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Old 07-25-2004, 08:26 PM
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Charging system info...............

I copied this information from the AIC (Automotive Information Center) site.................thanks to them.

The Charging System
A. Charging System Anatomy and Diagnosis
If we didn't have the charging system, stopping to give the battery a boost would be more common than refueling, and energy-hungry headlights would make long night drives nearly impossible. But, of course, self-charging has been a high priority with car makers since the beginning of the automotive era, and the components that make it possible have evolved from basic D.C. generators to electronically-regulated high-output alternators.
The most difficult part of servicing a charging system is usually diagnosis. Is the problem in the alternator, the regulator, or elsewhere? Also, if the alternator is at fault, can a repair be made or is unit replacement necessary? I hope the following will help you answer these questions.
The system
A modern charging system comprises an alternating current generator with an external voltage regulator that may be either electro-mechanical or electronic, or an internal electronic regulator. A description of an alternator's construction and operation is in order here. The rotor is composed of an electromagnetic coil wrapped around an iron core and enclosed in two six-claw pole pieces. It receives regulated voltage through a pair of brushes that bear on slip rings, and this causes it to produce a magnetic field. An engine-driven belt spins the rotor inside the stator -- three coils wrapped on a ring -- and this is where the current is induced (one of the reasons the alternator supplanted the D.C. generator is that in the latter current was induced in the armature or rotating member, so the amount of power available was limited by the capacity of the brushes).
But this set-up produces A.C., and automobiles need D.C. So, the current must be rectified (that is, converted from A.C. to D.C.), and this is accomplished by six diodes, a negative and a positive for each stator coil, and three exciter diodes that supply the field with current once the engine is running (when the ignition is first switched on and before the engine is started, field current comes from the battery through the charge indicator lamp).
Essentially, a diode is a one-way valve for electricity. It only allows current to flow in one direction, so it conducts during half of the A.C. cycle, and stops conducting during the other half. With the way the six diodes are wired to the stator, they make a smooth flow of D.C. possible. They also keep the battery from discharging when the engine is off by stopping the flow of current to ground, so they perform the same function as the cut-out relay in a D.C. generator system.
Field regulation
The amount of voltage produced by an alternator is dependent upon the strength of the magnetic field around the rotor, and that in turn is dependent on how much current is supplied to the rotor coil through the field circuit. This circuit is controlled by the voltage regulator, which may be either electro-mechanical or solid state (also known as electronic or transistorized). When the engine is running slowly, or when electrical demands are high, the regulator allows current to flow through the field for long periods of time, or even constantly. As the engine speeds up, the regulator interrupts the field circuit as necessary to keep voltage within the required range.
Illnesses
Symptoms of charging system illness include a low or dead battery, or one that's cooked from overcharging, alternator noise, dim bulbs, and a charge indicator light that shines at the wrong time. Whenever you encounter a vehicle that exhibits any such failing, it only makes sense to check the simplest things first.
The belt, for instance. Do-it-yourselfers sometimes replace alternators and/or regulators when the problem was simply that the dynamo wasn't getting sufficient mechanical input. Suspect slippage if the trouble only occurs when it's raining, or at high speeds. Pop the hood and give the belt a yank and a look.
Next, check for corroded battery terminals, broken wires and big-time shorts (I've seen several alternators in a row burn out on the same car because a missing grommet or a gap in insulation made them work themselves to death).
The main fusible link is sometimes overlooked. You'll find this in the wire that connects the positive battery terminal to the harness. If it's blown, find out what caused the short, correct the problem, then replace the link -- don't use ordinary wire. Be alert for bad grounds and any other potentially troublesome connections.
If you suspect that a short circuit is draining the battery, make sure all accessories are off (remember to close the doors so the courtesy light won't be on), remove the negative cable from the battery and connect a test light between the battery post and the cable clamp. If the light glows, remove fuses until it goes out, which will isolate the leaky circuit.
In the case of a no-charge condition, touch a screwdriver blade to the back of the alternator with the key on. Since there's no residual magnetism as in an old-fashioned DC generator, a strong attraction will let you know right off that the field circuit is complete.
Before you go any further, make sure the battery is in a reasonable state of health so you can trust the results of your investigations. This is a subject worthy of an article all its own, so suffice it to say here that hydrometer checks (providing you can get at that electrolyte) and capacity tests are both still valid today.
BUILT-IN DIAGNOSTIC AID
See what the idiot light or ammeter tells you -- after all, it's there for a purpose, and it may be what made the customer seek assistance. In a basic design, the charge indicator light circuit supplies the alternator with initial field current when the key's turned on, so the bulb glows. Once the engine is started, the field circuit is completed, and it winks out.
If the light doesn't go on with the key, suspect a bad bulb or socket, an open in the regulator or field circuit, or maybe a shorted positive diode. If the bulb's lit when the ignition's off, it's a good bet that one of the positive rectifiers is shorted, which will allow the battery to discharge to ground.
The most common problem indication you'll get, of course, is when it stays lit with the engine running, which should start you on the search for the component that's interfering with ampere production.
Rising voltage?
Using any old voltmeter you happen to have handy, you can perform a basic quick check to find out for sure if the system is charging or not. Simply connect the leads to the alternator output stud and ground, or across the battery terminals, check the reading with the engine off, then start it up and see if it rises (with some regulators, you'll have to rev it to 1,500 or so to get the relay to kick in). Specs vary, but we expect to see somewhere between 13.5 and 14.5 volts.
