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  1. #1
    CICERO FAN CLUB MEMBER prefect's Avatar
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    Default Any auto sparkies out there please?

    Took bus to work as it was a bit dark noticed alt light was on very dimly as motor was revved it gets slightly brighter. Checked its output, nothing just battery voltage 12.7VDC. Now the thing I have not struck before is the alt light is dim when the key is turned on motor not running.
    Checked voltage at the light terminal on the alternator and its battery voltage with key turned on. If this wire is touched to earth the alt light is bright. The alternator has only two connections battery and the light. The light wire is 12v from the key thru a lamp and the earth wire goes to this connection. Could it be the diodes rectifier/voltage regulator? Its an extreme goat f**** to get alternator out so I only want to do it once.
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  2. #2
    Retired old codger kenj's Avatar
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    Default Re: Any auto sparkies out there please?

    Can't really help but I wondered if the system was made by Lucas, the Prince of Darkness?

    Ken

  3. #3
    CICERO FAN CLUB MEMBER prefect's Avatar
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    Default Re: Any auto sparkies out there please?

    Nippon Denso from a Ford Trader one of my employees rolled in Woodhill Forest. Good chance the warning light holder is Lucas though
    Its amazing how Potatoes give us chips,fries and Vodka.

    Get your s*** together every other vegetable.

  4. #4
    pcsourcepoint
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    Default Re: Any auto sparkies out there please?

    So you have done DC test getting 12V. rev to about 200 rpm - if no increase then possibly regulator. I also do voltage drop tests on both positive (output) and negative (earth) side using MM. Should be be 0.2 to 0.5 V or less. Also do AC voltage output test - should be less than 0.5 V or so. If higher then diode(s) maybe open in the rectifier pack.
    Last edited by kahawai chaser; 25-11-2018 at 01:29 PM.
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  5. #5
    Smiling Down On Youse SurferJoe46's Avatar
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    Default Re: Any auto sparkies out there please?

    I DO NOT THINK IT'S BEEN SUGGESTED OR EVEN ALLUDED TO

    ----> BUT NEVER --- EVER --- CROSS YOUR HEART AND HOPE TO DIE ----

    DO NOT DISCONNECT THE BATTERY CABLES FROM THE BATTERY WHILST THE ENGINE IS RUNNING OR THE KEY IS IN THE 'ON' POSITION.

    JUST DON'T!


    Using a DVM, take the DC Voltage output reading on the lug where the output wire attaches on the alternator with the engine OFF, writing it down. Then read it again when you start the engine. Write this down too.

    Now - read the AC Voltage at that same alternator post with the engine running.

    If that last AC voltage reads over 0.013 ACV.... it has a shorted diode.

    This AC test on the DC Output lug is to find if the alternator is sending AC voltage into the DC circuit. That's a bad thing as it will damage the battery and possibly the electronic devices in your vehicle.

    BATTERIES HATE AC CURRENT! (this will be on the test at the end)

    If you test on that same output lug with the meter on DC Volts, at idle, the voltage must not be at or near the battery voltage when the engine is OFF.

    Check what you wrote down for those DC values and compare them.

    Alternators are installed to "carry the battery draw" at idle and keep it from discharging the battery. Period.

    Vehicle GENERATORS COULD NOT DO THIS WELL and they were always 'falling behind' in making sufficient voltage to keep the battery fully charged at idle. It was evolutionary. Sorry.

    If your charging system could NOT stay ahead of the cumulative system's current draw, then your headlamps will 'flare' when you start to move after a stop light. We don't want that to happen. It makes the vehicle look cheap.


    FWIW:
    this is where the alternator is king for creating current to stay ahead of the battery while the engine is idling and the load of lights, AC, wipers and heater blower is factored in.

    The alternator will produce voltage sufficient to stay ahead of the battery drain.

    Any higher RPM of the engine - and by extension, the alternator - will allow it to create a higher charging rate as you drive away --- or are cruising on the highway. Either way - the alternator is designed to NOT lose voltage at idle.


    What's wrong in the alternator if it isn't charging well or correctly?

    1. The DIODE TRIO --- or whatever sampling diodes the system uses --- to establish a floor-level voltage reference point may be defective or damaged. This diode trio or sampling system is used to control the saturation of the electromagnets that the stator cuts through, creating a flow of electricity. It is not the Voltage Regulator.
    2. One or more (usually just one though) of the CHARGING DIODES is either blown OPEN or shorted CLOSED. Either condition is a 50:50 proposition - BUT there will be more about this in a bit..... hang on!


    Let's see if I can find a drawing of what the diodes do...... this is gonna be tricky!

    Click image for larger version. 

