As a kid, I had to replace these monsters that powered our household doorbells, I am no longer surprised by any size reductions or huge energy densities of modern batteries.
For example, I am amazed at how long the batteries in hobby drones last in those airborne videos.
And AFAIK, we're still getting signals from that interstellar space probe. Wow, like QRPness!
Oh, and I always feel obligated to bring up Dick Tracy's wrist radio and later wrist TV, so thanks, Hawkmoon!