Daly Smart BMS stops charging randomly

[Freeman656]

Which one do you have?

No charge controller, the solar panels use microinverter which are connected in my main board.

I've changed the setting of the BMS as you mentioned earlier.
Lets see tomorrow how it goes, I've also reduced the max charge current on the GX from 3k to 2k. I'm not at home so wont be able to restart the BMS anyway but I'll keep an eye on the VRM.

 

[John Frum]

@Freeman656 have you verified that your cell voltages as measured by your BMS agree with your reference multimeter?

 

[Ampster]

It's taken by the smartshunt on the MP connectors.

Then that is the inverter voltage and would confirm the spike when the BMS disconnects from the battery. There has to be a setting somewhere that causes the voltage to rise to 58 volts when the inverter is disconnected. When the battery is connected, the battery voltage is what will show up at the point in the circuit. Reducing the charging current will only delay when the BMS will eventually cut out since it will take the battery longer to rise to the cutoff voltage .Raising the cutoff voltage in the BMS will also delay the issue but not solve it. I still see it as a setting issue in your inverter. The title of the thread states the symptom, but disguises the issue as a BMS issue, when in reality the BMS is doing its job.

 

[John Frum]

Then that is the inverter voltage and would confirm the spike when the BMS disconnects from the battery. There has to be a setting somewhere that causes the voltage to rise to 58 volts when the inverter is disconnected. When the battery is connected, the battery voltage is what will show up at the point in the circuit. Reducing the charging current will only delay when the BMS will eventually cut out since it will take the battery longer to rise to the cutoff voltage .Raising the cutoff voltage in the BMS will also delay the issue but not solve it. I still see it as a setting issue in your inverter.

The inverter's charge profile must be within the safe voltage envelope of the BMS.

 

[MisterSandals]

It's taken by the smartshunt on the MP connectors.

This seems odd. Shouldn't the smarthsunt sense wires be on or as close as possible to the battery for a more accurate battery voltage reading?

 

[Ampster]

The inverter's charge profile must be within the safe voltage envelope of the BMS.

Yes, that is what I think should happen. I do not know enough about Victron equipment to help the OP find the setting on that inverter that is causing the problem.

 

[Luxpower_Gilbert]

Your set up is ac couple? What inverter are you using? Does your inverter can shift frequency to reduce power or disconnect your ac couple system?

 

[Freeman656]

@Freeman656 have you verified that your cell voltages as measured by your BMS agree with your reference multimeter?

Not yet, I'll check...

This seems odd. Shouldn't the smarthsunt sense wires be on or as close as possible to the battery for a more accurate battery voltage reading?

The cable between the MP and the battery is around 1m and the SmartShunt is in between the two, nearly at the center, so shouldn't matter so much.

Your set up is ac couple? What inverter are you using? Does your inverter can shift frequency to reduce power or disconnect your ac couple system?

AC Coupled yes. Inverter is APS DS3 micro inverters. I don't know about frequency shifting, but the inverters are not connected to the MP directly and there is no communication between the two. Check the attachement, I don't see the solar panels on the VRM because the current sensor is only on the main grid cable. It would need some additionnal ET112 to measure the solar, but I don't need it.

So, for today, I had no voltage spike, I don't know if it's a lucky day or if the parameters I changed were misconfigured earlier. (BMS settings and max current set to 2kW).
Tomorrow I'll go for 3kW of max charge current to see what is happening.
Either way, thank you all for your help.

 

[Ampster]

More importantly, is the BMS cutting out? If not that would confirm that the settings of the inverter are now the first line of defense to protect the battery from over charging and that the BMS is providing the final defense.

 

[Freeman656]

BMS is not cutting because the voltages are now in a correct range I guess.
And yes for the 2 lines of defense, with the previous settings I guess the BMS was cutting before the charger, so this gave a strange behaviour...

 

[Freeman656]

Hi again,

I got the error message saying "overcurrent protection" in the Daly BMS which is really strange...
It was charging fine at ~60A, which is fine because the Daly is supposed to go to 75A (and is configured as such in the settings) and the second after, the amps reading went up to 100A for no reason (on the screenshot, it shows 0 because it was for a split second, so the time I take the screenshot the ChgrMOS went off and the amps went to 0).
The multiplus is configured to deliver a maximum of 3500W, which is around 65-70A.
So is it possible that the Daly has wrong amps reading after a certain time ? I'll try to monitor the amp reading with some screen capture tool in the next days to see if the reading seems fine or not.
For the time beeing, I see the MP back to 2500W, which seems fine even with the potentional missreading of the daly.

 

[Berseker]

Any update on this??