[TXnMA]

"Does this mean that cars (and so forth) will some day be powered by batteries that never need to be recharged? "

Well...yes... -- as long as you don't use them...

[Matchett-PI]

Thanks. So if one has “a battery that holds a charge forever” - forever merely means until he uses it. :)

“If, for example, a battery is left exposed to the air, the charge will eventually drain from it in a matter of days or weeks because the air is not a perfect insulator, according to Vinokur. “If you pass a current through a superconductor, then it will carry the current forever; conversely, if you have a superinsulator, then it will hold a charge forever,” he said.”