Batteries

It's a milestone blip today.

So, keeping with the tradition from my 365th, here's a puzzle.
OK it was inspired by ~scottmliddell and his milestone, and related to ~wintersixfour's lazy blip at the weekend.

Can you guess what it is yet?

So, I suppose it's yet another chance to shamelessly plug my puzzle site - try it, it's free to register and play!