Electrical "issues" while IFR (long post)

[Ted Waltman]

I have the Jasco 7555T alternator & J12M24SP voltage regulator in my
Moose with the M-14P engine.

All my flight instruments are electrical (e.g. the Attitude & Turn/Bank
Indicator in particular). Maybe you can see where this story is
going...

Leaving Denver for Iowa 10 days ago (on the way to Oshkosh), I filed IFR
to try to get above a nasty weather system grounding all VFR traffic.
About 30 min after takeoff I broke out above the clouds. All was great,
until I noticed my engine monitor reporting 1, 0, -1 then -2 amps. My
ammeter sensor is on the main current carrying wire out of the
alternator, measuring total amp output from the alternator. Within 5 to
10 minutes I got a "Low Battery" warning. Less than a minute later
(well it seemed like less than a min) everything went South...I lost all
flight & engine instruments.

I got out my handheld radio (sure glad I had it) to get back in contact
with Center. At this point I was also wishing I had my handheld GPS
with me (I left it home thinking, "Who needs it with two panel mount
GPS's in the plane?"). The clouds were rising in front of me; behind me
was solid IFR down to minimums in the Denver area. I talked to Center,
told them I could not, NOT, go into the clouds period. I climbed to 10,
then 11, 12, 14, 15...up to 16,000' trying to stay above the weather.
Center was trying to find me a hole somewhere up ahead to get down
through. Finally I reset the alternator breaker multiple times and at
least got the system running long enough to spin up the turn & bank
indicator. I decided to take a chance on flying partial panel at a
lower altitude rather than waiting to pass out from lack of oxygen up at
16,000'. Down in the clouds and about 20 minutes later I broke out
between layers. Guess I passed the partial panel IFR test on that
flight.

Center gave me vectors to the McCook Nebraska area where there was a
hole. Here's the first weird thing...about 5 minutes outside of McCook
I reset the alternator breaker (for about the 20th time) and everything
acted normal...normal amps, power, voltage, the works. When I landed at
McCook Nebraska there were cops, fire trucks and the works there. Glad
my wife wasn't with us. Maintenance folks at McCook looked at the
alternator & regulator; all seemed Ok.

Later in the evening the weather was perfect VFR, so I decided to
continue to Iowa where I could spend more time at the in-law's
troubleshooting the system. When I took off from McCook the alternator
was showing 6 amps (normal). Every 10 to 20 minutes the amps dropped by
1, eventually getting to zero. So I shut everything down and flew
pilotage to Iowa.

I talked to the Jasco folks re the alternator & voltage regulator. All
we could find was one wire that was showing a slight drop in voltage
from the regulator to the alternator. Replaced this and thought the
problem was fixed, as all was fine for 5+ hours to/from OSH from Iowa.
However, problem acted up again on way back to Colorado (maybe it's the
altitude <grin>, heat or vibration). Battery is showing that it is
maintaining it's charge, but amps drop from normal ~5 to perhaps 1, 0,
-1, -2 and all around that area. Amps start dropping perhaps 10 min
after takeoff and drop in a linear fashion every 10 or so minutes after
that.

I've downloaded the Jasco wiring diagrams and troubleshooting charts.
Has anyone every heard of a problem like this? Any ideas? The Jasco
folks hadn't heard of a system showing degrading amps like this.

As Paul Harvey says, "Now for the rest of the story." My two teenage
boys, who were with me, and I decided not to tell my wife (at least for
a while anyway). So we got to Iowa, called home and said we had an "Ok"
flight. The next day I'm working on the plane with a buddy of mine in
Iowa and I get a call on my cell phone from a # I didn't recognize. The
person introduces himself as a Delta pilot who was at 37,000' feet the
day before, heard my situation, and spotted the hole that Center
eventually routed me to. I thanked the Delta pilot profusely of course.
He then says, "I'll bet you're wondering how I got your phone number?"
He said he looked up my N # on the web, looked my name with the address
on the web and got my home #. Yep, he told my wife!

Ted
Moose N142SR




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[Bob Patterson]

Hi Ted !

Quite a story !!! Sure got my hair standing up !! :-)

Just one thought - you don't, by chance, have a 'deep-cycle'
or similar type of battery ??? These might be acting up when
fully/over charged .... Or maybe have a bad cell that reacts
to altitude ??? I've had altitude-related ignition problems
that were very hard to trace - changing plugs finally solved
it, although nobody could tell me why (the orig. plugs had only
about 50 hours on them !).

