It's here, it's real--the genset trailer for your Makita powered car...

Professor Fate said
From the story: "Little Generator Trailer Lets Electric Cars Go the Distance"
"If your battery starts running low, the EP Tender kicks into action, turning on the generator inside the trailer."

Were you clicking on my link from a reputable website or the OP's original link?
Definitely batteries in that trailer in my link.