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andrewcp avatar image
andrewcp asked

Strange MPPT - charging stopped

Hi,


I have a Cerbo gx, bmv712, and two Victron MPPT’s…

This install was stable for over two years… Charging and maintaining things in my caravan without issue… until recently.

I have:

- the bmv, and two mppt’s connected via ve direct cables to the Cerbo gx.

- the Cerbo gx is just monitoring Everything, and I use it for vrm logging.

- the two mppts and bmv are in a smart network to control charging


What I have recently found is that the mppt’s will sometimes not resume charging… even though they show as being in bulk mode… there is zero amps going in, and the voltage is well below the maximum…

this is new behaviour and started a couple of months ago…

I am not sure if it is as a result of a firmware update on the Cerbo, bmv, or mppt’s…


thoughts?

cerbo gxMPPT SmartSolarBMV Battery Monitor
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4 Answers
seb71 avatar image
seb71 answered ·

Not sure about the cause, but with a Cerbo and a BMV in your system you should disable VE.Smart Networking and use DVCC in Cerbo instead.

Set the BMV as Battery monitor in Cerbo (System setup menu).

Enable DVCC, Shared Voltage Sense, Shared Current Sense and - if you have a temperature sensor connected to BMV - Shared Temperature Sense.


What battery you have? Lead-acid or LiFePO4?

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andrewcp avatar image andrewcp commented ·
240ah LiFePO4… which is now 10 years old…


it’s interesting one of the mppt’s is showing gaps in the data in the Cerbo… I suspect the ve direct cable isn’t happy!

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kevgermany avatar image kevgermany ♦♦ andrewcp commented ·
Try replugging it a couple of times. If that doesn't help, might be time to replace the cable
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uguraladag avatar image
uguraladag answered ·

Your mppt stops charging when your battery is full. Besides, if you have a temperature sensor in the system, disable the temperature compensation and low temperature cut-off feature.

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andrewcp avatar image andrewcp commented ·
SoC was at 84%… voltage at 13.2v(cutoff voltage 13.4v), both mppt’s were in bulk mode according to their Bluetooth status and with battery and pv voltage, but 0 amps…
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kevgermany avatar image kevgermany ♦♦ andrewcp commented ·
Battery SOC readings depend on the BMV settings. The BMV and BMS can have completely different ideas about SOC.
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andrewcp avatar image
andrewcp answered ·

What I did find… was taking the mppt out of the smart network, then the charge Resumed.

next time I will drop the bmv out of the smart network first and see if the mppts start charging again.

I now have an alarm on the vrm site to email me if no charge(w) is received on either mppt for 24hrs… so hopefully I will be alerted before it runs the battery down to the lv alarm.

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kevgermany avatar image kevgermany ♦♦ commented ·
Smart networks and VE.direct are not compatible. While it may work if both are used, it's not supported and may suddenly give problems. @Seb71 has already said it should be disabled.
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andrewcp avatar image andrewcp kevgermany ♦♦ commented ·
Can you please provide a link to where this is mentioned?
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Cristian avatar image
Cristian answered ·

https://community.victronenergy.com/questions/203617/mppt-displays-negative-temp-and-stops-charging-eve.html?childToView=225106#answer-225106

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