Author Topic: Voltage problem .. still  (Read 11187 times)

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Offline rkellerjr

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Voltage problem .. still
« Reply #15 on: January 20, 2007, 06:03:36 PM »
By the way, your new avatar is somewhat disturbing  :shock:
Rich

Offline Joker (告r茺agon)

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Voltage problem .. still
« Reply #16 on: January 20, 2007, 06:15:06 PM »
Quote from: "rkellerjr"
By the way, your new avatar is somewhat disturbing  :shock:


Larry


Offline ta78w72

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« Reply #17 on: January 20, 2007, 06:41:58 PM »
My car was grounded to the pump too.  However, I moved it to the correct ground point which is directly to the head just to the left of the number one spark plug.....that's for a 1978 Pontiac 400.

Offline Rick

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« Reply #18 on: January 20, 2007, 08:24:27 PM »
Rich -- do you have an electrical schematic of the engine?  If not, I've got one in photobucket I can post.  It really helps to "see" where these things go, especially if your wiring has been hacked.

And Larry is right -- the ground connections make the "return" path for the current coming out of the battery and off the alternator, so they have to be as good (preferrably better) than the +12 VDC connections going out.

Let me know if you want me to post it.

Offline Amtrak

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Voltage problem .. still
« Reply #19 on: January 20, 2007, 10:02:37 PM »
Some times the main electrical harness where it plugs into the back of the fuse box gets coroded where the copper terminals meet each other. you said you tied on to the brown and red wires  that go to the starter solenoid and alternator but the problem would be between your splice and the ignition switch where the alternator field wire signal comes from.. So to test my theory we must run jumper wire from the alt wire spade on the ignition swith on top of the steering column to the alt field turn on the voltage regulator terminal on the alternator wich should turn on the voltage regulator and cause field excitation and stator  generated current flow to the battery which should bring the battery voltage to 13.8 volts as indicated by the dash volt meter or voltagemultimeter checking directly across the battery.  However; If I am wrong the car will burst into flames and Explode so use extream caution...

Offline milly

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« Reply #20 on: January 20, 2007, 10:06:48 PM »
Rich I have both of my batteries negative cables running to the cylinder heads. I ground off a bare spot free of paint and surface rust at a bolt hole then bolted them to the heads. Seems to work out pretty good. Another thing to try might be running a good wire from the alt. output post to the positive battery terminal. I looked in my photobucket and I don't have a good pic of the charging system or wiring. If you need it let me know and I'll brave the cold to take a few pics.  :D
John
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Offline Eagle 1

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Voltage problem .. still
« Reply #21 on: January 20, 2007, 11:02:12 PM »
Rich, first lets talk about your problem.  You say the alternator will charge at 13.5 volts after the engine warms up?  What about when you first start the car what does it charge?  
My car does a similiar thing.  It wont actually start charging until you bring it above idle and then it will "kick in" and start charging.  From then on its ok.  I personally dont think there is a problem with this.

 I am going to post a picture of my engine.  If you look closely you can see where my ground wire (black wire) connects to the engine head.  It is towards the front of the head, forward of the temp. sending unit, on one of the head bolts.  This is where you need to hook the ground coming from the battery.  Now, there is also a ground located on the back of the engine, near the distributor, that goes from the back of the engine block to the firewall.  This grounds the engine to the body.   Make sure both of these grounds are clean and are making a good connection.


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Offline Joker (告r茺agon)

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Voltage problem .. still
« Reply #22 on: January 21, 2007, 11:16:02 AM »
Quote from: "Eagle 1"
Rich, first lets talk about your problem.  You say the alternator will charge at 13.5 volts after the engine warms up?  What about when you first start the car what does it charge?  
My car does a similiar thing.  It wont actually start charging until you bring it above idle and then it will "kick in" and start charging.  From then on its ok.  I personally dont think there is a problem with this.


This is what AmTrak and I were also referring to about the brown wire from the ignition switch energizing or exciting the field coil. If that doesn't happen raising the idle slightly does it.
Larry


Offline jjr

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« Reply #23 on: January 21, 2007, 12:28:38 PM »
Here's my 2 cents worth...


