question

andr avatar image
andr asked

PV inverter assistant reducing power to zero. Multiplus reading not pylontech BMS values?

System: multiplus 2 5000 48v 50/70

6* pylontech 2000c

Victron Venus GX

sma sunny boy



The system has worked correctly for one year..the batteries can be charged up to 53.2v and are fully balanced.


It seems that the PV inverter assistant uses the volt and current values of the internal multiplus battery Monitor and reduces the power by frequency shifting to zero. If you disconnect the Venus GX device, exactly the same happens as with the utp cable.

In the GX device the pylontech BMS is selected as battery monitor.

Firmware updates and downgrades to the previously working versions in both the GX (2,92) and the multiplus (281) have no effect.

Double checked configured frequences for the sma (51hz, 52hz,53hz) all correct like in the sma configuration it's self.


The pb inverter assistant always goes up to 51,7 or higher when the pylontech are for example at 71% soc and the multi internal battery monitor shows 85 soc or higher. For the internal this might be correct but I think the pylontech BMS Monitor should be used but seems that it is not used for the shifting.


The question for me is: why does the multiplus no longer seem to get knowledge of the correct volt and currents of the pylontech BMS via the Venus GX? The correct values are needed to adapt the frequency correctly.


Victron Connect, the remote console shows all pylontech values correctly.


I am now at a loss for ideas, except that the Venus GX may have a defect in the transmission to the multi. Cables have all been replaced and a and b versions of the Victron BMS cable have been tested.

Any ideas?


Thx, kind regards

André

BMV Battery MonitorLithium BatteryPylontech
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3 Answers
solarmax-canarias avatar image
solarmax-canarias answered ·

Reinstall the GX Software and also check if in the pylontech parameters al batteries appear to be “Online”.

Do you have DVCC activated?

Also look for those values once the system is slowing down charge: pylontech -> parameters -> CCL value, how high is it?

It’s the power the BMS wants from the charger/ solar generator



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andr avatar image andr commented ·
Hola @Solarmax Canarias ,


Thanks for responding. All batteries are online , dvcc is forced on, CCL is at its max. All parameters are very well, except the voltage of the battery monitor in the multiplus. See my other answer to guy.


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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Andr,

Do you have a multimeter and training in how to use it safely?

If not, I would recommend contacting a technician to help with further troubleshooting.

If you do, I would start with a fundamental diagnosis of the system wiring.

Measure and record battery voltage readings at the battery terminals (or as close as possible on the connection point to the DC bus as pylontech use a protective plug without direct terminal access when connected).

Measure and record battery voltage readings at the battery connection lug points point of the MultiPlus itself (not where it connects to the bus).

What are these values, and how do they compare with the values reported in the GX device for the MultiPlus (in the device menu) and the Battery BMS.

If there is any variation in these values, there is likely a wiring issue somewhere, a bad connection, or partially blown fuse that is adding resistance to the DC side of the wiring system.

If all these values are equal, let me know what they are and we can proceed with another troubleshooting step.

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andr avatar image
andr answered ·

Hi @Guy Stewart (Victron Community Manager) ,


Thanks for your fast reply. I measured everything, hopefully at the correct places. I took some pictures, too.


Fyi:

The PV inverter assistant is currently not added we have bad weather conditions, so I need every watt I can get. Ig it is installed the frequency will go up to 51,8hz after some seconds.


The SOC is 89% in both monitors (BMS and multiplus)


  • Battery voltage at the pylontech DC bus: 50,2v
  • Battery terminal multiplus: 50,2 volt
  • Battery lug points: 50,2 volt
  • GX device shows: 50,3 volts


I attached pictures of all measurements.

Thanks , best regards


André



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