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    The ORANGE CIRCLE AND ARROW indicate the diodes including the diode trio.

    The three diodes on the top and the three on the bottom are rectifier diodes. They get hot and need some serious cooling as they allow alternating current to ONLY FLOW in one direction - depending upon which way the output from any of the three LOBES is generating current flow.

    The other three DIODES are called the DIODE TRIO and they just sample the output of the individual lobes to send a signal to the VOLTAGE REGULATOR and to signify (by conducting voltage to the idiot light) if there's a problem with the alternator or not.

    REMEMBER ---> true to it's name, an ALTERNATOR creates ALTERNATING CURRENT---> which the battery cannot tolerate at all, if not very much.
    The electronics - computers, stereo/CD player, etc cannot tolerate AC either.
    Lights don't care unless they are LEDs --- but then it's just a polarity-thing.
    For simplification, we won't bother differentiating one lobe from another (there are three), as it might pertain to labels (A, B, C, f'rinstance) and we'll just concern ourselves with one lobe at the point: called ---> A LOBE.

    Following just ONE LOBE as it rotates through the magnetic field - suppose we start where the electrons start to flow as a POSITIVE current, and this will be allowed through one of the two diodes on the A LOBE.

    Click image for larger version. 

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    As the lobe continues rotating, it goes to the top of it's travel relative to the electromagnets, and then the current reverses itself and the first diode ceases to be needed. The other diode on that lobe now comes into use as the current begins to flow the opposite direction.

    Then the second diode is allowing electricity to flow through it and this is gathered into (either) the BATTERY - NEGATIVE (ground) or the BATTERY + TERMINAL.



    Diodes look like this: |< or >| (sorry for the non-graphics here) - but electricity can ONLY FLOW IN ONE DIRECTION through a diode, or being blocked and it cannot allow any current to flow backwards.

    Here's the direction that electricity flows through a diode: from this way ---- >| -------- to this way

    Reviewing here ---> if a diode is SHORTED, it will allow uncontrolled current to flow in both directions, but since it is only one of six, it will just show as a warning lamp glowing and AC on the DC side of the alternator output.
    DC output will also be somewhat lower - but the tip here is that 0.013+ AC Voltage on the DC side of the alternator output lug.

    IF the diode is blown OPEN, it will not flow electricity in either direction. You will notice this problem as a significantly lower voltage output at idle, and if you have a scope, it will show a sharp rise in voltage as it cannot jump over the open diode.

    BOTTOM LINE --- if you cannot change the diodes or the diode trio yourself, then replace the alternator.


    "Life" is what happens to you while you're busy making other plans


  6. #6
    CICERO FAN CLUB MEMBER prefect's Avatar
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    Default Re: Any auto sparkies out there please?

    Probably was diodes but when I pulled it apart the housing was buggered where the bearing had spun in it. Neigbs gave me one he had loafing thinks it was from Bighorn diesel. Threw it on had to change the pulley to suit bigger B section belt. Has to run two xtra wires one to battery for S connection and another one I to the key. Gone from a two wire system to a 4 wire one. Had to modify mounting, adjustment arm, vacuum pump oil feed and drain. Run up sweet and all for free.
    Thanks for replies.
    Its amazing how Potatoes give us chips,fries and Vodka.

    Get your s*** together every other vegetable.

  7. #7
    pcsourcepoint
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    Default Re: Any auto sparkies out there please?

    Good vid here from Daves Farm which includes schematics, and essentially 3 coils, hence the need for 3 sets of diodes. A ripple circuit is formed, I think from the 3X AC circuits which are out of phase to each other. thus smoothing out to DC via diodes is generated. Some cars like my Honda has a ELD load detector module to limit the output of the alternator to optimum output, so as to reduce load on engine - and supposedly to reduce fuel consumption.
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  8. #8
    Smiling Down On Youse SurferJoe46's Avatar
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    Default Re: Any auto sparkies out there please?

    Your Honda-guy rather semi-eloquently says some very incorrect things:

    "The ELD is essentially a current transformer that monitors the amount of current draw the car is pulling from the battery.
    "Transformer" is a rather antique and crude analysis of the device.

    Besides, it doesn't care about CURRENT anyway! It's part of the VOLTAGE REGULATION system.

    Period.


    "This amount varies from time to time depending on what you have turned on (various electrical devices).
    This is the normal job of the ECM and it sends out a digital signal to the field to make it more 'magnetic' so the stator works in a much more saturated magnetic environment - making more 'electricity' for the accessories and battery.

    BUT - the ECM does not decide this for itself.

