Tauno Voipio wrote:

Roy Page wrote:

When we bought our Piper Archer 2 years ago the previous owner
cautioned about leaving headphones plugged in in the rear seats.
He reckoned that with the headphones plugged in the battery would be
slowly drained.

What does this knowledge base think ?

If there is a microphone (for intercom) the
headphones can use a little of current, provided
the intercom is on. IMHO, it is miswired if
it gets power when the battery relay (and switch)
is off.

In many airplanes, the clock gets power even with
the main switch off.

To verify, you need to switch the battery switch
off and measure the battery current with a suitable
ammeter - the built-in one is far too coarse for this.

Can you talk over the intercom with the master off? What about the rear
seats?