Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
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.
Screenshot 2025-12-01 at 10.58.49.png
Screenshot 2025-12-01 at 11.22.50.png
I've seen other users complain about this. Did anyone find a workaround? I've submitted a ticket with Fox also.

Cheers.
Re: Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
Update - Fox just unceremoniously closed my ticket on this issue without reply.

I get that it's a complex thing to look into and reply on, but it's a feature of the product nonetheless and it should work correctly. I will keep pressing until I get a satisfactory response.

- Ret
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Re: Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
Are you on the latest firmware? mine used to do this but I'm sure it stopped on one of the recent firmwares.
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Re: Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
Hi Will,

I'm on the following firmware builds:

Inverter (KH-7)

Version_Master:1.52
Version_Slave:1.01
Version_ARM:1.52

Battery (EP11)

Version_BMS:1.009

So, pretty recent I think. I know there are some very recently-released ones above those though.

Thanks,
Ret.
Re: Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
Another update on this...

Fox responded to me and seemed to confirm this isn't "normal". They said they'd upgrade the system and see if that resolves it.

I noticed the BMS upgraded from 1.009 to 1.011 and the Manager firmware on the inverter upgraded from 1.52 to 1.54. Slave & Master firmwares unchanged.

This didn't seem to have any effect. I will give it 24 hours and respond to Fox tomorrow.

@Will - I wonder if you have any historical data you can look back on and see if this was indeed happening on your system, and maybe correlate what caused it to stop? :)
Re: Follow-up: Maintenance Charging/Cycling & Incorrect Energy Accounting
Another follow-up...

Today Fox upgraded my Inverter firmware to:

Version_Master:1.55
Version_Slave:1.01
Version_ARM:1.58

Still no change in the behaviour. This seems like the latest & greatest firmware now too.

- Ret
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