DC fast chargers however have large, complex, high power switching circuitry that works at high duty cycles and often highish temperatures. It's not clear to me where most of the failures occur: at the customer interfacing unit with the plug, or in the back end with the power electronics, or with communications back to the mother ship. I imagine a lot of the trouble is with the plugs and cables, as these are handled by the public, are out in the weather, the cables get hot and most have coolant running through them, there is insertion and removal so some material erodes over time, and cars of many different manufacturers connect to that part of the circuit. There are also circuit breakers that can trip (legitimate and nuisance tripping), and some installations may have marginal electrical supply, and so on. There are fans that have filters that eventually clog up. Oh, and yobbos that press emergency stop buttons because they have nothing better to do, or that are told by social media that EVs are evil.
