[V8] Charging Problem
Michael Larosa Jr
Mc.Larosa at Sun.COM
Wed Nov 17 08:49:40 EST 2004
looks like a job for the alternator post :)
Tony and Lillie wrote:
> Subject: [V8] Charging Problem
>>I just replaced a dead battery in the V8 but still get a battery warning
>>indicator in the information display. I measured the voltage at the
>>under the hood and it was 11.5V. I think it should be around 14V if the
>>alternator is working properly. I cannot even see the alternator. Can it
>>rebuilt? Are rebuilts available? More importantly, does my diagnosis sound
>>Also, could the low voltage cause funky symptoms like high idle rpm and
>>hunting at around 1500 rpm? There were a couple of very expensive sensors
>>that were replaced that took care of similar problems not too many km ago
>>I would hope those would not be acting up again.
> Several things you can do to check it. First, check the voltage at the
> battery. If it is lower than 12.8 with the car running around 1500, more
> than likely it is a bad alternator. The alternator is on the bottom of the
> engine on the passenger side. You have to remove the underside tray, the
> cover on the back of the alternator, and then the exhaust shield on that
> side. Then IIRC there are two bolts holding it on. Before you pull it,
> though, I'd also check voltage at the back of the alternator with the car
> running. There is also a way to check the voltage in the climate control
> sys, but it's not always accurate. I'll send it to you if you are
> And, yes, it can cause all kinds of funky problems.
> Tony Hoffman
> Audifans V8 mailing list
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_/_/_/ _/ _/ _/ _/ Mike LaRosa
_/ _/ _/ _/_/ _/ TSE - HAS
_/_/_/ _/ _/ _/ _/ _/ 1617 Southwood Drive
_/ _/ _/ _/ _/_/ Nashua, NH 03063
_/_/_/ _/_/_/ _/ _/
S U N Phone: 781/442-1250
S E R V I C E S Fax: 781/442-5488
Email:mc.larosa at sun.com
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Here is a little thing I wrote up a few years
ago for a nasty issue on a 89 100 Avant....
Hope it helps!!!
"Troubleshooting and Correcting the dreaded
12.5 at the Battery - 13.7 at the Alternator"
Some Potential Symptoms:
A) Car starts and runs fine, The dash gage measures a little low, but
there aren't any numbers on the voltage gage, so you don't really
notice it's been slowly sitting more and more to the left.....
B) Every time you run the A/C for an extended time the car won't turn
over the next time you stop and try to start it again.......
C) Battery dies for no apparent reason, you jump start it and leave all
electricals off, because you wan't the battery to charge back up...
you go to your friendly mechanic... and what does he/she do ? pops the
hood (Not the back seat) and measures the voltage at the jump start post
(Which is a direct connect to the alternator) and low and behold the
output is 13.7..... they announce looks ok to me, maybe you need a new
battery ? ) $50.- to $100.- bucks (New Battery) and a week later, it
does it again!!! Doooooohhhhhhhhh!!!!
Ok, The reason the A/C kills the battery in this instance is when you
turn on the A/C it turns the electric radiator fan onto hurricane mode
and it sucks huge amounts of juice from the battery. As it is when
the electrical system is working properly it barely keeps up to the
current draw. With the battery barely getting any charge from the alternator
the battery dies fairly quickly.
Next Ok, Why does the jump start post measure 13.7 and the battery 12.5 ?
because the wiring harness for the charging system goes like so:
Alternator LUG--Cable-- Jump start Post
*** Pressed Clamp (Your problem area)
|------- link to dash cluster gage
The "Pressed Clamp" is a metal tube about 3-4" long in which the battery
cable is inserted into one end and the alternator cable inserted into
the other. Then's it's pressed together to form a connection.
Inside the clamp it get's corroded with the green goo just like your
battery post's used to when you owned cars where the battery was under
the hood :-)
Vehicles that can be affected: 5000/100/200 (likely the V8 as well...)
Multimeter w/point attachment (Digital preferred)
Wrench to disconnect battery
Seriously heavy duty wire cutters to cut battery cable
(4) Chrome hose clamps - (3/8" wide) x 1.5dia" or so
(with hex head preffered)
Nut Driver w/socket that fits above hose clamps
Grease or Lithium grease in a spray can will do
4" x 4" piece of 1/16" thick rubber - I used old motorcycle tube
A Printout of these instructions when you start(Seriously)
(You'll be taking notes.....)
Sharp Carpenters Knife or New Razor Blades.....something good
enough to cut the plastic of the battery cable.
Plastic Electrical tape
Cold Beer - (Optional)
Everything else but the Beer is a must, I would read the procedure
to get an understanding of what's involved and why you want all this
stuff before you start.
This way, If you don't have some of the tools, you may be able to
come up with some suitable substitutes in advance.
Background.... I've been through this on my wife's 89 100 Avant 125k miles,
after 2 voltage regulators(1 cheapy $25.-, and a $50.- Bosch), 1 Alternator
belt, and 2 alternators... (Don't get one from PEP Boy's, mine lasted
1 day then died.) and a tremendous amount of cursing.... I decided to
devote a day to getting to the bottom of this debacle myself.
_____________________ These spots are for you to write down
your findings as we explore the problem.
- Take out the back seat.
- Open the hood.
- Front of car on ramps helps, but is not required. Remember to block
tires and use emergency brake, unless of course you have bad emergency
brake levers on your rear calipers, then DON'T grab the emergency brake,
just block the tires :-)
1) Measure battery with the car OFF ______________
Your Target is (12.8 +/- .1)
-If it's below target, it's not being charged sufficiently or
the battery is on the way out. How far along is the battery
in it's projected life span ?
