Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
Posted: Mon Dec 01, 2025 4:12 pm
This is kind of a follow-up to my previous post about maintenance charging, but my findings have developed somewhat.
I noticed that while idle (no PV input, no grid charge commanded) the hybrid inverter (Fox ESS KH7) normally cycles between a slow charge of the batteries (to 5% above On-Grid Min SoC) and discharging. Guessing this is probably done for battery health reasons or maybe because of the power topology of the inverter (powered from DC so it's easier/more efficient to just do this rather than run the AC → DC switching at a very low & inefficient level?)
Anyway, this is fine, I don't care that much.
However... annoyingly, the charge power during these cycles is not accounted correctly by the inverter. During the charge part of this cycle, there's no power logged flowing into the battery. This applies to the daily & total energy and instantaneous power Modbus registers. The discharge cycle part registers correctly though.
The consequence of this is that the autarky stats are totally wrong in HA. The battery appears to source more power than it sinks.
This issue creeps into some aspects of the FoxESS Cloud App & Website too. I've attached some examples from the website and also from my own data in Grafana.
I've seen other users complain about this. Did anyone find a workaround? I've submitted a ticket with Fox also.
Cheers.
I noticed that while idle (no PV input, no grid charge commanded) the hybrid inverter (Fox ESS KH7) normally cycles between a slow charge of the batteries (to 5% above On-Grid Min SoC) and discharging. Guessing this is probably done for battery health reasons or maybe because of the power topology of the inverter (powered from DC so it's easier/more efficient to just do this rather than run the AC → DC switching at a very low & inefficient level?)
Anyway, this is fine, I don't care that much.
However... annoyingly, the charge power during these cycles is not accounted correctly by the inverter. During the charge part of this cycle, there's no power logged flowing into the battery. This applies to the daily & total energy and instantaneous power Modbus registers. The discharge cycle part registers correctly though.
The consequence of this is that the autarky stats are totally wrong in HA. The battery appears to source more power than it sinks.
This issue creeps into some aspects of the FoxESS Cloud App & Website too. I've attached some examples from the website and also from my own data in Grafana.
Cheers.