Cherokee battery box repair

Hey all... I've got the plane down for an annual and have discovered a small
weeping leak in the bottom of the battery box (where the drain nozzle attaches). Am I
correct in recalling that the box is made of tin and the nozzle of copper? Will
regular Lead/Tin (60/40) solder this, or do I need some special solder for it? It
seems like it should be repairable, since it looks like it was *made* by soldering.

Oh yeah, and of course a good cleanup and repaint is in order back there.
Very little corrosion back there, but enough to do a bit of cleanup.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

The battery boxes that I have seen are made of aluminium.

Mike
MU-2

wrote in message
...
Hey all... I've got the plane down for an annual and have discovered a
small
weeping leak in the bottom of the battery box (where the drain nozzle
attaches). Am I
correct in recalling that the box is made of tin and the nozzle of copper?
Will
regular Lead/Tin (60/40) solder this, or do I need some special solder for
it? It
seems like it should be repairable, since it looks like it was *made* by
soldering.

Oh yeah, and of course a good cleanup and repaint is in order back there.
Very little corrosion back there, but enough to do a bit of cleanup.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

So far there's one vote for aluminum, one for stainless, and one for tin, eh?
I'm sure it depends on which aircraft and model year, but I'm sure hoping I can get
away with some form of solder. A friend of mine had to fix his '65 Cherokee 150's
box... probably the same as my '69. He got some funky solder/brazing rod that
apparently worked on his. What I see on min is not magnetic, but doesn't look like
aluminum either. Seems too heavy to be aluminum, although I haven't removed the
solenoid from the side of the box yet, either.

Speaking of that, anyone figured out the purpose of the diode and resistor
back there on that vintage PA-28? As near as I can tell from the schematic, it allows
the alternator to slowly charge a completely dead battery with the master off.
Then will allow the alternator/partially charged battery to close the master and
charge it properly. Of course all this would require the alternator to self-excite...
something I didn't think they were typically set up to do. Thoughts?

I just figured I'd ping the collective wisdom here since I'm sure lots of
folks have dealt with it. I just didn't like the idea of weeping battery acid on the
airframe. Since I broke it further upon removal, now I *have* to fix it.

-Cory

Aaron Coolidge wrote:
: wrote:
: : Hey all... I've got the plane down for an annual and have discovered a small
: : weeping leak in the bottom of the battery box (where the drain nozzle attaches). Am I
: : correct in recalling that the box is made of tin and the nozzle of copper? Will
: : regular Lead/Tin (60/40) solder this, or do I need some special solder for it? It
: : seems like it should be repairable, since it looks like it was *made* by soldering.

: My Cherokee's battery box is made of stainless steel. It also had a little
: seepage at the drain tube. Someone had brazed (!) a galvanized (!) pipe
: flange onto it, and threaded a little 1/8" pipe nipple into it. The braze
: broke off the battery box (go figure).

: I TIG welded a patch onto the bottom, and TIG welded a little length of
: 316 stainless pipe to the bottom of the box. All is now well.

: --
: Aaron C.

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...

Speaking of that, anyone figured out the purpose of the diode and resistor
back there on that vintage PA-28? As near as I can tell from the
schematic, it allows
the alternator to slowly charge a completely dead battery with the master
off.
Then will allow the alternator/partially charged battery to close the
master and
charge it properly. Of course all this would require the alternator to
self-excite...
something I didn't think they were typically set up to do. Thoughts?

I've always assumed they were there to prevent the volotage induced by the
collapsing magnetic field around the solenoid from spiking the electrical
system.

John Kunkel wrote:
: I've always assumed they were there to prevent the volotage induced by the
: collapsing magnetic field around the solenoid from spiking the electrical
: system.

I don't think so for two reasons:
1. The starter operating would require the master solenoid to be closed, so the
diode/resistor pair is shorted out and not a factor.
2. The direction of the diode is the wrong way to be a path for flyback current in the
starter solenoid.

Assuming the master solenoid stays closed, the battery should do a pretty good
job of absorbing voltage transients from the starter.

Good theory though.... I'm sure there are some setups where it's set up that
way... I just don't think this is one of them.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

I don't know Cherokee electrics, but does it maybe offer a way to (very
slowly) charge the battery thru the external service plug?