(Believe it or not I had Sears check the battery with a Bear machine
of some sort that put a load on it, looked ok, then they charged it
and gave me a loaner battery for a few day's... whilst mine sat around
for a few day's to see if it discharged. It didn't, battery was ok)
2) Measure at Jump start post with car OFF ____________________.
Your Target (12.8 +/- .2)
-If battery measures 12.8 and jump start post is at 12.5 or
less your losing voltage from a bad connection in the
cable somewhere.... Keep Reading...
START YOUR ENGINES!!!!, Imagine checkered flag waving... sorry, getting
3) Grab the multimeter with a pin point end. Measure voltage at the
jump start post with car RUNNING ___________________.
Your Target (13.7 +/- .2)
-If voltage fluctuates wildly, as in more than .5 volts, possible
regulator. $25.- (Cheap..) to $50.- (Bosch)
-If voltage less than 13.7, I'd bring it somewhere reputable and have
the alternator tested. It should put out an easy 13.7, could be as
easy as new brushes.
-KEEP READING, you may have more problems.... let's get 'em all
checked out while where here.
4) Measure at Battery with car RUNNING ______________.
Your Target (13.7 +/- .2)
-If 3) meets target, but you fail here with less than 13.5,
SHUT THE CAR OFF.
How'd you do ? you probably failed somewhere or you wouldn't be
doing this on a sat/sun instead of watching the ball game with
a frosty beer in hand... :-)
OK, If you failed and got the dreaded 13.7 Alt - 12.5 Bat, again...
The Fun Part...
Follow the Positive cable from the alternator, it travels across
the top of the passenger side frame rail into the firewall at the
passenger side foot well.
Pull up the carpet on the passenger foot well.
On the top of the foot well on the right side, you'll see the
cable coming through.
Start up the car and poke that positive side pointy end on the
Multimeter through the cable to check the positive voltage. Check it
before and after the "Pressed Clamp". The "Pressed Clamp" Looks like
a 3 - 4" long by maybe .5" thick shrink wrap section on the cable.
On the wife's car it measured 13.7 on the alternator side and 12.5
on the battery side.....
If this is what you get, go grab a frosty out of the fridge, you've
just figured out the problem :-)
Whilst drinking said Beer, you get to decide do I go out and buy a
new cable from Audi for $430.- bucks or do we fix this puppy
right know with all the Tools/Supplies outlined above ?
I vote we get it over with and continue.
- First things first, DISCONNECT THE BATTERY!!!!!!!!!!!
- Back to the passenger footwell... pull on the cable and see if
there is any slack.
- Your gonna need about 3-4 inches.
- If NOT, there is a clamp near the alternator where the cable is
bolted in. Unbolt it from there and you'll get the slack.
Back in the car at the passenger foot well....
- Once you have the slack, get the Big wire cutters and cut out the
Dreaded "Pressed Clamp". Making sure to cut as close to the clamp
as you can.
- Strip approx 2" of insulation from both sides.
- Put the 2 Chrome clamps on each cable loosely.
- Put the 2 cables side by side so that the bare ends both touch
each other's plastic sheathing. I'd try to make an ASCII drawing
but the picture would be more confusing than helpful......
Feel free to give me a buzz and I'll fax a drawing.....
978-442-1250 Work Number.....
- Here is where we'll need the Nut Driver and the Vise Grips, Line up the
Chrome clamps on the exposed cable a 1/4 inch or so from the ends.
So that there is a 1/4 inch of cable showing between the clamp and
the plastic sheathing. Hopefully this makes sense...
- Use the Vise Grip to hold the clamp in place, this will also give you
some leverage when your tightening it with the Nut Driver.
- When it's tight. Put the Rubber section over the area and loosely clamp
Here's where we get to start the car up and re-measure with the
multimeter :-) Just make sure the cable is not exposed anywhere!!!
Don't forget to hook up the battery.....
I'm going to assume success......
- Ok, NOW DISCONNECT THE BATTERY!
- Take the rubber off the cable.
- I put a piece of cardboard behind the working area of the cable and
sprayed it heavily with Lithium Grease. It's all I had at the time.
- I think a good heavy hand applied grease might work better here, glop
it on thick. This will hopefully slow down the corrosion enough that
next time it happens, you won't own the car :-)
Where in the home stretch......
- Put the rubber section back over the cable and make sure it's big
enough to cover the whole thing and then some. Secure it with the
other 2 cable clamps.
- Wrap nice and tight and completely with Plastic Electrical tape, This
will help keep out any moisture as well as keep it all in a nice bundle :-)
RECONNECT BATTERY AND TRY IT AGAIN.
- Wouldn't want to put everything back together and find we missed
- Everything working ok ? Yes, Excellent, put it all back together,
sit back have a couple more beers!!!
Hopefully my anguish over this will help somebody else save some time, money
and frustration. I know other people on the list over the years have
saved me lot's of both :-)
_/_/_/ _/ _/ _/ _/ Mike LaRosa
_/ _/ _/ _/_/ _/ TSE - AMER SCC
_/_/_/ _/ _/ _/ _/ _/ 1 Network Drive
_/ _/ _/ _/ _/_/ Burlington, MA 01803
_/_/_/ _/_/_/ _/ _/
E N T E R P R I S E Phone: 781/442-1250
S E R V I C E S Fax: 781/442-1418
SCC PHone: 781-442-1945
Email: ml75198 at east.sun.com
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