This is purely speculation because we don't have the chargers to tear down. There could be a fault in the transformer, pushing a couple kilovolts AC into the power rectifier and shorting it, then pushing it straight into the dispenser and the car. However, for all we know it's the cars that are shorting themselves and taking 400 volts at full amperage and dying before the dispenser blows a breaker. I wouldn't be surprised if the cause was a battery fault either.

This is why I would love to see a tear down. What type of battery fault prevention is in an EA charger? What kind of step down system? Do they use a battery as a buffer? Just plain curious.