    There is a device that informs the ECM to start producing a digital signal to excite the alternator through the Quad Drivers --- or their equivalent in other makes/models of vehicles --- at idle or when the actual three-lobed diode trio signal is less than 600 Hz.

    That would be 200 RPM at the alternator - that is the usual threshold for the time it is to be involved in artificially exciting the alternator to produce electrical amplification.

    PS: alternators do NOT 'make' electricity. They are only capable of amplifying it.


    The ELD will vary the output between .1 to 4.8 volts to the ECU
    . Yes - this is true.
    The maximum floor-voltage the ECM ever 'sees' is 5.0VDC, and this is within reasonable variances.


    This reference voltage is what tells the ECU to increase or decrease the field strength in the alternator.
    Well --- sortta. Voltage regulation to the ECM is controlled by one of the four Quad Drivers as driven by the ELD .... but we'll skip over that for another time.....

    Even though the voltage level is still very important in today’s cars, the amperage draw throughout the different systems is monitored to a greater degree than in years past.
    This would be pretty close to true if only he hadn't said that this is all about amperage.

    However shortsighted that statement he made may be - there's some truth in it as there have been somewhat less than quantum changes in the systems since the advent of digital controls and signals.

    This is why the use of Digital-Excitation is in vogue.
    It works too.

    That said: Voltage is the single most important value to be regulated, assuming the battery is decent and there's no high resistance in the circuit.---- although any high resistance in the circuit would smoke too - making it fairly easy to find.


    As the current is ramped up or down the ELD ratchets the output voltage to the PCM to compensate for the load.
    Again - --- Sorta correct.

    He's assuming that the ECM uses a voltage signal to engage the ELD or not. This is not totally true nor totally incorrect.

    Still in use is the old 'Voltage Regulator' that has ultimate control over the charging rate since it has the ability to 'see' the voltage available at the battery and then compare it to the capability of the alternator at any moment in operation. The values it 'sees' are known - in and by it's design to be able to amplify at it's intended values. That's all. No big mystery!

    Batteries are storehouses for CURRENT, although for clarification, I guess I could say they are storehouses of Wattage, since it all boils down to Volts x Amps.

    This is in consideration for VOLTAGE and AMPS, tied into the capacity of both the battery and the maximum capacity for the alternator to amplify the voltage to recharge the battery or keep the lights from flickering.



    Take the headlight flickering condition. This is usually associated with low idle/near idle conditions.
    This is pretty much OK - but rather short-sighted since there are other 'things' involved here.

    This is where the ELD has detected a lower need for any alternator output increase so the headlights are running primarily off the battery.
    Uh - that's really a confusing statement that I'd like to de-fog for youse guys ---> and it's not totally so!

    Once the voltage regulator 'sees' that the output of the alternator is approaching or has exceeded the capacity of the battery ---> because the battery is being drawn down below threshold - it'll call out to the ECM-tac-ELD circuit to convert the field excitation from a DC voltage to a digital voltage/signal of 600Hz to artificially make the alternator put out!


    As the current is increasing the ELD starts to send the corresponding signal to the PCM which will then increase the field signal to the alternator, however, if the vehicle isn’t under any additional load the ELD will also sense this and decrease the need for alternator output.
    This is rather circuitous thinking - OF COURSE if the battery is going south (toward a discharge) then the ELD will know it because the voltage regulator tells it so!

    The ECM interprets this message and then the alternator changes it's field current from a weakened DC one from the battery reference voltage, to a stronger Digital signal that can artificially induce more output of the alternator!

    The ELD then, through the Quad Driver CAN (read that with emphasis) CAN excite the alternator into producing more current. That's it's job.... but not the way he states it.


    At that near idle condition the ELD is working overtime (HUH? On what timetable do any electronics work?) observing the current draw (NO it does NOT 'observe any current draw" in- and or of- it's own observational ability) because of the headlights, thus, the flicker… on and off, and on and off. (In some cases this is considered “normal operating conditions”)… yea right… explain that to “Mr./Mrs. Customer”… (Good luck with that one.)
    OK - there's where he really steps in #2!.
    Headlamp 'flicker' has always been associated with (either) LOW battery voltage - or - poor alternator or generator output - or - idle speed too low.
    IF the battery has limited capacity to hold-receive-distribute current, then the lights are going to flicker unless the regulator can somehow MAKE the alternator rise above the situation.
    Howszat?
    If the battery cannot do anything with the charge coming from the alternator, and it can only achieve less than 13.2 - 13.7 Volts in it, then it needs to be replaced.

    At this point, we should re-visit the bad diode part of my book I've written here - but suffice to say that if the alternator has a bad diode, the charge rate and floor voltage will be significantly reduced or even worse, the AC ripple on the DC side can kill any one or more sensors to regulate this system too.

