RS485 read China MPPT Solar Controller Charger

This project interfaces with a China MPPT Solar Controller Charger using RS485 communication.

Overview

This charger is user-friendly, but caution is advised with pre-defined profiles like Lifepo4 16S; it's advisable to use user-defined voltages suitable for your battery.

Quick Links

• Alibaba Product Page
• AliExpress Product Page 1
• AliExpress Product Page 2
• AliExpress Product Page 3

Prerequisites

• Python 3.x
• pyserial library

Installation

Install the required Python libraries:

pip install pyserial

RS485 Serial Port Configuration

• Baud rate: 2400
• Check bit: NONE
• Data bit: 8
• Stop bit: 1

Replace /dev/ttyUSB2 in the script with the appropriate serial port for your system. To find the port reboot, plug out and plugin your adapter and enter this command:

dmesg | grep ttyUSB

Connect cables using a RJ12 6P6C terminal adapter. I had success with a FT232-Chip RS485 adapter. See RS485 Connection for details.

• AliExpress Product Page 1
• AliExpress Product Page 2

Query MPPT Charger

Ensure permission for serial port:

sudo chmod 666 /dev/ttyUSB2

Run Python script to query charger:

sudo python3 query-mppt-charger.py to test if your charger is answering

Example Output

root@raspberrypi4:~# python3 /data/query-charger.py
  MPPT Charger Data:
  address: 1
  device_type: 1
  dc_output_status: 0
  excessive_internal_temperature: False
  high_battery_temperature: False
  dc_output_overcurrent: False
  pv_overvoltage: False
  pv_voltage_too_low: False
  charging_voltage_too_high: False
  fast_charging: False
  uniformly_charging: False
  float_charge: False
  max_power_point_tracking: False
  standby: True
  charging_voltage_percentage: 91
  system_charging_voltage_percentage: 0
  battery_type: 4
  system_set_equalization_voltage: 54.7
  system_set_float_voltage: 54.5
  system_set_discharge_limit_voltage: 45.6
  system_charging_current_limit: 60.0
  photovoltaic_input_voltage: 0.0
  charging_voltage: 53.7
  charging_current: 0.0
  charging_power: 0.0
  battery_voltage: 53.7
  dc_output_current: 0.0
  module_temperature: 29
  external_battery_temperature: 25
  total_energy_generated: 75.016

or read with mbpoll:

$ mbpoll /dev/ttyUSB2 -m rtu -b 2400 -P none -d 8 -s 1 -v -a 1 -r 1 -t4:int16 -c20 -1
  debug enabled
  iGetIntList(1)
  Integer found: 1
  iCount=1
  iGetIntList(1)
  Integer found: 1
  iCount=1
  Set function=4
  Set format=int16
  Set number of values=20
  Set device=/dev/ttyUSB0
  mbpoll 1.0-0 - FieldTalk(tm) Modbus(R) Master Simulator
  Copyright (c) 2015-2023 Pascal JEAN, https://github.com/epsilonrt/mbpoll
  This program comes with ABSOLUTELY NO WARRANTY.
  This is free software, and you are welcome to redistribute it
  under certain conditions; type 'mbpoll -w' for details.

  Opening /dev/ttyUSB0 at 2400 bauds (N, 8, 1)
  Set response timeout to 1 sec, 0 us
  Protocol configuration: Modbus RTU
  Slave configuration...: address = [1]
                          start reference = 1, count = 20
  Communication.........: /dev/ttyUSB0,       2400-8N1 
                          t/o 1.00 s, poll rate 1000 ms
  Data type.............: 16-bit register, output (holding) register table

  -- Polling slave 1...
  [01][03][00][00][00][14][45][C5]
  Waiting for a confirmation...
  <01><03><28><00><01><00><01><00><01><02><10><00><45><00><00><00><04><02><3A><02><36><01><02><06><02><1C><00><3E><02><1C><00><00><00><2C><00><00><00><0F>
  [1]:    1
  [2]:    1
  [3]:    1
  [4]:    528
  [5]:    69
  [6]:    0
  [7]:    4
  [8]:    570
  [9]:    566
  [10]:   480
  [11]:   700
  [12]:   1724
  [13]:   540
  [14]:   62
  [15]:   540
  [16]:   0
  [17]:   44
  [18]:   0
  [19]:   15
  [20]:   -23902