YamBMS ( Yet another multi-BMS Merging Solution )

Tip

If compiling the source code is too difficult for you, I can provide you a custom firmware that is easy to install from a web page. You can contact me privately on the DIY solar forum.

ESPHome application to monitor BMS and communicate with inverters supporting CAN bus protocol compatible with Pylontech, GoodWe, SMA, Victron or Luxpower (EG4).

Note: Pylontech uses 15S/48V and many others uses 16S/51.2V ! Other battery profiles that utilise the PYLON protocol with different cell counts may also work, e.g. Alpha Ess Smile, BYD Battery-Box LV Flex Lite. Select the correct battery profile in the inverter to match your battery pack ! The ESP32 communicates with the BMS using the BLE / UART / RS485 protocol and then sends the CAN bus frames to the inverter via the CAN bus transceiver.

Sends over CAN bus to inverter:

• Battery Voltage
• Battery Current (+charge, -discharge)
• State of Charge (SoC) SoC 100% will be sent to your inverter only when the battery is fully charged
• State of Health (SoH)
• Max cell V. and ID
• Min cell V. and ID
• BMS temperature
• Charging voltage
• Charging max amps
• Discharge min voltage
• Discharge max amps
• Battery name
• Alarms: Cell over/under voltage, Charge/discharge over current, High/low Temp, BMS fault

Note: this code support multi-BMS and multi-shunt connection per inverter with a single ESP32 and should work with inverters that support the CAN bus protocol PYLON, SMA, Victron or LuxPower (EG4). I'm only testing it with my Deye SUN-6K-SG03-LP1-EU inverter.

This project is still in development and testing...

Dedicated topic on DIY Solar Forum

YamBMS

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Contents

1. Supported devices
2. YamBMS behavior
3. YamBMS functions
4. Charging logic
5. CAN bus protocol
6. Schematic and setup instructions
7. How to create your YamBMS YAML
8. Installation procedure
9. Troubleshooting

Try YamBMS with the DEMO firmware

You can simply test the application with a generic ESP32 without compiling and connecting anything on your ESP32. The DEMO firmware is composed of 3x BMS and 1x Shunt (fake) for a 48V LFP system.

Important

YamBMS_DEMO_ESP32.factory.bin is intended for a generic ESP32, does not work with ESP32-S3. If you want to test YamBMS DEMO with another board you need to compile the firmware with the multi-bms_DEMO.yaml.

1. Download YamBMS_DEMO_ESP32.factory.bin
2. Follow the procedure explained in this document.

If you want to add a CAN transceiver on this DEMO board here are the GPIOs to connect it to :

tx_pin: 23 # to CAN board CTX
rx_pin: 22 # to CAN board CRX (with 4.7K resistor except for SN65HVD230)

Requirements

• ESPHome 2024.6.0 or higher
• ESP32 MCU
• CAN Transceiver (only with TJA1050/TJA1051 : 4.7K resistor for 5V to 3V3 level shifing)
• BMS JK-B*, JK-PB* (other BMS brands already integrated with ESPhome can be added easily)
• Inverters supporting CAN PYLON/Goodwe/SMA/Victron Low Voltage protocol
• Optional: 48V to 5V DC-DC converter to power the ESP32 from the JK-BMS VBAT pin (URB4805YMD-10WR3 or VRB4805S-6WR3)
• Optional: JK RS485 adaptor and RS485 to TTL 3V3 adaptor (see schematic section)