My Cessna 172M has a funny diode-resistor circuit like that in the
battery circuit in which that's the only reason I can see for it. It
is not described in the POH or even the service manual. Otherwise with
a completely dead battery, if I used the ground service plug to start
it, there still wouldn't be anything in the battery to initialize the
alternator.

Flyback diodes don't usually have a resistor in series with them.

Another good idea, but the schematic has rather clearly shown the
diode/connector setup for the external connection, but has it shown as "optional."
This diode/resistor is in addition to that.

nrp wrote:
: I don't know Cherokee electrics, but does it maybe offer a way to (very
: slowly) charge the battery thru the external service plug?

: My Cessna 172M has a funny diode-resistor circuit like that in the
: battery circuit in which that's the only reason I can see for it. It
: is not described in the POH or even the service manual. Otherwise with
: a completely dead battery, if I used the ground service plug to start
: it, there still wouldn't be anything in the battery to initialize the
: alternator.

: Flyback diodes don't usually have a resistor in series with them.


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...
So far there's one vote for aluminum, one for stainless, and one for tin,
eh?
I'm sure it depends on which aircraft and model year, but I'm sure hoping
I can get
away with some form of solder. A friend of mine had to fix his '65
Cherokee 150's
box... probably the same as my '69. He got some funky solder/brazing rod
that
apparently worked on his. What I see on min is not magnetic, but doesn't
look like
aluminum either. Seems too heavy to be aluminum, although I haven't
removed the
solenoid from the side of the box yet, either.

Speaking of that, anyone figured out the purpose of the diode and resistor
back there on that vintage PA-28? As near as I can tell from the
schematic, it allows
the alternator to slowly charge a completely dead battery with the master
off.
Then will allow the alternator/partially charged battery to close the
master and
charge it properly. Of course all this would require the alternator to
self-excite...
something I didn't think they were typically set up to do. Thoughts?

Hence the term : "Alternator Source- Power Relay energizing circuit"
used by Piper, in my Cherokee's Operating Manual



-Cory

Aaron Coolidge wrote:
: wrote:
: : Hey all... I've got the plane down for an annual and have
discovered a small
: : weeping leak in the bottom of the battery box (where the drain nozzle
attaches). Am I
: : correct in recalling that the box is made of tin and the nozzle of
copper? Will
: : regular Lead/Tin (60/40) solder this, or do I need some special solder
for it? It
: : seems like it should be repairable, since it looks like it was *made*
by soldering.

: My Cherokee's battery box is made of stainless steel. It also had a
little
: seepage at the drain tube. Someone had brazed (!) a galvanized (!) pipe
: flange onto it, and threaded a little 1/8" pipe nipple into it. The
braze
: broke off the battery box (go figure).

: I TIG welded a patch onto the bottom, and TIG welded a little length of
: 316 stainless pipe to the bottom of the box. All is now well.

: --
: Aaron C.

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
...
John Kunkel wrote:
: I've always assumed they were there to prevent the volotage induced by
the
: collapsing magnetic field around the solenoid from spiking the
electrical
: system.

I don't think so for two reasons:
1. The starter operating would require the master solenoid to be closed,
so the
diode/resistor pair is shorted out and not a factor.
2. The direction of the diode is the wrong way to be a path for flyback
current in the
starter solenoid.

I was thinking of the collapsing field around the master contactor solenoid.

On Mon, 29 Aug 2005 12:59:09 +0000 (UTC),
wrote:

Hey all... I've got the plane down for an annual and have discovered a small
weeping leak in the bottom of the battery box (where the drain nozzle attaches). Am I
correct in recalling that the box is made of tin and the nozzle of copper? Will
regular Lead/Tin (60/40) solder this, or do I need some special solder for it? It
seems like it should be repairable, since it looks like it was *made* by soldering.

Oh yeah, and of course a good cleanup and repaint is in order back there.
Very little corrosion back there, but enough to do a bit of cleanup.

-Cory


Solder should work fine. My '67 Cherokee needed fixing last year and
that's how I took care of it.

HTH.
z