Just throwing out ideas ....

.....bobp

------------------------------orig.-----------------------
At 08:55 PM 8/4/04 -0600, you wrote:

I have the Jasco 7555T alternator & J12M24SP voltage regulator in my
Moose with the M-14P engine.

All my flight instruments are electrical (e.g. the Attitude & Turn/Bank
Indicator in particular). Maybe you can see where this story is
going...

Leaving Denver for Iowa 10 days ago (on the way to Oshkosh), I filed IFR
to try to get above a nasty weather system grounding all VFR traffic.
About 30 min after takeoff I broke out above the clouds. All was great,
until I noticed my engine monitor reporting 1, 0, -1 then -2 amps. My
ammeter sensor is on the main current carrying wire out of the
alternator, measuring total amp output from the alternator. Within 5 to
10 minutes I got a "Low Battery" warning. Less than a minute later
(well it seemed like less than a min) everything went South...I lost all
flight & engine instruments.

I got out my handheld radio (sure glad I had it) to get back in contact
with Center. At this point I was also wishing I had my handheld GPS
with me (I left it home thinking, "Who needs it with two panel mount
GPS's in the plane?"). The clouds were rising in front of me; behind me
was solid IFR down to minimums in the Denver area. I talked to Center,
told them I could not, NOT, go into the clouds period. I climbed to 10,
then 11, 12, 14, 15...up to 16,000' trying to stay above the weather.
Center was trying to find me a hole somewhere up ahead to get down
through. Finally I reset the alternator breaker multiple times and at
least got the system running long enough to spin up the turn & bank
indicator. I decided to take a chance on flying partial panel at a
lower altitude rather than waiting to pass out from lack of oxygen up at
16,000'. Down in the clouds and about 20 minutes later I broke out
between layers. Guess I passed the partial panel IFR test on that
flight.

Center gave me vectors to the McCook Nebraska area where there was a
hole. Here's the first weird thing...about 5 minutes outside of McCook
I reset the alternator breaker (for about the 20th time) and everything
acted normal...normal amps, power, voltage, the works. When I landed at
McCook Nebraska there were cops, fire trucks and the works there. Glad
my wife wasn't with us. Maintenance folks at McCook looked at the
alternator & regulator; all seemed Ok.

Later in the evening the weather was perfect VFR, so I decided to
continue to Iowa where I could spend more time at the in-law's
troubleshooting the system. When I took off from McCook the alternator
was showing 6 amps (normal). Every 10 to 20 minutes the amps dropped by
1, eventually getting to zero. So I shut everything down and flew
pilotage to Iowa.

I talked to the Jasco folks re the alternator & voltage regulator. All
we could find was one wire that was showing a slight drop in voltage
from the regulator to the alternator. Replaced this and thought the
problem was fixed, as all was fine for 5+ hours to/from OSH from Iowa.
However, problem acted up again on way back to Colorado (maybe it's the
altitude <grin>, heat or vibration). Battery is showing that it is
maintaining it's charge, but amps drop from normal ~5 to perhaps 1, 0,
-1, -2 and all around that area. Amps start dropping perhaps 10 min
after takeoff and drop in a linear fashion every 10 or so minutes after
that.

I've downloaded the Jasco wiring diagrams and troubleshooting charts.
Has anyone every heard of a problem like this? Any ideas? The Jasco
folks hadn't heard of a system showing degrading amps like this.

As Paul Harvey says, "Now for the rest of the story." My two teenage
boys, who were with me, and I decided not to tell my wife (at least for
a while anyway). So we got to Iowa, called home and said we had an "Ok"
flight. The next day I'm working on the plane with a buddy of mine in
Iowa and I get a call on my cell phone from a # I didn't recognize. The
person introduces himself as a Delta pilot who was at 37,000' feet the
day before, heard my situation, and spotted the hole that Center
eventually routed me to. I thanked the Delta pilot profusely of course.
He then says, "I'll bet you're wondering how I got your phone number?"
He said he looked up my N # on the web, looked my name with the address
on the web and got my home #. Yep, he told my wife!

Ted
Moose N142SR




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[N.Smith]

Hi Ted

I'm far from an expert...but if the ammeter in the engine monitor is showing
a minus current, the flow must be from battery (and bus) to generator side
of the shunt that the ammeter is connected to.

