VRM values not netting between PV charger and Battery

DIY
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1

Happy Sunday,

I now installed an MPPT within my system and don’t get the VRM to behave as it should (in my opinion).

Current setup:

  • 3 MP2
  • Distributor leading to LiFePo4-batteries
  • External PV inverter at AC-out of MP2s
  • SmartSolar MPPT now simply attached to the distributor
  • Cerbo GX governing all

The VRM display now looks like the following:

vrm
vrm862×653 70.8 KB

The issue I am having is that the power in the battery does not show the battery charge/discharge power, but the total DC output/input to the MP2. If you compare the values in the screenshot, the PV inverter delivers 8.6kW, the MPPT 3.2KW, and the batteries are discharging at 0.5kW. If the batteries are full and the overall load low, then the batteries show “discharging” just because the PV charger delivers the power into the grid (and not the batteries).

How can I get this fixed so that the battery shows indeed only the battery component and not the full DC gross value?

Thank you!
Juergen

2

Hi Jürgen,

I am assuming the batteries are “managed” and are linked through CAN/ BMS? Then make sure that the correct BMS is chosen (not “Multiplus” but whatever BMS you are using).

Johannes

image
image1916×511 78.5 KB

3

Hmmm … that might be the issue. At the moment I do not use/access a dedicated BMS of the batteries, rather only go via the MP2. Need to look into this …
Thank you!
Juergen

4

Seems that it won’t be straight forward to connect the BMS of the batteries with the Cerbo - there seem to be some incompatibilities of the Taico batteries with Cerbo.

In that case,

  1. is there any other chance to get this netting to work?
  2. could the Lynx Shunts be a solution?

Best, Juergen

5

Good Morning Jürgen,

you could work with a shunt: SmartShunt | Victron Energy
But: SOC will always only be a best guess.

J.

1 Like
6

Thank you!