Poor quality control. The unit didn't work when it arrived, but I was in the middle of moving and packed it somewhere. After two years I found it and decided to reuse ultracapacitors for another project. During disassembly I found a cracked solder joint, so the positive pole was not connected to the circuit board, but only to the electromagnetic switch. Bad design, bad soldering, no quality control. After I soldered another longer connector it works fine. I can add a small switch to start the…