Not quite sure how your setup is, but assuming alternator - regulator -
shunt - bus, then for the ammeter across the shunt to detect a negative
current there must be a load instead of a supply on the regulator /
generator that is being supplied by the battery in addition to all your
normal bus demands (hence a battery low volts after a while).

If you only have JASCO bits between the engine and the shunt then it's a
JASCO bit that's at fault (or possibly wiring between them).

The Alternator probably has a rectifier diode array built in, and if one or
more of these diodes is faulty then that could cause the problem (although
it's also possible a faulty regulator could shut off the output current from
the alternator as well).

Having checked all wiring connected to the alternator and regulator for any
shorts to airframe or intermittent open circuits..,if possible I'd change
one item (alt or reg) and see if that cures your problem.

I don't think you need look at any other part of your electrical system.

Just my 2 cents worth (about 1 UK pence at current exchange rates :-) )

Nigel
Elite 745E
Derby

PS...great story well told



-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of Ted
Waltman
Sent: 05 August 2004 03:56
To: rebel-builders@dcsol.com
Subject: Electrical "issues" while IFR (long post)


I have the Jasco 7555T alternator & J12M24SP voltage regulator in my
Moose with the M-14P engine.

All my flight instruments are electrical (e.g. the Attitude & Turn/Bank
Indicator in particular). Maybe you can see where this story is
going...

Leaving Denver for Iowa 10 days ago (on the way to Oshkosh), I filed IFR
to try to get above a nasty weather system grounding all VFR traffic.
About 30 min after takeoff I broke out above the clouds. All was great,
until I noticed my engine monitor reporting 1, 0, -1 then -2 amps. My
ammeter sensor is on the main current carrying wire out of the
alternator, measuring total amp output from the alternator. Within 5 to
10 minutes I got a "Low Battery" warning. Less than a minute later
(well it seemed like less than a min) everything went South...I lost all
flight & engine instruments.

I got out my handheld radio (sure glad I had it) to get back in contact
with Center. At this point I was also wishing I had my handheld GPS
with me (I left it home thinking, "Who needs it with two panel mount
GPS's in the plane?"). The clouds were rising in front of me; behind me
was solid IFR down to minimums in the Denver area. I talked to Center,
told them I could not, NOT, go into the clouds period. I climbed to 10,
then 11, 12, 14, 15...up to 16,000' trying to stay above the weather.
Center was trying to find me a hole somewhere up ahead to get down
through. Finally I reset the alternator breaker multiple times and at
least got the system running long enough to spin up the turn & bank
indicator. I decided to take a chance on flying partial panel at a
lower altitude rather than waiting to pass out from lack of oxygen up at
16,000'. Down in the clouds and about 20 minutes later I broke out
between layers. Guess I passed the partial panel IFR test on that
flight.

Center gave me vectors to the McCook Nebraska area where there was a
hole. Here's the first weird thing...about 5 minutes outside of McCook
I reset the alternator breaker (for about the 20th time) and everything
acted normal...normal amps, power, voltage, the works. When I landed at
McCook Nebraska there were cops, fire trucks and the works there. Glad
my wife wasn't with us. Maintenance folks at McCook looked at the
alternator & regulator; all seemed Ok.

Later in the evening the weather was perfect VFR, so I decided to
continue to Iowa where I could spend more time at the in-law's
troubleshooting the system. When I took off from McCook the alternator
was showing 6 amps (normal). Every 10 to 20 minutes the amps dropped by
1, eventually getting to zero. So I shut everything down and flew
pilotage to Iowa.

I talked to the Jasco folks re the alternator & voltage regulator. All
we could find was one wire that was showing a slight drop in voltage
from the regulator to the alternator. Replaced this and thought the
problem was fixed, as all was fine for 5+ hours to/from OSH from Iowa.
However, problem acted up again on way back to Colorado (maybe it's the
altitude <grin>, heat or vibration). Battery is showing that it is
maintaining it's charge, but amps drop from normal ~5 to perhaps 1, 0,
-1, -2 and all around that area. Amps start dropping perhaps 10 min
after takeoff and drop in a linear fashion every 10 or so minutes after
that.

I've downloaded the Jasco wiring diagrams and troubleshooting charts.
Has anyone every heard of a problem like this? Any ideas? The Jasco
folks hadn't heard of a system showing degrading amps like this.

