Piper Archer - Headphones drains the battery ?

[Roy Page]

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.
I dismissed this caution as it did not seem to make any sense from an
electrical point of view.

When I came to start the engine yesterday, the cranking was very slow and
seemed like the battery was right down.
We have a new battery fitted a few months ago, so I doubt that as the
problem.
After flying for a couple of hours the engine cranking was back to its
normal speed.

I took a good look at the alternator and belt and nothing obvious was
noticed.
However, I noticed that a pair of unused headphones was plugged into a set
of the rear seat jack sockets.
They had been plugged in for about 2 weeks.

Now I wonder if they caused a slow drain on the battery while the bird sat
in the hanger for a couple of weeks ?

The aircraft has a SP400 intercom and an avionics master switch which is
always switched off when the engine is shut down.
The avionic line up is:-
KMA20, 2 x KX170's, KT76, KR86 and Flybuddy 820.

Maybe the old owner was correct ?
But what would cause the phones to take current off the battery ?

What does this knowledge base think ?


--
Roy
N5804F Piper Archer

"I have had some bad landings but I have never missed the runway"

[Tauno Voipio]

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.
> I dismissed this caution as it did not seem to make any sense from an
> electrical point of view.
>
> When I came to start the engine yesterday, the cranking was very slow and
> seemed like the battery was right down.
> We have a new battery fitted a few months ago, so I doubt that as the
> problem.
> After flying for a couple of hours the engine cranking was back to its
> normal speed.
>
> I took a good look at the alternator and belt and nothing obvious was
> noticed.
> However, I noticed that a pair of unused headphones was plugged into a set
> of the rear seat jack sockets.
> They had been plugged in for about 2 weeks.
>
> Now I wonder if they caused a slow drain on the battery while the bird sat
> in the hanger for a couple of weeks ?
>
> The aircraft has a SP400 intercom and an avionics master switch which is
> always switched off when the engine is shut down.
> The avionic line up is:-
> KMA20, 2 x KX170's, KT76, KR86 and Flybuddy 820.
>
> Maybe the old owner was correct ?
> But what would cause the phones to take current off the battery ?
>
> 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.

HTH

--

Tauno Voipio
tauno voipio (at) iki fi

[Jim Burns]

We once had an Archer II at the flight school that had a weird problem with
the clock circuit. The circuit was drawing wayyyyy more than it should and
would kill the battery overnight. The A&Ps never did find the problem, so
the fuse, located behind the baggage compartment bulkhead, was pulled.

Jim

[Darrel Toepfer]

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?

[mikem]

Unearth the aircraft battery, look to see if there are any connections
to the positive pole upstream from the master relay. You might find
one: the clock keep-alive circuit which should have a <1A cartridge
fuse in series with it. If there are any other connections upstream of
the master relay, you need to trace them to see where they go.

I have a SP400 intercom in my Pacer, and it is powered through its own
circuit breaker from the main avionics bus. With the master off, it is
unpowered, and it would not matter if headsets were plugged in or not.
It supplies the mic current to the backseat headsets, so if it is off,
they are off too. Sounds like some dumb**** who didn't have a clue
installed the intercom!

A common problem with older electrically-powered self-winding aircraft
clocks is that the winding solenoid intermitently sticks on, which will
run down your battery is short order.
As the clock spring runs down, a switch closes, applying power to a
solenoid, which is supposed to "wind UP" the spring, causing the switch
contact to open again. If the switch stays on, the solenoid remains
powered... Best fix is to chuck the mechanical clock and replace it
with a LCD pure electronic version...

[RST Engineering]

"mikem" > wrote in message
ups.com...
> Unearth the aircraft battery, look to see if there are any connections
> to the positive pole upstream from the master relay. You might find
> one: the clock keep-alive circuit which should have a <1A cartridge
> fuse in series with it. If there are any other connections upstream of
> the master relay, you need to trace them to see where they go.

I believe the certification regs allow up to a 5 amp breaker/fuse directly
from the battery for "keep alive".



With the master off, it is
> unpowered, and it would not matter if headsets were plugged in or not.
> It supplies the mic current to the backseat headsets, so if it is off,
> they are off too. Sounds like some dumb**** who didn't have a clue
> installed the intercom!

