Implied Filling of Storage Battery

My question is based on this line of the changelog…
"Vehicle-mountable water tanks and kitchen units, implied storage-battery-charging generators."
Ok, I’ve found the RV Kitchen unit. Pretty cool. I have yet to use one. I assume the water tanks are mounted from metal tanks…? But my main question is what does the later half mean? Can storage batteries already be charged by generators or is it not in existence yet?

A storage battery mounted on a vehicle will be charged as the vehicle moves. (It’s only a trickle, so there’s no way to charge it enough to run an electric motor, but it will keep your RV Kitchen hot.)