As Paul Harvey says, "Now for the rest of the story." My two teenage
boys, who were with me, and I decided not to tell my wife (at least for
a while anyway). So we got to Iowa, called home and said we had an "Ok"
flight. The next day I'm working on the plane with a buddy of mine in
Iowa and I get a call on my cell phone from a # I didn't recognize. The
person introduces himself as a Delta pilot who was at 37,000' feet the
day before, heard my situation, and spotted the hole that Center
eventually routed me to. I thanked the Delta pilot profusely of course.
He then says, "I'll bet you're wondering how I got your phone number?"
He said he looked up my N # on the web, looked my name with the address
on the web and got my home #. Yep, he told my wife!

Ted
Moose N142SR




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[Ken]

You might want to repost to aeroelectric-list@matronics.com for expert
advise from Bob Knuckolls and the rest of that group. Be prepared for
gentle teasing though in that those guys have published circuits for all
electric panel airplanes that make alternator failures a ho-hum event. I
think you have to join the list first to post to it but it is privately
run by Matt Draille so no SPAM of any kind comes from it. Bob has an
incredible wealth of experience and is very generous with his time.
Ken

Ted Waltman wrote:

I have the Jasco 7555T alternator & J12M24SP voltage regulator in my
Moose with the M-14P engine.

All my flight instruments are electrical (e.g. the Attitude & Turn/Bank
Indicator in particular). Maybe you can see where this story is
going...

Leaving Denver for Iowa 10 days ago (on the way to Oshkosh), I filed IFR
to try to get above a nasty weather system grounding all VFR traffic.
About 30 min after takeoff I broke out above the clouds. All was great,
until I noticed my engine monitor reporting 1, 0, -1 then -2 amps. My
ammeter sensor is on the main current carrying wire out of the
alternator, measuring total amp output from the alternator. Within 5 to
10 minutes I got a "Low Battery" warning. Less than a minute later
(well it seemed like less than a min) everything went South...I lost all
flight & engine instruments.

I got out my handheld radio (sure glad I had it) to get back in contact
with Center. At this point I was also wishing I had my handheld GPS
with me (I left it home thinking, "Who needs it with two panel mount
GPS's in the plane?"). The clouds were rising in front of me; behind me
was solid IFR down to minimums in the Denver area. I talked to Center,
told them I could not, NOT, go into the clouds period. I climbed to 10,
then 11, 12, 14, 15...up to 16,000' trying to stay above the weather.
Center was trying to find me a hole somewhere up ahead to get down
through. Finally I reset the alternator breaker multiple times and at
least got the system running long enough to spin up the turn & bank
indicator. I decided to take a chance on flying partial panel at a
lower altitude rather than waiting to pass out from lack of oxygen up at
16,000'. Down in the clouds and about 20 minutes later I broke out
between layers. Guess I passed the partial panel IFR test on that
flight.

Center gave me vectors to the McCook Nebraska area where there was a
hole. Here's the first weird thing...about 5 minutes outside of McCook
I reset the alternator breaker (for about the 20th time) and everything
acted normal...normal amps, power, voltage, the works. When I landed at
McCook Nebraska there were cops, fire trucks and the works there. Glad
my wife wasn't with us. Maintenance folks at McCook looked at the
alternator & regulator; all seemed Ok.

Later in the evening the weather was perfect VFR, so I decided to
continue to Iowa where I could spend more time at the in-law's
troubleshooting the system. When I took off from McCook the alternator
was showing 6 amps (normal). Every 10 to 20 minutes the amps dropped by
1, eventually getting to zero. So I shut everything down and flew
pilotage to Iowa.

I talked to the Jasco folks re the alternator & voltage regulator. All
we could find was one wire that was showing a slight drop in voltage
from the regulator to the alternator. Replaced this and thought the
problem was fixed, as all was fine for 5+ hours to/from OSH from Iowa.
However, problem acted up again on way back to Colorado (maybe it's the
altitude <grin>, heat or vibration). Battery is showing that it is
maintaining it's charge, but amps drop from normal ~5 to perhaps 1, 0,
-1, -2 and all around that area. Amps start dropping perhaps 10 min
after takeoff and drop in a linear fashion every 10 or so minutes after
that.

I've downloaded the Jasco wiring diagrams and troubleshooting charts.
Has anyone every heard of a problem like this? Any ideas? The Jasco
folks hadn't heard of a system showing degrading amps like this.

