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teloth asked

VE.Bus System Charge state showing Bulk or Absorption in the middle of the night where no charging taking place , this causes SOC jump to 100% mysteriously , please see screens of VRM log download

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log1.jpgVE.Bus System Charge state showing Bulk or Absorption in the middle of the night where no charging is taking place , this causes SOC jump to 100% mysteriously , please see screens of VRM log download.

When it decides to get stuck in Absorption mode from day before and througout the night , it makes my SOC jump to 100% prematurely and when battery is nowhere near full.

This appears to happen every few days , sometimes once a week , sometimes twice a week , no exact or particular pattern.

Also , every single night charge state shows BULK , I can live this , even though it is obviously incorrect , but at least this does not make my SOC jump.

Jump only happens when it is stuck in Absorbtion mode.

Multiplus II GX 48 5000 , 3 x SmartSolar MPPTs , multiplus is running in inverter mode , no assistants.

Absorption voltage is specified as 55.65V and state of charge when bulk finished is definded as 95% in VE configure.

VE.Bus
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teloth avatar image teloth commented ·
Hello ?
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3 Answers
nickdb avatar image
nickdb answered ·

What batteries do you have and what BMS/BMV etc? If you have a shunt, what are its settings?

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teloth avatar image teloth commented ·

LiFePo4 battery bank with its BMS but this does not communicate directly with MultiPlus.

No shunt.

The only thing can determine the top state of charge is as per my original message.

" Absorption voltage is specified as 55.65V and state of charge when bulk finished is definded as 95% in VE configure. "

So , the only time SOC percentage adjustment is made within the system is when voltage hits 55.65V.

My main question is VE.Bus System Charge state , it is reporting Bulk state in the middle of the night etc. Where is it getting this information , there is nothing within the system that feeds this incorrect state " bulk " , this is where the problem is I am sure, State of Charge information is wrong somehow.

Have you looked at the VRM spreadsheet screenshots I uploaded?


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nickdb avatar image
nickdb answered ·

This environment will never work correctly, because (ESS) with MPPT's etc, the internal monitor of the multi is way too inaccurate, because it does not "see" all of the current flows on the DC end.

That would be fine if your BMS could communicate to the GX.

So you really need to put a proper shunt in to become the reference point, configured for your battery specs.

Without this, incorrect synchronisation can and will happen.

Maybe also post screenshots of the charger/battery tabs from veconfigure.

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nickdb avatar image nickdb ♦♦ commented ·
Just to add, are you off grid? Is that why you aren't using ESS?

Are all the mppt's connected directly to the GX and DVCC is enabled for coordinating charging and shared voltage sensing?

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teloth avatar image teloth nickdb ♦♦ commented ·
I am not off grid , but have big enough PV array and battery storage , so for many long months practically off grid , as I run Multiplus in inverter mode only.

I do not run or want to run ESS.

3 x MPPTs are connected directly to Multiplus II GX , DVCC is not enabled , No.

Can't remember why I decided not to enable DVCC at the time , but there was a reason , can't remember now.

I like to keep my setup as minimal and simple.

I don't particularly want overcomplicate things by adding / configuring stuff where they are not really need to be there.


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nickdb avatar image nickdb ♦♦ teloth commented ·
In this config DVCC is recommended and in most similar setups it is required.

A shunt (while costing some $) provides an accurate reference voltage, SOC and will be the Voltage reference for DVCC to use across all charging devices.

You can still use DVCC without one, using the multi as the source, but the internal sensor will still result in sync errors and inaccurate SOC, not because of a flaw but due to physics since it has zero visibility into anything happening between the mppt's and battery.

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teloth avatar image teloth commented ·

I did not say I use ESS, which I do not. Nor any other assistants.

I use it practically off grid , inverter only for 6 months and rest of the year with Virtual switch ignore AC input based on battery voltage and Load conditions.

System works perfectly as intented and configured , apart from the Multiplus somehow incorrectly deciding the put random wrong charge states itself , as nothing else in the system can feed this information to it.

I do not need or want to install a shunt , I don't need pinpoint accurate SOC % , but of course I do not want SOC jumping to 100% out of nowhere randomly without any obvious reason either.

My main question again , WHERE does Multiplus allegedly getting this Charge State information , and why it is showing clearly incorrect.

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nickdb avatar image nickdb ♦♦ teloth commented ·
Charge state is a red herring.

