After Yellowstone, people couldn’t get more supercars so they just kept charging the old ones while whispering prayers to whatever they thought will listen. Amazingly, the caps not only held up but some of those originals are still in use today. No other race, elder or not, even wants to try. The last Xx scientist who researched the tech had to be dragged to the recovery gardens. He was reported as being heard screaming “Electrons aren’t electrons!” at the top of his voice while rubbing sheets of aluminum foil over his. Naked body as he ran around a rather prestigious university during admissions week.
Well, at least the humans kept the knowledge going. Who knows, maybe in a far future when the grandchildren of those who lived through the Sol Wars are dead and buried then maybe, just maybe, humanity becomes whole again. Probably not for a thousand years after that, but who knows? Then again maybe one of those original lab techs writes everything down and teaches others for the sake of doing the impossible. Row fight the! They haven’t lost it yet. I mean, they still have the detailed (with all of the secrets) on file. The skill to actually pull it off, however, isn’t being maintained.