As Paul Harvey says, "Now for the rest of the story." My two teenage
boys, who were with me, and I decided not to tell my wife (at least for
a while anyway). So we got to Iowa, called home and said we had an "Ok"
flight. The next day I'm working on the plane with a buddy of mine in
Iowa and I get a call on my cell phone from a # I didn't recognize. The
person introduces himself as a Delta pilot who was at 37,000' feet the
day before, heard my situation, and spotted the hole that Center
eventually routed me to. I thanked the Delta pilot profusely of course.
He then says, "I'll bet you're wondering how I got your phone number?"
He said he looked up my N # on the web, looked my name with the address
on the web and got my home #. Yep, he told my wife!

Ted
Moose N142SR

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[Bill Delcambre]

Wow, just when you thought all that training, skill and a bit of luck
brought you through the danger zone, your wife finds out! Now you've got
problems that no rating will get you through....

If your description of the shunt being sort of 'the first thing out of the
alternator' is correct, I agree with Nigel that you've probably got a bad
diode bridge in the alternator. The reason that alternators don't kill
batteries in cars (no master switch) is that current flow TO the alternator
is blocked by the diodes. If such diodes fail shorted, not only does the
alternator not produce output, but in fact, produces a load on the battery,
which is what you've described. If I were to guess, which is what this is,
you've got a bad bridge that's failing when it gets hot. It WILL fail
completely. You mentioned pulling the alt breaker. If you pulled the
output breaker, it should have eliminated the battery drain. If you pulled
the field breaker, it wouldn't have helped.

If there is any component between the alternator and the shunt, however,
your problem could be with that component and all of the above goes out the
window.

As for the real problem; I'd try flowers and a movie.

Bill


----- Original Message -----
From: "Ted Waltman" <tedwaltman@i1ci.com>
To: <rebel-builders@dcsol.com>
Sent: Wednesday, August 04, 2004 9:55 PM
Subject: Electrical "issues" while IFR (long post)

I have the Jasco 7555T alternator & J12M24SP voltage regulator in my
Moose with the M-14P engine.

All my flight instruments are electrical (e.g. the Attitude & Turn/Bank
Indicator in particular). Maybe you can see where this story is
going...

Leaving Denver for Iowa 10 days ago (on the way to Oshkosh), I filed IFR
to try to get above a nasty weather system grounding all VFR traffic.
About 30 min after takeoff I broke out above the clouds. All was great,
until I noticed my engine monitor reporting 1, 0, -1 then -2 amps. My
ammeter sensor is on the main current carrying wire out of the
alternator, measuring total amp output from the alternator. Within 5 to
10 minutes I got a "Low Battery" warning. Less than a minute later
(well it seemed like less than a min) everything went South...I lost all
flight & engine instruments.

I got out my handheld radio (sure glad I had it) to get back in contact
with Center. At this point I was also wishing I had my handheld GPS
with me (I left it home thinking, "Who needs it with two panel mount
GPS's in the plane?"). The clouds were rising in front of me; behind me
was solid IFR down to minimums in the Denver area. I talked to Center,
told them I could not, NOT, go into the clouds period. I climbed to 10,
then 11, 12, 14, 15...up to 16,000' trying to stay above the weather.
Center was trying to find me a hole somewhere up ahead to get down
through. Finally I reset the alternator breaker multiple times and at
least got the system running long enough to spin up the turn & bank
indicator. I decided to take a chance on flying partial panel at a
lower altitude rather than waiting to pass out from lack of oxygen up at
16,000'. Down in the clouds and about 20 minutes later I broke out
between layers. Guess I passed the partial panel IFR test on that
flight.

Center gave me vectors to the McCook Nebraska area where there was a
hole. Here's the first weird thing...about 5 minutes outside of McCook
I reset the alternator breaker (for about the 20th time) and everything
acted normal...normal amps, power, voltage, the works. When I landed at
McCook Nebraska there were cops, fire trucks and the works there. Glad
my wife wasn't with us. Maintenance folks at McCook looked at the
alternator & regulator; all seemed Ok.

Later in the evening the weather was perfect VFR, so I decided to
continue to Iowa where I could spend more time at the in-law's
troubleshooting the system. When I took off from McCook the alternator
was showing 6 amps (normal). Every 10 to 20 minutes the amps dropped by
1, eventually getting to zero. So I shut everything down and flew
pilotage to Iowa.