 1) It is critical that the engine AND body have a path to
    the negative side of the battery. Quite literally the
    metal of the engine and body IS part of the circuit.

    Think about it, one battery lead (+) to the distributor?

    The spark plugs couldn't spark unless they were grounded
    into the block.

    Often we tell folks that their dash lights/gauges need a
    good ground to work. The engine needs the ground straps to
    the body.

    It's not important electrically "where" the battery cable
    bolts to the engine.  

 2) Two things about alternators...

    A) They don't work unless a 12v source feeds the field. Less
       than 12 less than advertised output. (I'm simplifying a lot)

    B) Auto Parts places don't test re man units quite as well
       as you'd think. Intermittent or marginal units may escape
       their "testing"

 3) Engine harness, is this thing hacked up? could there be any
    shorts to ground? Bad connections?

 Summary

    Maybe you have a weak "new" alternator, maybe the strain of starting
   pulls down the battery enough to effect the voltage applied to the
   alternator field. The diminished output (from low field voltage)
   eventually bumps the battery up high enough to properly stimulate
   the field and it's output comes up to specs.
    Maybe you have a short/drain to ground pulling down the battery
   voltage down until the alternator output can finally overcome it's
   load. Have you tested for parasite loads?
     
   Joe
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Offline rkellerjr

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« Reply #24 on: January 21, 2007, 03:28:41 PM »
Wow, looks like I've got a lot more to look into.  

I was taking my dash apart and noticed wires coming in through the firewall behind the kick plate.  That is not good.  Closer inspection reveals that at least one of these wires may be the main power coming from the alternator into the cab.  If so, I need to double check, then it looks like they may have bypassed the engine harness layout.  If this is the case I'll need to rethink this whole situation and by an engine harness and re-wire ... again.  I may also by a dash wiring harness to make sure I have a good fuse box in the car.  This is daunting to me to say the least but, it can't be helped if this is the issue.  Or at least if this is hacked in this way, I won't feel safe unless I re-wire the these two components of the wiring system.

Thanks guys for the input, I now have a source if information to come back to.  I'll keep ya posted as to my progress.  I'm starting to believe it's the exciter wire that may be the problem and not the ground but, I need to look into how much the wiring "might" be hacked as it comes into the car.  As I said previously, the exciter wire was actually tied into the main power wire coming from the alternator under the hood.  

Anyway, wish me luck!
Rich

Offline Joker (告r茺agon)

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« Reply #25 on: January 21, 2007, 04:10:36 PM »
Quote from: "rkellerjr"
Thanks guys for the input, I now have a source if information to come back to.


That's assuming Rick and Milly don't succeed in crashing the forum like they did TAC. :lol:


Larry--->Who just can't let it go.
Larry


Offline milly

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« Reply #26 on: January 21, 2007, 04:12:52 PM »
I did not have anything to do with Rick crashing TAC. That's Ricks baby.  :twisted:


I can tease him for now. He is going to watch the Patriots beat the Colts in the AFC title game tonight.  :wink:  :P
John
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Offline rkellerjr

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Voltage problem .. still
« Reply #27 on: January 21, 2007, 04:30:34 PM »
And you can get ahead of him in posts while he's watching the Colts!
Rich

Offline milly

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« Reply #28 on: January 21, 2007, 04:47:02 PM »
Heck Rich, I can make up some time on him AND watch both of todays football games.  :D
John
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Offline Tin Indians Rule

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Voltage problem .. still
« Reply #29 on: January 21, 2007, 09:09:41 PM »
Quote from: "SirLDragon"
Oops. I means ground from the batt. :oops: Meaning the neg. batt cable.
Where does it go/attach?

Actually the brown wire is the "trigger" wire which energizes the alt. field to start the charging. Without it the field won't energize until the engine is revved off idle.


Larry, My first 76 TA did something very similiar. When you cranked the car the volt gauge would only show about 11 volts no matter how long it sat there and ran. Even if you drove it the gauge stayed around 11 volts. But if you revved the motor to 2500 RPM's or more the volt gauge would jump immediately over to about 14 volts and stay there until you turned the car off and then same thing over everytime.
Are you saying that's normal?
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