The Smart BMS from bmsbattery contains an OZ890 chip from O2Micro, which has the advantage that it can be custom programmed, calibrated and the chip data can be read out, such as the individual battery cell voltages:
The OZ890 debug software is free, but it only works with a special USB-I2C adapter, which costs $99 without shipping costs from China.
For those interested, I can borrow you my adapter for € 11.95 for one week, including shipping costs. The deposit is €50 which you get back after I received the adapter. You have to send back the adapter at your own expense. The shipping costs will be about €3; it fits in an envelope and the weight is less than 100g.
Note that, to save weight, the USB cable is not included:
Install the software, connect the adapter and run the program, that's all.