Pylontech SOC 98% . Not 100%

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Herve RV Nizard asked Aug 31, '22

Pylontech SOC 98% . Not 100%

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Victron MII 48/5000 GXImage Caption

Smart solar 250/100

2 x Pylontech UP5000Image Caption

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5 kwp of panelsImage Caption

no battery monitor

installed a few days ago.

for unknown reason , does not go back to 100% SOC. Stays at 98%.

Charging only via solar. off grid

plenty enough sun to charge more if needed.

all relevant pylontech settings done on smart charger but it does not mean much as pylontech BMS takes over ( external control).

As a result, I notice a cell imbalance when fully charged.

and see charge is mainly bulk, no absorb, little float

So I don't know where to change something to improve the situation and make sure the system goes back to 100% SOC....

Any idea

MPPT Controllers Pylontech SOC

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Modifications Space

Node Red Space

Answer 1 · 2022-08-31T17:07:20Z

nickdb answered · Aug 31, 2022 at 05:07 PM

For a new pack thats normal. It needs to balance. Off grid makes this more difficult as it needs time and usually on grid you could set it to keep charged.

Just let it be and try leave it at full charge as long as possible.

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Herve RV Nizard commented · Aug 31, 2022 at 06:47 PM

among all the similar systems we installed, it's the only one doing that. There is plenty solar power available for a very little consumption for now. strange....

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alaskannoob commented · Sep 20, 2023 at 04:56 AM

@nickdb do you know how it balances? I have 8 newly installed US5000 off grid and I have each of them wired directly to the bus bar. They are networked with RJ45 but otherwise have no other cables connecting them to each other (other than the bus bar being a common connection).

Do I need to use the small positive and negative cables to connect the batteries to each other for them to "balance?"

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Answer 2 · 2022-08-31T20:23:51Z

Alexandra answered · Aug 31, 2022 at 08:23 PM

@Herve RV Nizard

On the mppt, use the preset lithium, then tweak the voltages. The charge profile there has equalization and temp compensation. So not set up totally right.

The system if it is BMS controlled will onky charge when told to do so. And on some systems the Pylontec batteies keep themselves at 98 or 99%. Especially when "floating".

Have you followed a the required settings on the pylotec victron page for the basic offgrid?

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Answer 3 · 2022-08-31T23:46:20Z

Herve RV Nizard answered · Aug 31, 2022 at 11:46 PM

Hi @Alexandra . thank you.

yes i followed all the victron / pylontech settings. We do install many of the configurations with Victron + Pylontech UP5000. ALL the others go to 100%.

for the mppt settings , I generally do not use the lithium preset because absorb and float are far hugjer than what pylontech requires. but anyway as you mentioned, with the pylon to victron datacable to the gx , the pylontech bms takes over.

the equalization is part of the page but off of course.

what i don't like is that due to this, i notice a larger voltage difference between cells when charging. it does not seem to balance the cells .....

i am closely following it...

thanks anyway for your input ; appreciate

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nickdb ♦♦ commented · Sep 01, 2022 at 05:55 AM

I've seen them do exactly the same thing, just on grid. It will continue to slowly charge while the gap between cells narrows.

It just depends how unbalanced they were when you got them, they don't all ship the same. a few days isn't a long time.

That isn't a particularly big cell difference.

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Answer 4 · 2022-09-01T06:28:01Z

nickdb answered · Sep 01, 2022 at 06:28 AM

It is normal, as per manuals.

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