jesus-99 avatar image
jesus-99 asked

Question about charge current limit

Hello everyone, thank you for reading this post first of all. Let me tell you about my installation:

  • Three 10000 VA Quattro configured as a three-phase system.
  • One pylontech US3000C battery with 48 V and 37 A of charge (I am planning to buy more in the future but for now, I am testing the system with only one).
  • Fronius Symo 3.7 kW inverter.
  • Raspberry pi zero 2w with Venus 2.90 installed.

Basically, I have an off-grid system, in which the Fronius collects energy from the solar panels and sends it to the Quattro to charge the battery (I am testing the system without any load, all the energy should go to the batteries). The fronius is connected to the Quattro through AC out.

The problem I have is with the battery charging current limitation. On the one hand, in the Quattro configuration using the Ve.Bus system configurator software, I assign a maximum charging current of 9 A to each one (in total, they will charge the battery with 9*3 = 27 A, below the maximum for greater safety). On the other hand, in the Venus device, I have the DVCC enabled and I limit the current to 30 A. In addition to that, I have the Quattros loaded with PV support assistant. However, despite all these limitations, when I start the system, the batteries are charged with 39 A and 50 V, exceeding the imposed limitations. The Fronius only provides power for a few moments and then shuts down. Then it turns back on (and charges at 39 A) again for a few moments and shuts down again.

If anyone knows why the current limitation is not being met, I would greatly appreciate it.

Best regards.

MultiPlus Quattro Inverter Chargerbattery chargingVenus OSPylontechRaspberry Pi
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

1 Answer
marcve avatar image
marcve answered ·

I would have a look if your Fronius really throttles down. I noticed with my Solis ( connected to AC-Out ), when not configured correctly, it pushes the charging voltage and current over the limit, and the bms shuts the batteries down. One thing I noticed with my Quattro II, when I set the voltage in the assistant to the correct value, the Lifepo cells were charged to high. I had to adjust the total of the cells voltage 0.4 volts below the calculated value in the assistent, to have the cell voltage charge handled correctly by the Quattro.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.