Tom, see the screen shot that I just posted above. Thoughts?

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Tom avatar image Tom edgargw22 commented ·

I don't know much about your batteries but the low voltage shutdown is preset at 2.5v volts x 4cells =10 volts. You may possibly lower you shut down from 10.5 volts to 10.25 volts, but you should question your installers about your issue.

Do you have a Victron Battery protect installed? What are the setting for that?

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Justin Cook avatar image
Justin Cook answered ·

@Edgargw22, you can set the low-voltage shutdown parameters yourself; if you have the requisite MK3 to USB Adapter for configuring your MultiPlus using a PC, you can find this setting in the VictronConnect app by connecting to your Multi, opening the Settings menu, and going to the "Inverter" settings... see the attached screenshot of it pulled up on a demo product.

Be advised that you cannot program or change settings via Bluetooth; you need to either be connected to a PC using the MK3 to USB adapter or a phone using the same adapter plus whatever adapter you need to convert from the USB-A connector on the MK3 adapter to your phone's USB connection.


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edgargw22 avatar image edgargw22 commented ·

I do have the MK3/USB adaptor and will take a look at it tomorrow. Thank you!

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edgargw22 avatar image edgargw22 commented ·

Hi Justin, here's a screen shot of my VEConfig utility, specifically the Inverter tab. Thoughts?

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Justin Cook avatar image
Justin Cook answered ·

@Edgargw22, I'd use VictronConnect rather than VE.Config just to compare, as the VE.Config's SOC shutdown feature is actually elsewhere, and I forget where exactly.

The settings I see above all seem about right, and depending on what you see in VictronConnect (on your PC, of course, connected through the MK3 still) I'm actually wondering if it might be that your BMV isn't wired or configured correctly. The Multi is not innately measuring SOC, it's relying on the BMV to report that data to it, so if -for instance- your BMV isn't configured properly to your battery bank's total Ah capacity, it would be reporting an SOC to the Multi that is inaccurate... thus triggering the Multi to shut down earlier than it should because its SOC shutdown is a function of the data that the BMV is reporting to it.

So:

Connect to your Multi through VictronConnect, using the MK3, and check the "SOC shutdown" settings as I showed in my screenshot. If that seems like it's set correctly, then go out to your BMV over BT on your phone and make sure your battery bank capacity is set correctly. If both of those things are set correctly, then double-check your wiring at the BMV shunt, making sure that ALL loads and charger negatives are connected to the "load" side of the shunt... it's possible that the BMV is reporting a low SOC because a charger is bypassing the shunt, which makes it invisible to the BMV.

If all that is five-by, then I'm currently fresh out of ideas...

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edgargw22 avatar image edgargw22 commented ·

Hi Justin, you make a really good point about tracing all wiring through the shut. I will check that over the next few days. If I remember correctly, there are a few items that don't go to the shunt, like the BMV-712 panel (I wanted that to operate even if the BMV shut down the system).

Here's some screen shots from my phone via VictronConnect looking at my BMV-712 Smart. Is there information that's still missing that I would get by connecting my laptop via the MK3 and loading VictronConnect onto the laptop? Thanks again!

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Justin Cook avatar image
Justin Cook answered ·

@Edgargw22, sorry I missed your reply... without the "@" tag it's easy to lose track of what threads I'm on.

In re to your question, your above screenshots are showing the BMV-712 in VictronConnect, and all those settings look -at a glance- correct, though I note that the low-SOC alarm is set to 50%, which I think is likely to be the source of your problem.

I still suggest that you connect to your Multi using an MK3 to USB adapter and load it into VictronConnect where you can then easily check whether or not the low-SOC shutdown is enabled on the Multi. Your BMV is set to alarm at 50% SOC, so I wouldn't be surprised to find that your Multi is configured to shut down when the BMV alarms... which would neatly explain your Multi shutdown at ~50% SOC.

Alternatively, you could connect to your BMV and change the low SOC alarm setting to something like 30% (or whatever you want) and see if that changes the behavior of your Multi... if it does, then we've identified your problem.

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