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H3 Hybrid - automation via evcc - battery via grid just 400W

Posted: Sun Oct 05, 2025 8:04 am
by McKeolegh
Good Morning,

I have a little "problem" with my Fox ESS H3 hybrid inverter, my ECS2900-2 and my automation via evcc (version 0.208.1).

With evcc I can set up a plan to charge my battery from the grid. I use a dynamic pricing so it would be nice to charge my battery when it's cheap when there is not enough sunlight / there will be not enough sunlight - winter is coming! ;)

In the Fox ESS App I can turn on charging from the grid and it works. The battery will be charged with ~7.9 kW.
In my evcc App I can turn on charging from the grid but it will just charge the battery with 400W.
I would prefer the evcc app because it's easier to configure and faster.

The evcc app runs on a little raspberry pi and gets the data using a RS485 -> WLAN adapter (modbus). I can see all my data from the inverter, I can see the SOC, I can charge my EV without using the battery or just with electricity from my PV. So far I am very happy with it - but the "battery-grid-charging-problem" still annoys me.

I've asked the evcc community before - no solutions found. Everything should be configured correctly.

Thanks for your help.

Sunny greetings from Germany
McKeolegh

Re: H3 Hybrid - automation via evcc - battery via grid just 400W

Posted: Sun Oct 05, 2025 11:10 am
by Dave Foster
Sorry I don’t know much about the evcc app but if it’s only charging at 400 watts that sounds like it isn’t setting a charge period or a schedule, instead it is simply lifting the minSoC setting which forces the batteries to maintenance charge.

The maintenance charge is 5A at your battery volts which will be ~90 volts for ECS2900-2 which is the low level charge you are seeing.

There is no way to change the maintenance charge power, so you need to find out why it is lifting minSoC and not setting a charge period or using the modbus to force charge using the remote control active power register - when using that you write the charge power to the active power register so might be worth seeing if there are any settings to control power or current (or the method it uses) to charge.

Re: H3 Hybrid - automation via evcc - battery via grid just 400W

Posted: Sun Oct 05, 2025 11:31 am
by McKeolegh
Thank you Dave!
Now I have a clue where to look or what to ask for at the evcc community.