Amen to the dumb**** comment. The easy way to tell if this is a ds problem
is to get an aircraft mic plug (0.206" diameter) into the back seat mic
jack(s) and see if there is voltage with respect to airframe ground on
either of the two hot leads (ring or tip) with the master switch off. If
there is voltage present, read the paragraph above, especially the last
sentence. While I cannot conceive of voltage being on the aircraft phones
plug, just to satisfy the curious, do the same test on the hot lead of a
phones plug (0.250" diameter) plugged into the back seat jack(s)


>
> A common problem with older electrically-powered self-winding aircraft
> clocks is that the winding solenoid intermitently sticks on, which will
> run down your battery is short order.
> As the clock spring runs down, a switch closes, applying power to a
> solenoid, which is supposed to "wind UP" the spring, causing the switch
> contact to open again. If the switch stays on, the solenoid remains
> powered... Best fix is to chuck the mechanical clock and replace it
> with a LCD pure electronic version...

Many of the Target/K-Mart "travel alarm clocks" can be gutted and installed
into an old mechanical clock housing. They run from a single AA cell that
can be clipped to the back of the case. Change the battery every annual and
you don't have to have a keep-alive breaker/fuse installed at all.

Jim
>

[Roy Page]

The fountain of knowledge won out again.

I just checked the mike sockets, they are all Live with the master switch
off. !
Well the bird is going into the shop this coming week to have some other
poor wiring put back to standard so that is now on the list as well.
A previous installer really made a mess of the wiring when he put in the
wing strobes.
I won't go into details but the result was a toggle switch, poorly placed
next to the engine tach which controlled Nav lights and Strobes individually
on and off.
We are putting in the normal split switch to control beacon and strobes, and
returning the nav lights to the normal switch / dimmer control wheel.

Thanks for all the pointers and, as is often the case, Jim was on the money
once again.

--
Roy
N5804F Piper Archer

"I have had some bad landings but I have never missed the runway"


"RST Engineering" > wrote in message
...
>
> "mikem" > wrote in message
> ups.com...
>> Unearth the aircraft battery, look to see if there are any connections
>> to the positive pole upstream from the master relay. You might find
>> one: the clock keep-alive circuit which should have a <1A cartridge
>> fuse in series with it. If there are any other connections upstream of
>> the master relay, you need to trace them to see where they go.
>
> I believe the certification regs allow up to a 5 amp breaker/fuse directly
> from the battery for "keep alive".
>
>
>
> With the master off, it is
>> unpowered, and it would not matter if headsets were plugged in or not.
>> It supplies the mic current to the backseat headsets, so if it is off,
>> they are off too. Sounds like some dumb**** who didn't have a clue
>> installed the intercom!
>
> Amen to the dumb**** comment. The easy way to tell if this is a ds
> problem is to get an aircraft mic plug (0.206" diameter) into the back
> seat mic jack(s) and see if there is voltage with respect to airframe
> ground on either of the two hot leads (ring or tip) with the master switch
> off. If there is voltage present, read the paragraph above, especially
> the last sentence. While I cannot conceive of voltage being on the
> aircraft phones plug, just to satisfy the curious, do the same test on the
> hot lead of a phones plug (0.250" diameter) plugged into the back seat
> jack(s)
>
>
>>
>> A common problem with older electrically-powered self-winding aircraft
>> clocks is that the winding solenoid intermitently sticks on, which will
>> run down your battery is short order.
>> As the clock spring runs down, a switch closes, applying power to a
>> solenoid, which is supposed to "wind UP" the spring, causing the switch
>> contact to open again. If the switch stays on, the solenoid remains
>> powered... Best fix is to chuck the mechanical clock and replace it
>> with a LCD pure electronic version...
>
> Many of the Target/K-Mart "travel alarm clocks" can be gutted and
> installed into an old mechanical clock housing. They run from a single AA
> cell that can be clipped to the back of the case. Change the battery
> every annual and you don't have to have a keep-alive breaker/fuse
> installed at all.
>
> Jim
>>
>
>

[George Patterson]

Roy Page wrote:

> Maybe the old owner was correct ?

If he is, then something isn't wired properly. The first thing I would do is get
a schematic for the intercom wiring harness and check the power line for power
with the avionics master off.

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.

[Darrel Toepfer]

Roy Page wrote:

> The fountain of knowledge won out again.
>
> I just checked the mike sockets, they are all Live with the master switch
> off. !
> Well the bird is going into the shop this coming week to have some other
> poor wiring put back to standard so that is now on the list as well.

Just turn the intercom off for the time being when you aren't flying...

[George Patterson]

Darrel Toepfer wrote:

> Just turn the intercom off for the time being when you aren't flying...

*If* the power on the headset lines is coming through the intercom. It could be
coming from elsewhere; for example, from the radio "keep-alive" line. No telling
where Joe Fumblefingers crossed the wires up.

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.