Multiplus II loads battery to 57 volt, although 3.45 / 55.2 has been defined

DIY
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1

Multiplus settings: Absorption voltage=55.20 V and Float voltage=53.60 V .

BMS settings: Cell OVP=3.6, Vol. Cell RCV (V)=3.450.

The battery is loaded to (approx) 57Volt and then absorption starts.

I would expect that the Multiplus would never load higher than 55.2 volt and start absorption earlier. Now every day, the battery is loaded over the expected 16 * 3.45V = 55.2 V.

Question:

  • is my expectation that Multiplus would never charger over 55.2 correct?
  • What makes the multiplus decide to stop charging?

Thanks in advance for your response.

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2

Good evening,

Check your charge voltage in the Victron master of your install once more and check in your GC the DVCC settings once more.

Are you sure you have a 16 cell lithium battery, this as many only use 15 cells, normally (Pylontech as example 15 cells) we put on 52V absorption and 51V float.

Then, there are cells which can be charged to 3.55V and others to 3.80V and even 4.00V, meaning, check asap the individual cell voltage, and then go about 10% under it so the BMS will still equalize the cells but your battery will outlasts many more years not to charge it fully every time!

Set it in the master and double check your DVCC in the GX settings once more, that should solve the issue.

What I see is that the battery BMS is still in control over the DVCC and the master inverter.

With the best regards, Jeroen.

3

Depends.
What battery?
Is DVCC on?
Is the BMS set as the battery monitor in the GX system setup and as the controlling BMS in DVCC?

Not a lot to go on here.

4

Jeroen, Nick thanks for answering.

Settings in Multiplus were incorrect, now set as it should (55.2 and 53.6), I will check today whether max voltage is now any better. I will update when results are there.

Do you know a method (API, ModbusTCP, MQTT) to read these values from the multiplus without using the MK3/USB interface?

5

You can pull/push a remote config via vrm and open it in veconfigure.

6

Good morning,

Yep, as Nick describes, and you can also make a graph in VRM with CVL charge voltage limit, CCL charge current limit and DCL discharge current limit.

Regards, Jeroen.

7

Hi Nick, this is an option. How do I pull a multipus configuration through VRM?

8
9

Because I got alarms from BMS, I started searching the values.

I found this graph and through that the related attributes mvc for CVL - Charge Voltage Limit, mdv for DVL - Discharge Voltage Limit, mcc en mdc, which are the operational limits. Also bv=battery voltage and I saw incorrect values. So far so good.

Now I’m looking for the actual Multiplus settings through API/Modbus/MQ, and created separate topic for that.