H1 G2 Investigation into missing BMS Cell Temp (low/high) and Cell Volts (low/high) registers

[FozzieUK]

Initial discussion started in Facebook with Richard W, now transferred to here

Hi Richard, here you go - sorry I did jot down the registers to test I just forgot to send it - i've also added the stop/start which I know works on the H1(G1) the G2 may well be the same as it's sort of a hybrid between the old spec and the new spec - see how you get on.
Check these addresses using the built in modbus read service (Developer Tools, Actions - select Foxess Modbus - Read Registers) selecxt your inverter in the drop down set the register address to read (try holding and input for all of these)
BMS1 MaxTemp 37617 I16 C scale 10
BMS1 MinTemp 37618 I16 C scale 10
BMS1 MaxCellVolts 37619 U16 V scale 10
BMS1 MinCellVolts 37620 U16 V scale 10
BMS1 SOH 37624 U16 % scale 1
BMS1 RemainEnergy 37632 U16 Wh scale 0.1
BMS1 FCC Capacity 37633 U16 Ah scale 10
BMS1 DesignEnergy 37635 U16 Wh scale 0.1
For Inverter Start/Stop
On the H1(G1) if you write to register 41013 with a value of 0 - it will stop the inverter, if you write to 41013 with a value of 1 it will start (after checking) - I know this works on my H1(G1).
The latest spec suggests that you now need to write to 49078 a value of 1 to shutdown the inverter, and if you write to 49077 a value of 1 it will power on the inverter.
(and if you read the value of 49228 it will show 1 if powered on, and 0 if powered off)
You can use the Foxess Modbus - Write Registers service for this.

[FozzieUK]

From Richard

Thanks for these, looks like #37618 does give the lowest cell temp. Results below. There were no differences between input and holding (whatever the difference is?) and what is FCC Capacity?
input / holding
BMS1 MaxTemp 37617 I16 C scale 10 - 241 / 241
BMS1 MinTemp 37618 I16 C scale 10 - 189 / 189 (fox app 2 says 18.8 degrees, close enough 🙂 )
BMS1 MaxCellVolts 37619 U16 V scale 10 - 33 / 33
BMS1 MinCellVolts 37620 U16 V scale 10 - 33 / 33
BMS1 SOH 37624 U16 % scale 1 - 100 / 100
BMS1 RemainEnergy 37632 U16 Wh scale 0.1 - 1152 / 1152
BMS1 FCC Capacity 37633 U16 Ah scale 10 - 478 / 478
BMS1 DesignEnergy 37635 U16 Wh scale 0.1 - 1152 / 1152

[FozzieUK]

I think canton may be away at the moment - so over xmas I will work out what the changes might be, let you edit some of the entity definitions on your system to test them and hopefully we can get you a functional test system.

On the FCC capacity - not entirely sure as the spec doesn't provide detail, I think it might be the maximum charge capacity in Ah the battery is capable of when full (it looks like 47.8Ah for you ) so multiply that by the {maximum cell voltage= 3.6V} * {number of cells in each pack} should equal your individual battery pack Wh capability at full charge. But then equally that might be wrong - with some of these things we just have to track them and work out what they do over time and assess how to deal with them ☺️

The Cell low and high voltage is interesting as on the old specs they used to report in mV whereas now they report step 0.1 i.e. it was 3321 now 3.3V - this is a critical number to the BMS in how it calculates the pack SoC so i'm expecting this might change back in future firmware releases.

[u4h37u]

Thanks for looking into this @FozzieUK

[mechanimal82]

I've now been updated to Manager 1.48, Master 1.31, Slave 1.02 (credit to Fox - it only took 1 email and to wait for the weekend to be over and it was done)

batvolt, and bat_current work as expected now, as do cell MV low/high and temp low/high. And the BMS kWh remaining sensor I mentioned in #702 works now too.

@FozzieUK while I'm here, I checked 37624 and I get "100", which is the same value I now see in the Fox app for SOH

Yep, same for me. I have made the edits as mentioned in #703 and have the SOH showing as a sensor with a value of 100% within the Fox Modbus integration

Here's the output:
values:
"37624": 100

[FozzieUK]

@mechanimal82 Perfect, thank you.

[KNZZZZZZZ]

@FozzieUK
I also did these modifications on my HA Modbus v1.12.2 with the H1-G2 (Manager 1.48, Master 1.30, Slave 1.03).
I can see the new sensors but when I want to enable them I can't do it, it shows the message "Cannot change status. Disabled by Device."
How can I enable it?

Thanks!

[FozzieUK]

I’ve not seen that before with this integration, I think the easiest way to do this is to go to Settings, Devices & Services, click on the ‘>’ on the Foxess Modbus entry, then click on the 3 dots in the right hand corner - click ‘Disable’ say yes to the dialogue… wait for a few seconds and then click ENABLE
Hopefully that will work !

[KNZZZZZZZ]

Now it works indeed!
I suspect it had to do with my old H1-G1 inverter which is disabled in HA and had the same sensors. Thanks!!

[KNZZZZZZZ]

Register 37618 also gives the lowest cell temp on my H1-5.0-G2 inverter.
Is there a simple way to integrate this as a sensor?
Because I am still new to HA.

Thanks!

[FozzieUK]

If you don't mind editing the code on your system (under instruction), then keep an eye on this discussion as I will post some instructions on how to add this to the current build to test it - otherwise you'll have to wait a short while for all the tests to be completed, a request to be put in and a new version of the integration released.

[FozzieUK]

See #735

[FozzieUK]

@u4h37u , @mechanimal82

There is now a beta release v1.13.1b2 that includes these changes - the v1.13.x requires that HA core 2025.x is installed so when you get round to upgrading your ha core - could you please check this release and that everything is reporting as it should (including the SoH sensor).

[mechanimal82]

@u4h37u , @mechanimal82

There is now a beta release v1.13.1b2 that includes these changes - the v1.13.x requires that HA core 2025.x is installed so when you get round to upgrading your ha core - could you please check this release and that everything is reporting as it should (including the SoH sensor).

Have installed B2 and rebooted. All sensors are populated, no errors or unknowns and the SOH, mV values etc are looking correct

[FozzieUK]

perfect, thanks 👍