Constant Battery discharge on 100% SoC

[dripphone]

Hello,
I notice that there is a quite constant value for battery discharge (from modbus) when the SoC reaches 100%, while there is enough sun (feed-in). Can anyone explain?
Although the SoC does not reduce, I still wonder where this discharge comes from.
It's around 160-190 W.

[dripphone]

Does anyone else notice the same behaviour?

[joeylien]

Hi there,

yes, I have the same behavior. I think it might actually be beneficial to overcome battery inertia wenn high loads suddenly activate in the house?

For that reason, some of my friends configured their batteries (non-Fox) to do exactly that.

Cheers!

[WyndStryke]

Probably the power needed to run the BMS and inverter. Although on mine, the sensor shows much less, more like 15W. Note that on 3-phase systems the inverter will most likely need to consume 3x more power to stay active than on a single-phase system.

Regarding feed-in, on my system (KH7 with EC4300-H4 battery and 1.37 manager firmware) when there is a) abundant solar, and b) the SoC is under 97%, despite the sensors displaying zero battery charge power, the SoC rises by about 1% every 5 hours or so. This seems to correspond with a very slow 60W charge on my system. It's steady and very consistent, to the point that I can predict the SoC rise via an integral helper on invbatpower which adds 60W charge during the feed-in mode.

I also suspect that the sensors show slightly different behaviour depending on the firmware version (for example, the inverter self-consumption might be shown as house load instead).

[dripphone]

Also what I noticed (I assume somehow related) is that the energy counter of the battery cannot be true (Battery Charge/Discharge Total (FoxModbus)).

According to this, my Battery produced more energy during last month than it consumed (charged)

[rappelkiste]

Hi,
did you solve this issue in any way...
I'm having my H3-12 connected via Modbus to my HomeAssistant-Server and I currently get Battery charge 966 to discharge 2049 kWh...
And I also see about 220W discharge while the battery is at 100% soc.

Thanks

[dripphone]

Unfortunately not. Same behavior, even I updated to the latest firmware couple of weeks ago.
Today for example, I see that the discharge started straight with 400W once the SoC reached 100%, and is slowly decreasing to 160-190W permanent discharging.

[Will]

BMS is powered from the battery and it's normal for the battery to bleed off power when fully charged and cycles between 100% and 95% then charges back to 100% again, repeating. This is by design to protect the battery.
If you have no solar input the battery will slowly drain overtime as the BMS is powered off the battery, only during charging is the BMS, then powered from the inverter.

[dripphone]

I don't get it.
During normal sunny days, my SoC once charged, stays on 100% until evening.
I don't see any cycling like 100-95-100.

But even if the BMS requires that energy, wouldn't it make more sense to "ignore" or consider this amount of energy somehow differently, rather than counting it as normal discharge?
This makes the battery statistics and evaluation quite inconsistent in my eyes.

[Will]

Different hardware models and firmware behave differently. The system losses for operation are not counted anywhere as such but will appear in the difference between your charge and discharge totals.

[rappelkiste]

But how does for example the app determine the used energy from battery when you can not exactly say how much has been discharged for real use?