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davidtudor avatar image
davidtudor asked

Charging 3 Phase Multipluss ii

Hi,

I have 6 x Multipluss ii 5000KVA on a 3 phase off grid system with 27 solar panels and 3 phase 21KVA generator, when the generator is running at full load we get around 18kw from it and it will run a 10kw house usage and also charge the batteries around 100amp, i have 10 Pylontech batteries mixture of US5000, US3000, US2000. total of around 35KWH.

When no load is on the AC and the generator can use full power to charge the batteries via the Multipluss ii, i am only getting maximum 250 amp charge, 3 of the Multiplus are slaves, and i suspect they don't charge? Otherwise i am thinking the total rate of all six charging would be 6x70 420amp charge? Is this right? i know the batteries will take it as the Pylontech say they will take 500amp charge and i know i have had a 400amp discharge when our car is charging, via invertors and batteries.

Multiplus-IIPylontech3 phasecharge current limit
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3 Answers
duivert avatar image
duivert answered ·

hi what do you mean with 3 are slave?

If the pylontech’s are correctly wired and setup, the bms controls the maximum charge rate not the multi’s

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davidtudor avatar image davidtudor commented ·
Yes the BMS pylontech controls the charge, but why is it so low?
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duivert avatar image duivert davidtudor commented ·
Maybe it depends on the SOC, i have 3x us5000 and they charge with about 40-50 amps max on 3 phase multiplus 2 3k at a 50-40% SOC while the mps can deliver a max of 105A
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davidtudor avatar image davidtudor duivert commented ·
Probably mine is OK the at 250amp charge
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davidtudor avatar image
davidtudor answered ·

Hi

3 of the Multipluss are classed as slaves.

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Alexandra avatar image
Alexandra answered ·

@davidtudor

Did you leave them at 70A on the MP2 default in settings when programming.

Confirm you do not have ESS assistant loaded?

Is weak AC enabled?

Do you have a GX? Confirm the Charge current is not capped in DVCC.

Is the input current limit up where it should be?

Validate your some inverters are not contributing to the charging theory with a DC clamp meter to check them.

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davidtudor avatar image davidtudor commented ·
HI

I have no ESS, weak AC is enabled, i have a GX. I need to check other settings.

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davidtudor avatar image davidtudor davidtudor commented ·

dvcc.png

DVCC

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dvcc.png (32.6 KiB)
Alexandra avatar image Alexandra ♦ davidtudor commented ·

@davidtudor

It is partly an side effect of the weak AC. With that setting you definitely will not see the full 70A. Closer to 45/ 50A depends on the installation internal temperature as well.

(Derating on temperatures there is a section on it in the manuals about it)

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Alexandra avatar image Alexandra ♦ Alexandra ♦ commented ·

And some further quick calculations.

21kva generator at 80% load is 16kva which is optimal for gensets (Assuming you are at sea level so no derating for altitude.)

At 18kva you are working it a little hard.

30A per phase can be drawn - technically that is 140A to charge per phase assuming a 1:1 and zero loads on the AC out.

I think your charge rate for the generator size is ok. And the loads you are running at the time.

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davidtudor avatar image davidtudor davidtudor commented ·

parameters.png

Parameters

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parameters.png (36.3 KiB)
duivert avatar image duivert davidtudor commented ·
Thats what the pylontech bms tells the system, but that doesnt mean it always charge with those amps…


It probably is what @Alexandra posted

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Alexandra avatar image Alexandra ♦ duivert commented ·
In short your generator cannot charge at that rate and run your loads at the same time. It is too small.
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davidtudor avatar image davidtudor Alexandra ♦ commented ·
Yes i agree, just wanted some clarification
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