Eastburn wrote:
I think it is a energy cell that is akin to a capacitor and a battery.

Really it is a super capacitor that is low leakage. Maybe a 1F at 1V.

Nope.
It's a 1/6th (or so) AAA NiCd cell.

THey have been made for 30 or more years and have found a niche market
at last!

The sort of low-ESR supercapacitor that you are referring to has only
been commercially available for 6 years or so.
The ones in most VCRs as capacitors to keep the clock alive over power
outages have a maximum current of a couple of milliamps.