question

eham avatar image
eham asked

DVCC and MPPT 450 RS ext.control

HI


MPPT 450 RS (VE.Can) are in ext.control but the MPPT will not listen to the Multiplus/Cerbo or itself regarding the charge curve.


I have two ea. Multiplus-II 5kVA in parallel, Cerbo GX, Lynx Shunt, Lithium-ion battery with standalone BMS, MPPT 450 RS 100 and MPPT 450 RS 200. All devices is updated to latest Firmware.The system is set up with ESS and VDE Grid-code. In VE Configure I have selected “System uses LiFePo4 with other type BMS”


With the DVCC enabled the MPPT 450 RS are in the ext.control State. When charging the batteries, the Multiplus follows his parameters regarding bulk, absorption and float. But the MPPT’s keeps full charge and will not stop before I turn the MPPT off in the VictronConnect APP.

It uses SVS and the Lynx Shunt as battery monitor and BMS control is OFF.


All VE.CAN devices have the same Device ID and there is no errors or losses on the VE.CAN communication. The MPPT 450/100 is Group master and the MPPT 450/200 is Slave.


DVCC SCS is “Disabled (External Control)” and under System Setup the “Solar charger Current Control: OFF”

dvcc.jpgsystem-setup.jpg

or

Could these two setting be the reason for this strange behavior?

Any troubleshooting ideas are most welcome.

MPPT ControllersDVCCmppt rs
system-setup.jpg (19.4 KiB)
dvcc.jpg (23.2 KiB)
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3 Answers
Alexandra avatar image
Alexandra answered ·

@eham

How DVCC is used to controll the system depends on the battery.

If they are not smart (such as yours being stand alone) then the mppts follow the charge profile ans voltages you set on them with their own charge algorithm.

To some degree they are controlled by the max battery charge current in DVCC.

Check that the system is set the same on all devices, and they are all reading within 0.3v of each other.

The mppts in an ESS system will produce even when the batteries are full to support house loads. So ideally you don't want them to stop producing.

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eham avatar image eham commented ·
The MPPT and the Multiplus has the same charge settings. The problem is that the MPPT charge voltage does not stop at Absorption voltage, it keeps going at full charge current. The absorption voltage is set to 56,7 VDC and I had to manually turn it off at 57,1 VDC and it was then charging the batteries with 250 A.
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Alexandra avatar image Alexandra ♦ eham commented ·

@eham

Do you have anything like temp compensation or equalisation set?

Are you feeding back at all? if so then expect the 0.4v higher.

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fifman avatar image
fifman answered ·

Hello,

I have the same problem,


System:

3phase (2x MP5000 parallel)

1x MPPT 450/200

1x MPPT 450/100

The MPPT RS is not stopping to charge.

DVCC : aktiv

SVS: aktiv

SCS: aktiv


Is there a solution yet?

Thanks

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eham avatar image
eham answered ·

Hi.

I switched communication from VE.Can to VE.direct and everything works as it should. The MPPTs 450 are now listening to the charge settings of the Multiplus.


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beat avatar image beat commented ·

This is a very interresting finding! @Guy Stewart (Victron Community Manager)


I'm wondering if that would be related to my different but also MPPT RS 450/100 overcharging issue here https://community.victronenergy.com/questions/229525/excessive-battery-solar-charge-current-when-big-ac.html as I also use Victron CAN bus between Cerbo GX and MPPT RS 450/100.

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beat avatar image beat beat commented ·
I have tried using VE-direct instead of VE.CAN and see no difference in from time to time with the RS 450 not following, during several long minutes, the maximum charge current given by BMS. And that even when already charged at 100% and with battery size following recommendation.
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