I have a few NOCOs, but my experience has been the opposite. They just work for me. I keep one in all of my vehicles, plus a bigger one for tractors in my primary vehicle.I bought a NOCO brand jumper box a few years ago and paid too much for it, but it was a piece of crap and quit just after the warranty went out.
Mine worked great too until it didn’t.I have a few NOCOs, but my experience has been the opposite. They just work for me. I keep one in all of my vehicles, plus a bigger one for tractors in my primary vehicle.