A new study indicates that an average of 20% of electric vehicle chargers will be non-operational at any given time. Now as someone who's worked in electronics reliability for the past 25 years or so, I've got a few thoughts on this. First of all, as you might guess, a 20% offline rate means that necessary margin is not built into the product. It is analogous to the failure rate of race cars, really, and is something you would never accept for your Camry or Golf Sportwagen (my car). This is especially bad when one realizes that a charger is not exactly a complicated piece of equipment; it's a heavy duty DC power supply with a meter, a microprocessor, a screen, and a few buttons. The meter on your home, combined with the transformer on the pole or in the green box nearby, serves much the same function, just with alternating current.
So what is going on with electric car chargers? Really, the same thing that I noticed 12 years back with CFL lightbulbs (rest in the toxic waste dump), that because getting the product out there was so politically important and urgent, they didn't do the correct reliability engineering or testing. Then combine that with the fact that they're often in the worst possible setting, like a garage without ventilation, or worse yet in the sun with no active cooling for the transformer and power supply. I'm guessing the inner components may be getting hot enough to "leave skin behind" if you were unlucky enough to touch them, and suffice it to say this kills electronics reliability. The old engineer's adage was that 5C increase in temperature halved the life of any device, and we're talking probably five to ten times that amount.
In other words, electric car chargers are a lot like older Ferraris, looking very sleek and fashionable, but really bound to spend a lot more time at the repair shop than actually doing their job. It's yet another reason to get government out of the business of deciding what we drive.