That was a mistake by me in the design process - I simply forgot, that the charge voltage of battery systems are 14.7 V - And when I tested the diodes, they were not very happy getting more than 13 V.

We should have gotten a stack of cheap DC-DC converters to keep the voltage at 12 V for each strand of Diodes. But we realized the mistake too late for another Aliexpress-order, so we just had to go with a solution with parts from our stock.

..next year we will have lots of better ways to do things.