The most informative quick check possible is to connect a voltmeter across the battery terminals with the engine and all accessories off, note the reading, then start the engine and run it at 3,000 rpm. If the system is working, voltage should rise appreciably above the 12.6 or so you will have gotten initially. A range of 13.5 to 14.5 is common, but check specifications for the specimen at hand. If voltage continues to rise above the upper limit, the regulator is faulty.
Our friend full-fielding
No? Then you can try full-fielding, which is actually a process of elimination: If the system puts out with the regulator bypassed, then the alternator is obviously capable of doing its job. There are various ways of doing this depending on the design -- you know, grounding the little tab in the back of a Delcotron SI with a screwdriver, jumping a typical Mopar's field terminal (look for the green wire) to ground, connecting the BAT and FLD terminals of a garden-variety Ford, etc. Just keep in mind that the idea is to complete the field circuit. If the alternator wasn't producing current, but does now as indicated by a rise in voltage at the battery, you can be sure the regulator is at fault. If there's still no charging, the alternator is the culprit.
Unfortunately, some integral regulator designs have no provision for this test. In late model Volkswagens, for instance, the recommended procedure is to replace the voltage regulator with a new unit, then test output. If there's still no charging, the alternator is at fault.
Maxed out
But voltage isn't the whole story. The most comprehensive check of the charging system is the venerable current output test. If you have a battery/charging system tester, hook it up as the manufacturer recommends, turn off all accessories, and test as follows:
1. Disconnect the battery ground cable and the wire from the alternator's output stud.
2. Attach the ammeter in series between the output stud and the wire you just removed from it.
3. Clip the positive lead of the voltmeter to the stud and the negative to a proper ground.
4. Full-field the alternator as the car maker recommends.
5. Hook up a tach and reconnect the battery cable.
6. Turn the carbon pile off, and attach its leads to the battery posts.
7. Start the engine, let it idle, then adjust the carbon pile and speed until you get a combination of 15 volts and 1,250 rpm. Don't let the voltage exceed 16.
8. Check the ammeter reading against the output specs for that particular dynamo. Generally, you should be within 10 amps. If too little current is being produced, the alternator is at fault. But if the amps are right up there, the regulator or something else in the field circuit is causing the problem.
Of course, you may not have access to a professional-style tester. In that case, put an ordinary ammeter of sufficient capacity in series between the alternator's BAT terminal and its wire, start the engine, turn on all the electrical accessories you can find, and read the meter.
Wavy?
Ripple voltage is the leakage of AC into the electrical system due to a faulty diode, winding, etc. While nobody worried too much about this in the past, the advent of computerized controls made it suddenly important. After all, modern electronics need straight, pure DC or they'll become unhinged and probably drive you crazy when you try to figure out what's wrong. Ergo, it's a good idea to check for ripple voltage whenever you're presented with a problem that seems to have no answer. Various authorities give different maximum acceptable AC in the circuit, so look up the manufacturer's recommendation.
Of course, you have to know how to ascertain the amount of ripple present, and there are several ways. High-tech alternator testers include a ripple measurement feature. Or, you can use your DMM (Digital Multi-Meter) across the battery terminals, and simply switch to the AC volts function. Another possibility is the DLP (Digital Logic Probe -- less than $20 at Radio Shack). When touched to the alternator output stud, excessive AC will cause the yellow LED to pulse.
Inside
If your tests prove that the alternator is the problem, you can either replace it with a new or remanufactured unit, or disassemble it to find out exactly what's wrong. In a vehicle that displays a large number on its odometer, this may be a simple matter of worn-out brushes -- they should have at least .2 in. of carbon left. Test stator resistance by connecting an accurate ohmmeter between two of the three leads, then switch so that all the leads are tested against the others. A typical Bosch unit should produce a reading of about .15 ohm. Stator insulation should be checked by looking for continuity on the 1,000 ohm scale between any lead and the metal ring. You should see infinite resistance. Rotor resistance is taken across the slip rings. The unit mentioned should give a reading of 3.4 to 3.75 ohms. To check rotor insulation, connect the meter between one of the slip rings and the claw poles. Again, you should get a reading of infinity. Diodes are checked by looking for perfect continuity in one direction and none in the other, or by the use of a special tester.
Odd ends
I'll finish up with some random points:
• Some Japanese alternators are full-fielded in a similar manner to that of a common SI-series Delcotron (in case you've never heard, the SI stands for "Systems Integral"). Just use a screwdriver to ground terminal "F" through the hole in the back.
• Speaking of Delcotrons, relatively new CS-series (the initials stand for "Charging System," logically enough) units have no hole for full-fielding, don't use a diode trio, and have a four-terminal connector on the regulator (as opposed to two terminals in an SI). The CS-144 is serviceable, but the CS-130 is a unit-replacement item. By the way, the number after CS, as in "CS-130," represents the outside diameter of the stator laminations.
• Regardless of what caused you to condemn an alternator, before you buy a new or reman unit find out if there's anything left of those brushes. There doesn't seem to be any rhyme or reason why some wear out in 50K miles, while others seem to go on forever, so check them in every case. By the way, making index marks before splitting the case will speed reassembly.
• Some technicians we know are bucking the unit-replacement trend, preferring to fix alternators themselves so they can be sure of the quality of components and workmanship. Parts availability is sometimes a problem, however.
• Current consumption is growing. The Toyota Lexus, for instance, needs a 1,200 watt alternator to handle the demands of its myriad accessories -- that's 100 amps.
• Although 12 volts has been the universal automotive standard for decades, it looks like it will eventually be superseded by higher voltage systems to better power heavy-consumption accessories such as A/C compressors and electrically-boosted rack-and-pinion units.