    There's that to consider.

    HOWEVER - that said ---> the alternator will try it's damned-est to charge a bad battery - resulting in premature death or damage to itself (think: diodes. wires in the stator, field, etc) and resultant smoke escaping.
    NO lamp flickering is considered 'normal operating conditions' to anyone who knows better.


    <yadda, yadda - clippity, clip>

    There is something else to think about when you’re dealing with a customer’s Honda with a battery charging issue.
    He totally denies that there is a battery at possible fault here - don't he?

    DO a battery capacity test first to eliminate it as the culprit. Surging or flickering headlights is almost always a battery problem.


    Since aftermarket “add-ons” are usually attached to the positive terminal of the battery, their current path is not flowing through the ELD.
    WRONG WRONG WRONG WRONG WRONG!

    The only 'current' going through this ELD is - for all intents - just a reference voltage to tell the ECM to turn UP the charge rate by exciting the fields a little stronger, or to turn ON the digital excitation system.... because in that last part, the ECM also 'sees' that the engine is idling (Tach+CMP+MAF/BMAP/MAP+CKP+ISC values are all telling the ECM so!)

    'Current' at the ELD is in NO WAY capable of 'telling' the ECM to increase the voltage to the field by sampling anything by and of it's own ability other than the external sensors that are designed to monitor the voltage of the system.


    Things like the amplifiers, LCD monitors, and anything else that isn't fed through the factory wiring is drawing an additional current level that isn’t being monitored. Since the ELD isn't detecting any additional current draw from the battery, it is going to keep the alternator's output at the minimum level under the conditions it is designed for. (12.3 volts - just enough to keep the battery charged, plus enough to run the systems of the car.)
    More WRONG WRONG WRONG WRONG WRONG! HERE!

    AND where in h - e - double hockey sticks is it written that 12.3 Volts is the correct battery static voltage? It's actually 13.2 at 78F.

    Add-on electrical devices can certainly cause some grief to the battery-cum-alternator system. It's inevitable that the electricity that they need, HAS to come from somewhere - right?
    It makes no difference from where the power is tapped for use - since it will affect the system's VOLTAGE universally.

    Then the regulator tells thhe ELD - which creates the DIGITAL-EXCITATION --- to cause the alternator to increase it's output above it's normally excited device limits as it can do.


    I'll be gone for a day or so. Be nice to each other..... bye!


    "Life" is what happens to you while you're busy making other plans


  9. #9
    CICERO FAN CLUB MEMBER prefect's Avatar
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    Default Re: Any auto sparkies out there please?

    I think the capacity of vehicle alternators are vastly overrated, some of them could run a small town if it was converted into 400/240v. A lot of load devices are not on all the time but the alternator is working all the time. The Lucas ACR on my Morris 1300 died years ago and I retro fitted a Lucas 25A generator and regulator. Before you scoff it was used for travelling to my pilot training at an airfield 120 miles away and trips to and from the field were in dark sometimes with rear window demister, electric fuel pump, 12v electric jug and heater fan going balls out. Never had a problem.
    Its amazing how Potatoes give us chips,fries and Vodka.

    Get your s*** together every other vegetable.

  10. #10
    Smiling Down On Youse SurferJoe46's Avatar
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    Default Re: Any auto sparkies out there please?

    25 Amps at 13.2 VDC is a formidable amount of potential.

    Rear window ribbon heaters (thin foil usually) and blower motors for AC or defrost aren't pulling very much at all. As for the electric fuel pump, if it's an impulse, it's so rapid that it counts as less than 50% duty-cycle so there's that to not even worry about either.

    But - a coffee/tea/water heater can seriously drive a spike in the heart of an alternator if it's got problems in the first place. Worse yet if there's a bad diode or a dastardly voltage regulator that's having thermal problems.

    As far as the alternator 'working all the time' --- well, it DOES spin as long as the engine's running, but as to a LOAD - maybe not so much. Once the battery's up to rated voltage for the temperature, then that job is shelved and the only thing left is possible lights, electric fuel pump and any creature comfort devices.

    Think about it in all reality --- alternators lead a pretty mundane life.

    For the record, I run a 400 amp alternator on my K5 Blazer for my 12,000 lb winch and my four heavy draw overhead 48 volt halogen aircraft landing lights for use in the woods cutting trees and dragging them out for the last 500 feet or so.

    That takes a lot of recovery power, even though I run 4 group 27F Deep Cycle Marine Starting batteries for storage. I can drive to New York and back to Montana on the starter alone if I have to.

    Once I am driving on pavement though, the alternator has very little to do except be a convenient place for the fan belt to run to the power steering pump.


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