Without a shunt, without DVCC, without networked mppt's (not sure how you have networked these), without shared references you can only expect unexpected behaviour.

This is why they should be reporting external control as their state, with the GX managing the units behaviour based on a common, configured reference.

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teloth avatar image teloth nickdb ♦♦ commented ·

So , what you are saying is , Multiplus II literally generates a Charge State randomly and incorrectly out of the blue , without any device feeding this information directly to it ?


This is a fundamental flow , if this is the case.

Victron , can we get an answer please?

Is there a way to disable this Charge State thing ?

Easy to say add this , add that , fork out few hundred extra £££ , shunts , battery monitors , complicate wiring unnecessarily , to fix something that should not be happening in the first place.

Multiplus has technically a shunt / battery monitor , which is more than sufficient for basic needs.


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nickdb avatar image nickdb ♦♦ teloth commented ·
No, I am saying that your setup does not conform to best\recommended practice, you have been given plenty of advice across duplicate threads which you have chosen to ignore and instead argue about and subsequently blame the product.


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teloth avatar image teloth nickdb ♦♦ commented ·

Why does it not conform , because I do not or want to use ESS ?

In previous thread , there was pointless going off topic regarding my battery , which has nothing to do with this issue.

If Multiplus throwing random " Charge State " figures and making my SOC jump to 100% , sure, it must be all my fault... :-)

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nickdb avatar image nickdb ♦♦ teloth commented ·
No, has nothing to do with ESS. You aren't using DVCC so there is no central control of charge sources and no common reference for them.

You have chosen to not use a shunt so the system can never see all the energy flows and so is inaccurate and unreliable.

You have also chosen to use a battery that can't provide this information to the system.

Simplifying is good but you have simplified to the point of removing things the system needs to operate consistently.

That you have problems should be completely expected.

I am going to leave it here, there is little more to be said.


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marekp avatar image marekp teloth commented ·
@Teloth

Man take a deep breath and start to think about what @nickdb is trying to tell you.

Draw yourself a BIG diagram of your system and maybe than you will see that MP does not have all the information on the energy coming and going to and from your battery.

In short, you get "crap" (SOC) from MP because you put "crap" into it.

At the end, using voltage of the LFP battery as a indicator of its SOC is irresponsible.

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teloth avatar image teloth marekp commented ·

" Man " , your reply shows me that you still do not understand what the main question is as my original post , along with what the spreadsheet is displaying.


Multiplus DOES know what is coming in and going out , as this works for most of the time and shows correct SOC% , until Multiplus decides to make it jump to 100% , because of this incorrect charge state.

Question is , as above , " WHERE does Multiplus allegedly getting this Charge State information , and why it is showing clearly incorrect. "

Do you have the answer?


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marekp avatar image marekp teloth commented ·

@Teloth

Read this:

https://www.victronenergy.com/media/pg/VE.Bus_Configuration_Guide/en/description-of-settings.html

You are intelligent man.

You will get it.

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teloth avatar image teloth marekp commented ·

Already read that along with many other docs, there is nothing in there that explicity state an explanation to what I am asking.

So , in other words , translation of your post is you don't know the answer ,yet , you appear to lke clicking the answer button when making posts , you should use the " comment "button instead.

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marekp avatar image marekp teloth commented ·

So for example at 48V, the re-bulk mechanism for a lithium battery will use Vfloat - 0.8V with a maximum of 54V.

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marekp avatar image
marekp answered ·

@Teloth

It is your second attempt to ask this question.

Obviously you did not like the answers the first time.

What make you think that this time will be different?

https://community.victronenergy.com/questions/142695/multiplus-ii-gx-5000-soc-jumping-to-100-with-no-re.html

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teloth avatar image teloth commented ·

Yes, because I have a clearer idea what is exactly causing the issue , hence this post with more precise information and evidence as per screenshots of Multiplus " Charge State " behaviour.

Secondly , it wasn't the case " I did not like " the answers in previous , the so called " answers " in that thread was not answers but you and someone else talking about my battery might be causing the issue , which clearly has nothing to do or cannot have anything to do with it.

As you probably realise now this is not battery itself issue. My battery bank is perfectly fine ...

Unfortunately , perhaps you did not understand exactly what I was talking about in that thread and going on about something totally irrelevant , remember?

" What make you think that this time will be different? " , well , I am asking more precise question , so the answer should be different , if questions are understood correctly.

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