Thanks, Alan.
Each loco has a battery car (disguised as an ordinary piece of rolling stock) behind it, with a 7.2v nicad pack inside -- the RC car kind. I slow charge the batteries overnight, get tons of run time, and can swap them between all the units. I tried track power but my four-wheel locos and harsh climate meant too many problems. I tried R/C, too, but it didn’t suit me. I like to watch trains; not play with them. Therefore, all my locos are controlled by simple switches that provide three forward speeds and two reverse (by rotating the smoke stack for example) with stop in the middle. That's just right for the amount of shunting I do, which normally means backing up, coupling to a car or two, running around in circles, then backing up and uncoupling.
