Puzzled with Victron report battery SoC.

[Skyliner33]

I have a Roamer battery. I'm getting quite a disparity from the Readings about state of charge.

Cerbo showing 99%



SmartShunt (or not so smart :/) shows 51% (current draw -1.24A)


Victron mains battery charger showing Absorption charge with 0.0A in.




Any suggestions whats going on?

 

[Sim60]

On your Cerbo, go to settings and select device list. Post a screenshot.
Is it the Shunt that's providing the SoC reading on the Cerbo, or are reading it directly from the Roamer battery?
Look at previous posts where the battery BMS gets out of sync with the Shunt as it doesn't track low level charge/discharge.

Simon

 

[roadtripper]

If those readings are all taken at the same time then the disparity that catches my eye is not the SoC (which is always an estimate and can differ based on how it's derived) it's the voltage.

The BMS, Shunt and Charger should all be seeing the voltage as they should always be closely connected to the same battery - a minor difference is to be expected but those are quite large differences.

How are they wired?

 

[Dellmassive]

Disconnect your loads from the battery then do a zero current calibration on the victron shunt.

That should bring me 0 amp reading in a line with the Roma battery internal BMS Reading.

You need to do it by disconnecting the loads apart from the shunt or use a current clamp to verify the actual Reading and set as per the current clamp.

 

[Dellmassive]

Pulling fuses would be the easiest way to disconnect your loads.