python-pylontech

Python lib to talk to pylontech lithium batteries (US2000, US3000, ...) using RS485

What is this lib ?

This lib is meant to talk to Pylontech batteries using RS485. Sadly the protocol over RS485 is not some fancy thing like MODBUS but their own crappy protocol.

How to use this lib ?

First of all, you need a USB to RS485 converter. They are many available online for some bucks.

Then, you simply need to import the lib and start asking values:

>>> import pylontech
>>> p = pylontech.Pylontech()
>>> print(p.get_values())
Container:
    NumberOfModules = 3
    Module = ListContainer:
        Container:
            NumberOfCells = 15
            CellVoltages = ListContainer:
                3.306
                3.307
                3.305
                3.305
                3.306
                3.305
                3.304
                3.305
                3.306
                3.306
                3.307
                3.307
                3.308
                3.307
                3.306
            NumberOfTemperatures = 5
            AverageBMSTemperature = 29.81
            GroupedCellsTemperatures = ListContainer:
                29.61
                29.61
                29.61
                29.61
            Current = -3.5
            Voltage = 49.59
            Power = -173.565
            RemainingCapacity = 39.5
            TotalCapacity = 50.0
            CycleNumber = 5
    -->8-- SNIP -->8--
    TotalPower = -525.8022
    StateOfCharge = 0.79

>>> print(p.get_system_parameters())
Container: 
    CellHighVoltageLimit = 3.7
    CellLowVoltageLimit = 3.05
    CellUnderVoltageLimit = 2.9
    ChargeHighTemperatureLimit = 33.41
    ChargeLowTemperatureLimit = 26.21
    ChargeCurrentLimit = 10.2
    ModuleHighVoltageLimit = 54.0
    ModuleLowVoltageLimit = 46.0
    ModuleUnderVoltageLimit = 44.5
    DischargeHighTemperatureLimit = 33.41
    DischargeLowTemperatureLimit = 26.21
    DischargeCurrentLimit = -10.0

Dependencies

python-pylontech needs python 3.5 or greater (but please, use at least 3.7 or more if possible to be future-proof).

This lib depends on pyserial and the awesome construct lib.

Hardware wiring

The pylontech modules talk using the RS485 line protocol.

Pylontech side

The first DIP switch on the pylontech indicates the line speed. It must be off (0, down position) so that the speed is set to 115200 Bd.

The RS485 port is exposed on the pins 7 & 8 on the RJ45 connector names RS485.

Client side

Any RS485 to USB (TCP/IP not yet supported) converter should would. You just have to wire the two pins above to the A and B ports (swap them around if it doesn't work). of your converter.

I personally use cheap chinese "RS485 to USB" converters worth a couple of bucks each.

Known bugs

Mixing between US2000 and US3000

If you are using US2000 and US3000 batteries, then the main battery must be a US2000. Please see bug Frankkkkk#2 (comment) for more information

skoky/python-pylontech