On Wednesday, October 23, 2013 8:15:26 PM UTC-4, wrote:
if most transponders are not specially programmed (set up) they will
run all the time - they are "on" all of the time - drawing power even
when your panel read out says "off"

Say what ? A transponder should draw very little power except
when it is transmitting, which it only does when interrogated.
A Mode S transponder draws less than Mode C as it responds to
selective (fewer) interrogations (yes Daryll, I'm simplifying).
The only notable draw for a transponder installation would be a
poor quality encoder (older models have power-hungry heaters
rather than temperature-compensated altitude transducers);
should not be a problem for modern units...

Perhaps you can email me offline make/model of the setup
which gave you power problems?

Hope that helps,
Best Regards, Dave