ESPHome MitM Deye

Man-in-the-middle adapter intercepting CAN bus messages between Deye BMS and inverter for enhanced control.

Based on Adminius/mitpylon.

Disclaimer

USE AT YOUR OWN RISK. This modifies critical battery management communication. No liability for damage to equipment or property.

Overview

The Deye BMS protocol has a fixed charge voltage (58.4V). This adapter sits on the CAN bus between BMS and inverter, modifying frames to enable dynamic control.

Variants

Two YAML configs are provided:

File	Use case	SOC sources
mitmdeye.yaml	JK BMS + Deye packs	JK BMS, Pack 1, Pack 2
deye_only.yaml	Deye packs only (no JK BMS)	Pack 1, Pack 2, ... (N packs)

Capabilities

• Dynamic charge voltage override via adjustable offset
• Charge/discharge current limiting without RS485
• Multi-pack SOC averaging with 2% delta filtering and 1% minimum protection
• Force charge, discharge protection, charge scheduling
• Full Home Assistant integration (monitoring + control)

Hardware

Required

• ESP32-C6 (dual internal CAN controllers)
• 2x CAN transceivers:
  • 5V: TJA1050 with 4.7k resistor on RX
  • 3.3V: SN65HVD230 (VP230)

Alternative

• Any ESP32 + MCP2515 CAN controller + 1x transceiver

Tested

• Deye SE-G5.1 Pro BMS
• Deye SUN8K / SUN12K inverters
• ESP32-C6

CAN Frames Modified

Frame	Purpose	Modification
0x351	Charge voltage & current limits	Voltage offset, current limiting
0x355	State of Charge (SOC)	Multi-pack averaging, 1% protection hack
0x35C	Charge control flags	Force charge, enable/disable
0x371	Charge current override	Dynamic current control

All other frames pass through transparently.

Connection Diagram

Home Assistant Integration

Sensors (JK BMS variant): battery voltage, current, temperature, power, SOC (JK BMS, Pack 1, Pack 2, Combined), charge/discharge limits, BMS/inverter connection status

Sensors (Deye-only variant): per-pack voltage, current, SOC, SOH for each pack (e.g. Pack 1 Voltage, Pack 2 SOC), plus combined battery V/I/T/P/SOC/SOH/SoH

Controls: charge/discharge current limits, voltage offset, force charge, enable/disable, charge scheduling, SOC limits

Installation

1. Clone: git clone https://github.com/Psynosaur/esphome-MitM-deye-jk-bms.git
2. Create secrets.yaml:

   wifi_ssid: "YourWiFiSSID"
   wifi_password: "YourWiFiPassword"
   api_key: "your-32-character-api-key"
   ota_key: "your-ota-password"

3. Adjust mitmdeye.yaml: IP address, current limits, entity IDs
4. Flash: esphome run mitmdeye.yaml
5. Connect hardware per connection diagram
6. Add to Home Assistant via ESPHome integration

Configuration

Shared settings

substitutions:
  offset_voltage: "0.4"      # Voltage drop compensation
  charge_current: "200"      # Max charge current (A)
  discharge_current: "200"   # Max discharge current (A)

Generating configs for N packs

Use add_packs.py to expand the deye_only.yaml template for any number of battery packs:

python add_packs.py --packs 4 -o deye_4packs.yaml
python add_packs.py                         # default 2 packs to stdout

Each pack maps to a CAN frame (Pack N = 0x14F + N). The script generates per-pack globals, CAN handlers (V/I/SOC/SOH extraction), template sensors, and SOC averaging logic. Max 16 packs (CAN 0x150-0x15F).

Home Assistant entities (JK BMS variant)

jk_bms_soc sensor must be exposed from your JK BMS via Home Assistant. Entity ID in YAML: sensor.jk_bms_state_of_charge.

Debugging

Set logger level to DEBUG for SOC values, CAN traffic, connection status, and filter logging.

Contributing

Fork, branch, test on hardware, submit PR.

License

MIT - see LICENSE.

Acknowledgments

• Adminius - original creator
• ESPHome and Home Assistant communities
• Deye/JK BMS communities for protocol documentation