You won't be able to warm your teapot with these rechargeable tealight candles, but they will stay aglow for a lot longer than traditional tealights. Made of plastic, these electric candles do not require fire to light up. They're programmed to flicker like actual tealights, in order to deliver the same ambiance but because these are much safer in settings with pets or children.
These flameless candles come with a plug-in tray that charges up to 12 candles at a time. When fully charged, they can stay lit for up to 12 hours. Each individual tealight has an on and off switch on the bottom.
Candles were historically used to sometimes provide heat or keep track of time. Though these aren't functional in that sense, the modern renditions are much more convenient to use.