@pito
I already considered this because the code currently in here is too complex. As written above - I assume to have tracked the issue down to serial communication (reading + processing BMS data and writing the corresponding output to serial output / USB) because my sketch works without any problems (tested for > 24h) if I simply comment out the corresponding few lines of code triggering these functions.
But I will try to build a much simpler sketch containing only those serial communication functions without any measuring and logging in order to find out if the freezes are really only caused by this...
Thanks for your thought - I will keep you posted !