If you thought the solution to making long journeys with your all-electric vehicle was to simply buy one with better range, it seems that you were somewhat mistaken.
EP Tender attached their B00 range extender system to a Renault Zoe and drove 570 km (354 miles) to Geneva, thus proving that the concept is solid and the trailer can be used in a very practical capacity.
In a recent interview, even Tesla CEO Elon Musk said that he toyed around with the idea of adding a trailer with an auxiliary battery pack, since one of his goals was actually to not give his cars so much autonomy (which meant bigger & heavier batteries) that they wouldn't actually use all of it most of the time.
If we look at it that way, we can certainly find ways in which to appreciate the concept of logging around a small trailer providing you with extra charge, though it depends on personal preference, since there are plenty of alternatives such as building a proper charging network.
Odds are, car manufacturers will keep focusing on making electric cars simply better at covering longer distances and keep accessories such as the EP Tender strictly on their drawing boards.