Selyn-powered devices, and selyn batteries became common as simes and Gens rediscovered the technology of the Ancients.
According to our index card file, in Operation HIghTime -- http://www.simegen.com/sgfandom/rimonslibrary/oht.html the following items were selyn-powered in the general scheme of life at the time: door locks, stove, heater, lights, refrigerator, helicopter. Probably 60% of electricity used to light up Washington was created using selyn (which is later considered an abysmal waste of selyn as it can be used directly rather than converted into electricity).
"...The ranch had always been our weekend retreat. We allowed no life-powered services, preferring to use mechanical door locks, a petro-chemical stove and heater, electrochemical lights, and a really ancient ice box--no power just ice. We got along well without hot running water and vigorously enforced our ban on all powered communications instruments, public and private..."
(Source: Index card file. Operation High Time -- http://www.simegen.com/sgfandom/rimonslibrary/oht.html --- Helicopter) Selyn-powered: "three dynopter fields." Two-seater. Could travel cross-country by hopping from sime Territory to sime Territory, taking on new selyn-packed batteries (Mairis does so) used to land at special copter ports, but development of "ground-effect landing" made it reasonable to land in town.
(Source: Index card file, The Channel's Exemption -- http://www.simegen.com/sgfandom/rimonslibrary/ce.html -- Technology)
Porta-tents: a thin film of shiny material on one side, black on the other, powered by a small selyn battery. Both self cooling and very efficient heat pump.
Fire-strikers: A wand that is selyn-powered
Vibro-blade: A selyn-powered cutting tool
Starship and lifeboat