Donn,
I have a few of these newer lights (made by Roflan) and one was factory-made as a "power failure" light. It has power cord that plugs into a regular household receptacle. There is a relay inside so when the mains power fails, the light goes on. It still uses regular old 6V lantern batteries that are not rechargeable. There is a push-to-test button and a volt meter mounted in front of the handle above the sealed beam to test the voltage of the batteries.
Two of my lanterns came with "flood" lamps (they look like small car headlights) and another has a clear sealed bulb which has a pretty decent beam.
EIKO,
www.eiko-ltd.com , carries bulbs for these; part numbers are 4546 (clear lens, 4.7 volts, .50 Amps) or 4547 (clear lens, 4.75 volts, 1.25 Amps). I don't know if they sell to regular folks; my company buys from them for resale, so I just added on to a P.O. and paid the company back. Or you could google for PAR 36 lamps.
I have seen these lanterns in yellow, gray, and a light, pastel green.
Kirk