I talked to the Jasco folks re the alternator & voltage regulator. All
we could find was one wire that was showing a slight drop in voltage
from the regulator to the alternator. Replaced this and thought the
problem was fixed, as all was fine for 5+ hours to/from OSH from Iowa.
However, problem acted up again on way back to Colorado (maybe it's the
altitude <grin>, heat or vibration). Battery is showing that it is
maintaining it's charge, but amps drop from normal ~5 to perhaps 1, 0,
-1, -2 and all around that area. Amps start dropping perhaps 10 min
after takeoff and drop in a linear fashion every 10 or so minutes after
that.

I've downloaded the Jasco wiring diagrams and troubleshooting charts.
Has anyone every heard of a problem like this? Any ideas? The Jasco
folks hadn't heard of a system showing degrading amps like this.

As Paul Harvey says, "Now for the rest of the story." My two teenage
boys, who were with me, and I decided not to tell my wife (at least for
a while anyway). So we got to Iowa, called home and said we had an "Ok"
flight. The next day I'm working on the plane with a buddy of mine in
Iowa and I get a call on my cell phone from a # I didn't recognize. The
person introduces himself as a Delta pilot who was at 37,000' feet the
day before, heard my situation, and spotted the hole that Center
eventually routed me to. I thanked the Delta pilot profusely of course.
He then says, "I'll bet you're wondering how I got your phone number?"
He said he looked up my N # on the web, looked my name with the address
on the web and got my home #. Yep, he told my wife!

Ted
Moose N142SR




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[Alan Hepburn]

Curious that you got -ve amps. That should be impossible unless you have a
defective diode in the alternator. Did it still show negative with the
alternator main breaker pulled?

If you're flying an all-electric airplane IFR, you should at least have an
emergency bus fed via a diode and powered by a separate battery. Trouble
is, those gyros are going to suck it dry pretty soon. A better idea is a
second alternator. You can get a little one that fits on the vacuum pump
pad and puts out 8 amps, which is good for a fair bit of emergency power. I
have an Grand Rapids EFIS for my Elite, which uses very little power. As a
backup wing leveler, I plan to use the Tru-Track turn
co-ordinator/autopilot, which will keep the wings level in cloud and do
something useful at other times. By the way, don't run any kind of master
solenoid off your emergency power source - they draw about 3 amps.

My partner and I had a related experience in a Twin Comanche. He enetered
cloud pointing straight at Boston Logan at 400', and promply had a total
electrical failure. He flew the prescribed triangles for a while, but no
interceptor appeared, so he headed north west where he knew the WX was
better and turned on his ELT. He climbed and eventullay got on top, the had
to keep climbing to stay that way. Like you, he wound up at 16,000, where
he began to get hypoxic. By this time he figured he was past the mountains,
so he started letting down. At 7,000, the lights came on, and he was able
to land at Massena. Checked everything and it appeared normal, so he
continued VFR to Ottawa. With two alternators, we looked for a common
cause, and changed the master solenoid, and put warning lights on the
starters to confirm they weren't energised (now there's a though for you!).
Nothing found. Three months later, I'm IFR from Winnipeg to Calgary, and
again have a total electrical. I am VMC at the time, so just pull out the
handheld and cancel IFR. After this, I had both alternators overhauled, and
haven't seen the problem again in 10 years!

Regards, Al




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[N.Smith]

Hi Ted

This was returned from your private address

Nig


Hi Ted

You got it. The diodes convert the AC produced by the alternator into DC.
They also prevent reverse current flow into the alternator.

The regulator senses the voltage on the battery/bus end, and opens the
throttle on the alternator to increase the supply to compensate if it see's
a low battery/bus volts.

A working regulator can throttle right back the alternator when the battery
has been fully charged, but it will still be producing a supply to run all
your services once the battery is fully charged.

A reverse current is a fault, and probably the diodes in the alternator are
the most likely culprits (this would also account for the gradual reduction
in charge to discharge. A semiconductor that is being affected by heat will
often change it's characteristics slowly (a diode is a kind of
semiconductor), although an internal fault in a regulator could still with
some designs cause a similar effect. Without knowing exactly what's inside
your alternator and regulator I can't say for sure.

Once you're happy with your wiring in this area, It's probably easier the
change the alt (or reg) and see if that cures the fault.

Nig




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