Cannot connect JK BMS W19

[MTBMichal]

Checklist

• I need support with using the integration.
• My issue is not a feature request
• I have thought about providing a debug log and/or diagnostic data.

Describe the issue

Hi

I have a problem trying to use this integration, it cannot connect to JK BMS.
I'm attaching an extract from the debug log when trying to add the device, I extracted lines containing jikong_bms and the BT address A4:C1:38:02:2E:F3.

Perhaps this line is interesting

[aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: unexpected message type 0xC8 (length 20): bytearray(b'\xaaU\x90\xeb\xc8\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00D')

ha_jk.log

[patman15]

Hi!
Your RSSI is strangely high, which hints to interference with other devices. Do you have the BMS very close to your Bluetooth dongle? You should have >1m I would guess. I can see that there are connection issues:

2026-01-01 16:14:23.242 DEBUG (MainThread) [bleak_retry_connector] A4:C1:38:02:2E:F3 - A4:C1:38:02:2E:F3: Failed to connect: No backend with an available connection slot that can reach address A4:C1:38:02:2E:F3 was found, device_missing: False, backing off: 4.0 (attempt: 2, last rssi: None)
2026-01-01 16:14:23.242 DEBUG (MainThread) [bleak_retry_connector.bluez] 508279G49103635-00 - A4:C1:38:02:2E:F3: Device was removed from bus at /org/bluez/hci0/dev_A4_C1_38_02_2E_F3, waiting 4.0 for it to re-appear: (<class 'bleak.exc.BleakError'>) device 'dev_A4_C1_38_02_2E_F3' not found

or probably you have other high disturbances that influence the connection.

[MTBMichal]

Hi, yes the BMS is pretty close to the PC. It's connected to 2 other BMS that are there as well - Seplos V2. Those work OK.
It used to work just fine with older JK BMS.
Connecting to the BMS by phone works OK.

It's my brother's setup and he's tried to uninstall the integration and put it back. He didn't add the Seplos BMS for now, just tried adding the JK one. We get a different error

2026-01-02 17:31:04.202 DEBUG (MainThread) [custom_components.bms_ble] Setup of <ConfigEntry entry_id=01KDX1YH49199GN5XNM5K16BH6 version=2 domain=bms_ble title=508279G49103635-00 state=ConfigEntryState.SETUP_IN_PROGRESS unique_id=A4:C1:38:02:2E:F3>
2026-01-02 17:31:04.202 DEBUG (MainThread) [aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: initializing Jikong smart BMS, BT address: A4:C1:38:02:2E:F3
2026-01-02 17:31:04.203 DEBUG (MainThread) [custom_components.bms_ble] Initializing coordinator for 508279G49103635-00 (A4:C1:38:02:2E:F3) as Jikong smart BMS
2026-01-02 17:31:04.203 DEBUG (MainThread) [custom_components.bms_ble] 508279G49103635-00: advertisement: {'name': '508279G49103635-00', 'address': 'A4:C1:38:02:2E:F3', 'rssi': -64, 'manufacturer_data': {2917: b'\x88\xa0\xa4\xc18\x02.\xf3'}, 'service_data': {}, 'service_uuids': ['0000ffe0-0000-1000-8000-00805f9b34fb', '0000fee7-0000-1000-8000-00805f9b34fb'], 'source': '60:45:2E:71:50:65', 'advertisement': AdvertisementData(local_name='508279G49103635-00', manufacturer_data={2917: b'\x88\xa0\xa4\xc18\x02.\xf3'}, service_uuids=['0000ffe0-0000-1000-8000-00805f9b34fb', '0000fee7-0000-1000-8000-00805f9b34fb'], tx_power=-127, rssi=-64), 'device': BLEDevice(A4:C1:38:02:2E:F3, 508279G49103635-00), 'connectable': True, 'time': 715.651901802, 'tx_power': None, 'raw': b'\x02\x01\x06\x05\x02\xe0\xff\xe7\xfe\x0b\xffe\x0b\x88\xa0\xa4\xc18\x02.\xf3\x13\t508279G49103635-00'}
2026-01-02 17:31:04.203 DEBUG (MainThread) [aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: connecting BMS
2026-01-02 17:31:04.204 DEBUG (MainThread) [bleak_retry_connector] A4:C1:38:02:2E:F3 - A4:C1:38:02:2E:F3: Connection attempt: 1
2026-01-02 17:31:04.204 DEBUG (MainThread) [bleak_retry_connector] 508279G49103635-00 - A4:C1:38:02:2E:F3: No cached services found for device path /org/bluez/hci0/dev_A4_C1_38_02_2E_F3
2026-01-02 17:31:04.941 DEBUG (MainThread) [bleak_retry_connector] A4:C1:38:02:2E:F3 - A4:C1:38:02:2E:F3: Connected after 1 attempts
2026-01-02 17:31:04.941 DEBUG (MainThread) [aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: failed to detect characteristics.
2026-01-02 17:31:06.834 DEBUG (MainThread) [aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: disconnected from BMS
2026-01-02 17:31:06.836 INFO (MainThread) [aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: failed to initialize BMS connection (ConnectionError)
2026-01-02 17:31:06.836 DEBUG (MainThread) [aiobmsble.bms.jikong_bms] 508279G49103635-00|2EF3: disconnecting BMS (False)
2026-01-02 17:31:06.837 ERROR (MainThread) [custom_components.bms_ble] Unexpected error fetching 508279G49103635-00 data
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/helpers/update_coordinator.py", line 357, in __wrap_async_setup
    await self._async_setup()
  File "/config/custom_components/bms_ble/coordinator.py", line 114, in _async_setup
    bms_info: Final[BMSInfo] = await self._device.device_info()
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.13/site-packages/aiobmsble/basebms.py", line 175, in device_info
    await self._connect()
  File "/usr/local/lib/python3.13/site-packages/aiobmsble/basebms.py", line 374, in _connect
    await self._init_connection()
  File "/usr/local/lib/python3.13/site-packages/aiobmsble/bms/jikong_bms.py", line 180, in _init_connection
    raise ConnectionError(f"Failed to detect characteristics from {self.name}.")
ConnectionError: Failed to detect characteristics from 508279G49103635-00.

[patman15]

Uninstalling and re-installing doesn't help the hardware connection issues, so I fear this cannot help.
The error just says that the device couldn't be discovered properly, so again most likely an interference issue, not a software problem.

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[github-actions]

This issue was closed because it has been stalled for 8 days with no activity.