ve3... wrote:

About ten years ago I got a batch of heavy-duty Radio Shack Ni-Cads
rated at 5,000 mah. They were quite satisfactory but were a bit fiddly
to recharge correctly.

Are you sure about the 5000-mah capacity of those Radio Shack NiCd's?
The highest capacity 'D' cell NiCd's I ever saw at Radio Shack were
4500-mah. I still have a set of Panasonic 'D' cell NiCd's which are
rated at 5000-mah. They're about eight years old and still going strong.
I payed about $11.00-US each. Now you can get NiMH's in that price range
with much higher capacities.