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Flemming Jacobsen avatar image
Flemming Jacobsen asked

Victron voltage miss alignment?

ee900076-f75d-42d7-8350-7bce65f47c61-1-all-1329.pngI have a installation consisting of:

Cerbo GX

MPPT 100/50

Smart shunt 500A/50mV

Phoenix inverter 12/1200 230

Wire with 35 m3 between units (16 m3 from MPPT to bus)

540W of solar panels

Connection Ve-direct


The voltage on the inverter is registered around 0,17V higher than on the rest of the units, and the charging cycle is being disturbed by that information, hence activate the absorption a bit too early and lowering the SOC, despite the fact the system is set to use the information from smart shunt and everything is connected via ve-direct, even the batteries show the “right” voltage. It only happens when the inverter is in “eco” or “on”. Any suggestions or fixes?

voltage
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Alexandra avatar image Alexandra ♦ commented ·

The inverter is not a charge source. Neither is it the controller of the system charge algorithms. That is the job of the cerbo. The voltage readings at its terminals have no effect on charge or charge algos.

Possibly on discharge it could over discharge by 0.17 of a volt. So don't be marginal with cut off.

You are measuring there with no current flow. I would be more concerned with voltage differences when under load.

In any case as already suggested DVCC is the answer with the shunt set as the battery monitor.

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pwfarnell avatar image
pwfarnell answered ·

Assuming you have lead / AGM / gel type batteries as you have not stated this, you need to go into Cerbo settings enable DVCC and then turn on SVS and SCS using the SmartShunt as the source. Yoy should also have the SmartShunt set as the battery monitor in system setup. If you have a battery temperature sensor then also activate STS and choose the sensor. Then all equipment will use the SmartShunt voltages and current readings, not their own value. See the manual.

https://www.victronenergy.com/media/pg/Cerbo_GX/en/dvcc---distributed-voltage-and-current-control.html

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Flemming Jacobsen avatar image Flemming Jacobsen commented ·

Thanks for the information, sorry for the miss. I've got a couple of lifepo4 12V 100Ah.

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pwfarnell avatar image pwfarnell Flemming Jacobsen commented ·

@FLEJ01 If they are drop in batteries and do not communicate with the Cerbo GX then using the SmartShunt for DVCC will still work. Some batteries that communicate with the Cerbo GX do not allow the SVS and SCS functionality.

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Flemming Jacobsen avatar image Flemming Jacobsen pwfarnell commented ·

Thanks. I'll try to fix the functionality, using your suggestions. However is there anyway to fix the poor reading from the inverter?


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pwfarnell avatar image pwfarnell Flemming Jacobsen commented ·

I have no idea if the Multiplus can be recalibrated.

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Flemming Jacobsen avatar image Flemming Jacobsen Flemming Jacobsen commented ·

Sadly the suggested fix, using DVCC, didn't work, my installation still goes into absorption about 0,5 % to early, and the voltage between units is still off with about 0,17v. The installation measures correctly when its inverting, and when the Inverter is in off.1000000194.png

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Alexandra avatar image Alexandra ♦ Flemming Jacobsen commented ·

You could always adjust the mppt. 0.1v higher.

Your shunt could also possibly not be synchronising correctly

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Flemming Jacobsen avatar image Flemming Jacobsen Alexandra ♦ commented ·

Well it still wont fix the issue of why the measurement on the Inverter, interfeers with the charging cycle, it should not as it has nothing to do with charging, its a consuming unit, furthermore the measurement is correct when it is inverting 12v dc to 230v af.

Thanks for your inputs.

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