question

jolilo avatar image
jolilo asked

Tail current 3 MPPT

Hello everyone

I have three MPPT 150/32 2BS and 1 SS chargers

in // on a 48v battery

connected to a multiplus II

my question how the tail current works because I noticed if I programmed a threshold at 2A on each one it is the first one which goes below the threshold which forces the SOC to 100%

but there are three MPPTs in // therefore the load is still higher than the threshold and distorts the SOC

how to do it thank you

I deactivated the three tail currents

now it's worse! I can't even determine who or what is calling the SOC

how to do it thank you

Need help2023-11-29-18-48-29-victronconnect.png2023-11-29-18-50-04-victronconnect.png

SOC
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5 Answers
Alexandra avatar image
Alexandra answered ·

@jolilo

Do you have a shunt to measure SOC?

Are the batteries communicating with the Cerbo?

If the battery is not, then each MPPT will be doing its own thing.

In system set up under settings what is set as the battery monitor?

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jolilo avatar image
jolilo answered ·

thanks for the help


Do you have a shunt to measure SOC?

no


Are the batteries communicating with the Cerbo?

no


If the battery is not, then each MPPT will be doing its own thing.

how to synchronize the 3 MPPT

In system set up under settings what is set as the battery monitor?

2023-11-29-19-41-03-terrabos-vrm-portal-maxthon.png view the photo


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jolilo avatar image
jolilo answered ·

2023-11-29-19-59-30-2023-11-29-19-52-13-terrabos-v.pngSOC jump detail


2023-11-29-19-59-30-2023-11-29-19-52-13-terrabos-v.png (22.6 KiB)
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Alexandra avatar image Alexandra ♦ commented ·

The inverter SOC when bulk is finished is likely at 95%. The ve bus SOC is more of a calculation and when there are other charge sources it is not accurate. Will also be made worse by the sudden tail current drop.



You need a Shunt for more accuracy.

Set up each MPPT as if they are stand alone, so they can charge correctly.


All sources should have the same voltages set. Check that they all read correctly as well.

Tail current is whatever it takes to get the cells balanced.

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jolilo avatar image
jolilo answered ·

Hello, Alexandra.

and thank you

I wanted to save on a shunt

state of charge at the end of the bulk phase is set to 92%

you can see it clearly in this image

and we can see very clearly the second jump of SOC

2023-11-30-12-59-58-terrabos-vrm-portal-maxthon.png2023-11-30-13-04-28-ve-configure-3-multiplus-ii-48.png

another question how to bring up a topic

I had a question that remains unanswered


https://community.victronenergy.com/questions/197660/colors-widget-are-not-respected-on-the-display-why.html?childToView=240809#answer-240809





2023-11-30-12-59-58-terrabos-vrm-portal-maxthon.png (36.6 KiB)
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JohnC avatar image JohnC ♦ commented ·
Hi @jolilo

I'm curious. You haven't mentioned your battery type, but you have a fixed 30m Absorption duration set. That suggests Li batteries given the 30m to balance their cells. And your V's don't match typical Pb's. Li's are usually considered very close to full when they reach Abs.

So if they are Li's, you shouldn't be using that Tail function anyway. And your Multi's SOC setting when Bulk stage is over should be up near 100%.

If you want to bump that other question, just add another comment asking again. I thought that was all fixed, mine was but it took a while. Might be platform/browser related, so provide more detail. Or you could try rebuilding a fresh widget.

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Alexandra avatar image Alexandra ♦ JohnC ♦ commented ·

@jolilo

It would seem your battery when bulk is finished would.be closer to 98% then not 92%.

If you say it is 98% efficient then in theory that is when bulk is finished.

The jump up in soc after the tail current and voltage is reached suggests that anyway.

For our interest where did the 92% figure come from?

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jolilo avatar image
jolilo answered ·

Good morning, John

thank you for your

it's a lifepo4 battery

I want to use the queue function

but I have 3 MPPTs in parallel and that's my problem, it's the first one that goes below the threshold that blows up the SOC


I tried in two different browsers and it's still the same for the color problem

however the edition is good2023-11-30-14-26-50-maison-monteils-vrm-portal-moz.png


2023-11-30-14-26-50-maison-monteils-vrm-portal-moz.png (25.4 KiB)
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