DC Power Always Negative – But Flow Arrow Wrong (Points into Battery even During Heavy Discharge)

[JuicyMango (Johannes Stuschka)]

Hello Victron community,

I’m having a persistent issue with my Victron system and hope someone has encountered this before.

No matter whether I’m connected to shore power or running off-grid , and even when the battery is fully charged (100%) , the DC power reading always shows a negative value (e.g. -250W) when the DC system is under load.

The real problem is the direction of the flow arrow :

• When loads are running (like lights, pumps, or other consumers), the system shows negative DC power, which makes sense since energy is being used.

• But the flow arrow always points from the DC system into the battery – as if energy is charging the battery.

• Even during boat travel with high DC usage, the diagram shows negative power (correct), but still flow into the battery (wrong).

So in short:

→ The numeric DC power reading is correct ,

→ but the flow direction is always wrong and shows charging, even during clear discharge.

The generator is off, shore power on or off doesn’t affect this behavior.

Could this be a bug in the GUI, a measurement issue, or something wrong in the shunt or system config?

I’ve attached screenshots showing the issue clearly.

Thanks for any advice or ideas!

Best regards,

Johannes

[pwfarnell]

Negative DC power is the battery being charged, positive DC power is power being used. The values and arrows are correct. Do you have a shunt measuring your DC system or do you just have the “Has DC system” enabled.

If you have a DC system shunt it is installed backwards.

If you do not have the DC system shunt then the DC is a calc using all other data and any errors in any of the information end up in the DC box. There is a good explanation in this FAQ. You only need a 2% error in one of your current readings to give 200W eror in the DC tile.

The DC System Power on a Venus device is jumping, erratic or does not match other loads

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[JuicyMango (Johannes Stuschka)]

Thank you very much for your reply!

Victron manuals tell that if your are using „lynx smart bms ng“ you don’t need an extra shunt.

Also did a software downgrade later that day and upgraded again to the latest version. But it didn’t change anything.

I then changed the UI to the new version - and it is working. I don’t know how the UI -old and - new affect the calculations but it is working.

[pwfarnell]

I have NG batteries and Lynx NG and my system shows OK on the new UI. You do not need a SmartShunt to measure the batteries as the Lynx BMS does this. I have added a SmartShunt as a “DC Energy Meter” type “DC System” to measure my DC system that is not measured by the MPPT or Inverter or alternator so I always get an accurate value in the DC box and DVCC can allow for the DC loads when the GX is setting charger currents if these are limited for an particular reason.