I would like to mention your BMS model as supported. Could you provide a screenshot of the device info view of your android app or the "device info" response printed to the Esphome log on startup? Thanks in advance!

It worked but now i get an error while writing the image to the esp32.

INFO Uploading .esphome/build/jk-bms/.pioenvs/jk-bms/firmware.bin (1380288 bytes)
Uploading: [======================================================= ] 91%
ERROR Error sending data: [Errno 104] Connection reset by peer

Any recomendations?

The view I'm looking for is called "about" page:

The BLE connection is very resource hungry plus the coexisting of WiFi and BLE is challenging for a ESP32. You could add a safe mode reboot button to the configuration if OTAs are trouble some.

Yes, thank you very much!

This external component should work for your model but there are some devices out there which doesn't respond to UART traffic. Where did you buy the BMS?

From AliExpress
https://www.aliexpress.com/item/1005003719416234.html?spm=a2g0o.order_detail.order_detail_item.2.28b8f19czhULDW

The devices from Hankzor should work in general. What did you try exactly?

First I tested BT esp32-ble-example.yaml and it works perfectly,
then esp32-example.yaml.
I just changed the board to esp32doit-devkit-v1 but there is no communication on Rx.
So I researched further and found github://syssi/esphome-jk-bms@add-protocol-v4-support and tried it, there was communication on Rx but it looked like Echo Tx.
I will try another board and a shorter cable (now 1m) between BMS and ESP at the weekend.

This is the correct configuration example for your BMS model: https://github.com/syssi/esphome-jk-bms/blob/main/esp32-example.yaml

Please make sure to connect the ESP directly to the UART-TTL port of the BMS. Please avoid the RS484 dongle.