Because I'm not sure ????

All PS-3's (sorry, forgot to mention)

It shouldn't cause damage, the one downside is as Sam pointed out, the chrono runs.

As others have already stated, no harm will be done leaving them powered, but if you could install a switch on the sidings you could shut them off while still running one on the loop. That's what I do here to keep them 'off the clock' so to speak. PS-3's don't have batteries, no worries there about charging.

When you want to run one of the ones sitting, just flip the switch to power the track, select the engine and hit the start button to get them out of conventional mode and you are ready to go. If everything else has already been started up when you power the siding the engine will start in conventional mode as it has missed the watchdog signal. Pressing the start button puts it back into command mode. If you want it in command mode and not running, press the shut down button. 

I remember when DCS first came out, that was one of the benefits advertised, you didn't need blocks or dead sidings. Then someone found out the clock runs.  I'm just now getting around to isolating my sidings and spurs, saves the lighted cars. hasn't hurt my trains but then I don't run trains very often. Maybe one or two hours a month.

Clem

Thanks....

That's just the info I needed. It sorta' follow, since I've not seen any warnings or horror stories, but protecting my assets (locos) takes precedence over my fear of asking a dumb question.

Personally, I don't mind if the "clock runs" even when not in use. My enjoyment ranks higher than any potential resale value at an "estate sale" when I'm gone.

Also note: Plans are in the formative stage for layout enlargement, so wiring in some

switched sidings (I/O) will be part of the plan.

Thanks for the 9nfo..

Jeff