Eddy wrote:
So, are they fitting some kind of "eternal" self-charging battery inside
gadgets these days? If so, how "eternal" are they? What's their
life-span?

the last mains time switch I took apart after it died had a button cell
Ni-Cd battery on permanent float charge. Life seems to vary from months
to years, with random failures of either the float charging circuit or
the cell. A battery powered clock radio had a 100 microfarad electolytic
capacitor across the battery that normally powered the clock, which
showed correct time without a battery for a few minutes, unless the
radio was turned on....

--
Tciao for Now!

John.