Changelog

• YamBMS 1.5.1 :
  • The conditions for combining BMS and the charging and discharging instructions no longer have any relation with the errors_bitmask sensor, the new system relies on the three binary_sensor online status, charging allowed and discharging allowed being linked to the status of alarms and switches.
  • The BMS combination procedure has been completely rewritten.
  • Improved structure and ID names of bms.yaml.
  • The yambms.yaml and yambms_combine.yaml global variable names have been changed for better code reading.
  • Improved code regarding the CAN bus esp_light status for boards without integrated LED.
  • New Atom S3R board and Smartshunt BLE shunt.
  • New JBD, Seplos V1 V2, JK-B RS485 (display port) and FAKE BMS.
  • New YamBMS DEMO YAML and firmware offered to test and discover how YamBMS works.
  • New management of temperature sensors (no longer limited to two sensors).
  • @Der_Hannes fixed the AtomS3 black screen issue (with esphome > 2024.7.3) and developed new code for display management based on the ili9xxx platform.
  • Auto CCL/DCL functions have been fixed to work with JK-PB and new JK-B BMS, see this issue.
  • The UVPR and OVPR sensors are no longer used and replaced by UVP and OVP to ensure operation with all BMS.
  • @txubelaxu fixed a bug in the JK-PB RS485 component that could cause a false battery voltage value to be sent, see this issue.
  • Improved documentation, added a HowTo to create its main YAML, warning about galvanic isolation.
• CANBUS 2.3.7 : If there is no response from the inverter, the time before a new communication test has been reduced from 120s to 60s, added Victron 0x372 nbr. of modules blocking charge/discharge.
• YamBMS 1.4.5 : Changed the way to configure WiFi/Ethernet network, added ESP32-C3 ETH01-EVO ethernet board, reduction of the number of YAML bms files, UART rx_buffer_size is set to 512 by default for JK-B and JK-PB, new JK-BMS BLE sensors (last commits of @syssi) and new BLE standard version
• CANBUS 2.3.6 : Sending CAN frames stops immediately if there are no combined BMS
• YamBMS 1.4.4 : Multi-shunt support, Simplified and new YamBMS option battery chemistry, slider min/max values ​​are automatically configured based on the battery chemistry and cell count, added YamBMS Fallback Hotspot, added YamBMS Update service, added PVbrain2 and Atom Matrix board, added PSRAM settings YAML (not enabled by default), new MIN/MAX temperature sensor, added DC current icon, fixed dual sensor Cell UVPR (MAX) bug, Improved combine code, Breaking change : Atom S3 GPIOs 1 and 2 reversed
• CANBUS 2.3.5 : New MIN/MAX temperature / sensor ID, Improved Victron protocol (online/offline battery modules, installed/available battery capacity)
• CANBUS 2.3.4 : Fixed bug of canbus link validation without inverter connected
• YamBMS 1.4.3 : Added Victron and Junctek KH-F Shunt support and Requested Force Charge function based on SoC start/stop, new Total Daily Energy sensors
• CANBUS 2.3.3 : Added Automatic BMS name selection and Requested Force Charge Bit 3/4/5 (PYLON 0x35C)
• CANBUS 2.3.2 : Added LuxPower protocol with updated can_id 0x355, 0x356, 0x359 and 0x35C
• CANBUS 2.3.1 : Improved the procedure for sending canbus frames with reduced loop time, rewritten of the canbus link validation code and added Inverter Heartbeat Monitoring function
• YamBMS 1.4.2 : Added new Auto CVL Boost V. and Rebulk SoC functions, new debug.yaml for ESP32 and ESP32-S3, improved code and comments
• YamBMS 1.4.1 : Rewriting of the alarm system, bug fixes and improvement of the charging logic (new status Cut-Off), icon allocation for each sensor, UART and CANBUS !extend ${vars}, New sensor YamBMS Delta Cell V., Improved Battery SOC logic
• YamBMS 1.3.2 : New var yambms_cell_count, the BMS charge or discharge switches can be activated separately without causing the decombination of the BMS, new minimal version of the BMS YAML in order to reduce the loop time
• YamBMS 1.3.1 : First multi-BMS version named YamBMS

References

• Thanks to @syssi for help and making many BMS components (JK, JBD, Seplos, Pace, etc.)
• Thanks to @txubelaxu for help and making the JK-PB RS485 component.
• Thanks to @uksa007 for making the original CANBUS code.