Write configuration to BMS

[waltertheodor]

System description:

4 x Victron smartSolar MPPT 150/100 with 30kWp solar panels
3 x Victron Multiplus II 48/5000
4 x battery 48V/(16 x EVE LF280K 280Ah)
	BMS-A V11.26 V11.XW JK-B2A24S20P
	BMS-B V11.26 V11.XW JK-B2A24S20P
	BMS-C V10.09 V10.XW JK-B2A24S20P
	BMS-D V10.09 V10.XW JK-B2A24S20P
	BMS-X V11.261 V11.XW JK-B2A24S20P (test system)
	
Venus-OS-Large v3.32 on Raspberrypi 4, 4GB RAM 
	Dbus-Serial-Battery 1.2.20240401 via RS485/USB
	Battery-Aggregator v3.0.66

I would like to configure my BMS via Node-Red and the "Custom-Control" node. In particular, I want to reset the SOC to 100% and use the "ForceChargingOff" and "ForceDischargingOff" functions. Unfortunately, this is currently only possible via Bluetooth and the app. Is there a solution to do this via the serial interface?

Walter

[mr-manuel]

No

[waltertheodor]

That is a clear statement. But is there a way to build such a solution into Dbus-Serial-Battery? There seem to be quite a few JK-BMS users who would like to have a solution for the SOC reset problem.

[mr-manuel]

If you search in the discussions and issues you find a lot of informations. It's simply not possible because JKBMS decided that via serial connection you cannot change anything. There are many other solutions to the SOC reset problem, all well described in many issues and discussions as well as in the config.default.ini.

I will add a section to the FAQ, since this is a most common question.

solution 1

dbus-serialbattery/etc/dbus-serialbattery/config.default.ini

Lines 28 to 57 in 59a6d00

	; --------- SOC reset voltage ---------
	; Description:
	; May be needed to reset the SoC to 100% once in a while for some BMS, because of SoC drift.
	; Specify the cell voltage where the SoC should be reset to 100% by the BMS.
	; - JKBMS: SoC is reset to 100% if one cell reaches OVP (over voltage protection) voltage
	; As you have to adopt this value to your system, I reccomend to start with
	; OVP voltage - 0.030 (see Example).
	; - Try to increase (add) by 0.005 in steps, if the system does not switch to float mode, even if
	; the target voltage SOC_RESET_VOLTAGE * CELL_COUNT is reached.
	; - Try to decrease (lower) by 0.005 in steps, if the system hits the OVP too fast, before all
	; cells could be balanced and the system goes into protection mode multiple times.
	; Example:
	; If OVP is 3.650, then start with 3.620 and increase/decrease by 0.005
	; Note:
	; The value has to be higher as the MAX_CELL_VOLTAGE
	; You also have to set CELL_VOLTAGES_WHILE_CHARGING accordingly, if you set CCCM_CV_ENABLE to true
	; else the charging current will be reduced to 0 before the target voltage is reached and the
	; battery will never switch to float
	SOC_RESET_VOLTAGE = 3.650
	; Specify after how many days the soc reset voltage should be reached again
	; The timer is reset when the soc reset voltage is reached
	; Leave empty if you don't want to use this
	; Example:
	; Value is set to 15
	; day 1: soc reset reached once
	; day 16: soc reset reached twice
	; day 31: soc reset not reached since it's very cloudy
	; day 34: soc reset reached since the sun came out
	; day 49: soc reset reached again, since last time it took 3 days to reach soc reset voltage
	SOC_RESET_AFTER_DAYS =

solution 2

dbus-serialbattery/etc/dbus-serialbattery/config.default.ini

Lines 171 to 192 in 59a6d00

	; --------- SOC calculation ---------
	; Description:
	; Calculate the SOC in the driver. Do not use the SOC reported by the BMS
	; SOC_CALCULATION:
	; True: Calc SOC in the driver, do not use SOC reported from BMS
	; - The SOC is calculated by integration of the current reported by the BMS
	; - The current reported from the BMS can be corrected by
	; the map (SOC_CALC_CURRENT_REPORTED_BY_BMS, SOC_CALC_CURRENT_MEASURED_BY_USER)
	; - The SOC is set to 100% if the following conditions apply for at least SOC_RESET_TIME seconds:
	; * Current is lower than SOC_RESET_CURRENT amps
	; * Sum of cell voltages >= self.max_battery_voltage - VOLTAGE_DROP
	; - The calculated SOC is stored in dbus to persist a driver restart
	; False: Use SOC reported from BMS (none of the other parameters apply)
	; More info: https://github.com/Louisvdw/dbus-serialbattery/pull/868
	SOC_CALCULATION = False
	SOC_RESET_CURRENT = 7
	SOC_RESET_TIME = 60
	SOC_CALC_CURRENT_REPORTED_BY_BMS = -300, 300
	SOC_CALC_CURRENT_MEASURED_BY_USER = -300, 300
	; Example to set small currents to zero
	; SOC_CALC_CURRENT_REPORTED_BY_BMS = -300, -0.5, 0.5, 300
	; SOC_CALC_CURRENT_MEASURED_BY_USER = -300, 0, 0, 300

[mr-manuel]

How can I reset the SOC to 100%

[waltertheodor]

Many thanks for the tips. I know them and they work very well with my installation.
But why does JKBMS say that it is not possible to write values via the serial interface?
This is not true, at least for my test system (BMS-X, see first post...).
For example, I can switch charging and discharging on and off with these command sequences:
Charge On: 4E 57 00 13 00 00 00 00 02 03 00 AB 01 00 00 00 68 00 00 01 D1 Response: 4E 57 00 13 00 00 00 00 02 00 01 AB 00 00 00 00 68 00 00 01 CE
Discharge On: 4E 57 00 13 00 00 00 00 02 03 00 AC 01 00 00 00 68 00 00 01 D2 Response: 4E 57 00 13 00 00 00 00 02 00 01 AC 00 00 00 00 68 00 00 01 CF
Charge Off: 4E 57 00 13 00 00 00 00 02 03 00 AB 00 00 00 00 68 00 00 01 D0 Response: 4E 57 00 13 00 00 00 00 02 03 00 AB 00 00 00 00 68 00 00 01 D0
Discharge Off: 4E 57 00 13 00 00 00 00 02 03 00 AC 00 00 00 00 68 00 00 01 D1 Response: 4E 57 00 13 00 00 00 00 02 00 01 AC 00 00 00 00 68 00 00 01 CF

[mr-manuel]

This is the info the developers gave me. Only with the new inverter BMS it seems to be possible.

If it works for you feel free to open a PR. Best in my repository. Evaluate also the response, since there are many BMS where this won't work for sure.

[waltertheodor]

It would be enough for me if the two functions "Charge ON/OFF" and "Discharge ON/OFF" were implemented in such a way that they could be used via the Victron node "CustomControl".
For my tests I use a JK-B2A24S20P, software: V11.261, hardware: V11.XW. The command sequences work with this. I will still test whether it works with my older JK-B2A24S20P (V10.09 V10.XW).
First of all, many thanks for your offer.

[EdKok]

@waltertheodor Did you book any progress on this?
I'm also looking for a possibility for switching (Dis)Charge, preferably with Node-Red.