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hemiman avatar image
hemiman asked

Cerbo GX multiple charger controller summation error

20220322-1058401.jpg144 + 698 = 842w

20220322-1058351.jpgPage View = 813w

I've noticed a difference in the reporting between the "Menu" view and "Page" view in my Cerbo GX with CTX-50 connected to two Victron Charge controllers. Not sure why they are different. The total doesn't add up two the individual values reported in the menu. It's accurate at the low wattage values, but the error grows as the watts increases to about 29w off. I realize that the values can move around, but I can switch back and forth and see the same reported data. Anyone else see this? Software bug?

cerbo gx
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20220322-1058401.jpg (1.9 MiB)
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2 Answers
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pwfarnell answered ·

Is it voltage drop which increases at higher power if the device list value is calculated at the MPPT voltage and the overview screen is at the shunt voltage. You have about 60A so 29W is a 0.5V loss over cables. Just a thought. See if you can read the MPPT outlet voltage somewhere.

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hemiman answered ·

Hmmm....The output power of each MPPT matches (via blutooth) what is displayed in the "menu" window with each individual MPPT broken out. Not all power from your solar flows into my shunt. Power into the shunt would be (Total Solar Input watts - Load watts - line loss) = Remaining Power into your shunt. But I guess the Cerbo GX could be somehow counting some loss?

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