Just to close up this thread from my perspective:
Ecotality replaced my Blink. They concluded that the meter in the original was bad. The Sprig Electric tech got authorization to install powerline adapters (AHPE-303's) and a Cisco Valet wireless router. The unit is on an outside wall. The Valet communicates just fine through 5/8" of plywood exterior paneling on the garage, so Blink's wireless does work at very close range.
I join Valdemar in asking if I can plug in another powerline model, even manufacturer, of adapter and expect the 'master' that is connected to my main wireless router to provide another powerline connection? Any idea which are the 'critical' specs, I see a list of cryptically named modulation schemes under 'ethernet port' and some IEEE standard numbers. Is the chipset critical?