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Old 09-05-2004, 10:44 AM
Charles F. Smith's Avatar
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alternator

GM late 70s to early 80s truck alternator modified to one-wire operation.
Had the dash pulled down and did revise (reroute, really) some dash wires and when I put the dash back in the alternator failed to work and the volt meter pegs all the way to the right. I've double checked all this and I'm pretty sure that everything is basically like it was.
Remember that years ago the charging system was bad if you disconnected the battery ground cable and the engine died (the supposition was that the alternator would provide the electricity necessary to run the engine). However, that was with a three-wire alternator so I don't know if that is still a valid test with a one-wire alternator.
The engine does quit when I disconnect the battery ground but I'm really prone to think that that disconnecting is not a valad test because the one-wire needs to be "tickled" with 12 volts to operate.
I really would like to keep this alternator because the replacement cost for a chrome alternator would be better spent elsewhere and the local auto electric place wants to charge me $125 to rebuild it.
I'm able to dissasemble the thing but does anyone have any advice on this project and does anyone have the meter readings data to determine which part failed. This may be a case of the brushes wearing out or some other simple mechanical thing - havent even taken the damn thing off yet.
Long winded Huh
Anyway, any advice on this would be appreciated
Charlie Smith
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Old 09-13-2004, 09:29 PM
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Mr. smith---I would recommend the HAYNES automotive electrical manual (10420)----You will not be disappointed.---You can buy it at any Auto parts store.---Complete chapters on starting and charging systems.--Photo's and details on how to rebuild an alternator...
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Old 09-13-2004, 10:30 PM
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Mr. smith---I would recommend the HAYNES automotive electrical manual (10420)----You will not be disappointed.---You can buy it at any Auto parts store.---Complete chapters on starting and charging systems.--Photo's and details on how to rebuild an alternator...
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Old 09-14-2004, 08:11 AM
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The 100 amp one-wire alternator

Turns out that the diode trio was burned and the gauge (Voltmeter) was not working (pegged to the right when the key was turned on). Replaced these and everything is now OK except the gauge reads low by about a volt compared to a reading from the battery terminal on the starter solenoid.
I suspect that I shorted something out while wrestling with the dash unit and instruments but hopefully that phase of upgrading the car is over - bolted the dash back in yesterday.
Had just about given up and ordered another alternator and am sure happy that I can now spend the $100+ on a wood steering wheel instead of the alternator. The diode trio cost $6.00...I'm just surprised as hell that Auto Zone was able to get it for me overnight.
Thanks for the advice and intend on buying the book.
Charlie Smith
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Old 11-13-2004, 04:40 PM
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hey

i have that book


..............somewhere!
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Old 06-08-2005, 02:01 AM
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low v reading

one volt difference between the gauge (dash) and I am assuming you were using a meter to read the other points ( bat terminal) is no big deal. two things come to mind, one did you ever check these points before and note the similarities , and second it just may be a difference in the meter and the dash gauge's sensitivity . if the car has been setting and the bat is a little on the low side just the resistance in the copper connections could load the circuit just enough to cause a slight voltage shift or drop. Not to worry there is no such thing as an almost short , it either is and blowing fuses or it is good to go . enjoy that new steering wheel , I like the wood ones myself , the ford mustake one with the rivets all around the wheel looks great in a 34 ford , matching wood dash of course....later
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Old 06-13-2005, 12:46 AM
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Man!!! Way mucho Info!! Powermastermotorsports.com page has a real good FAQ on alternaters.
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Old 07-21-2005, 02:30 PM
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Ok, well done. However, I've tried 3 different voltage regulators in a row but it still shows 18v. or more when reved up! I don't want to cook another gel battery! Could a faulty wire from the alternator back to the regulator do this? ie. maybe the reg. isn't getting the message?? It a Ford system, actually a 302 out of an '80s Mustang in my old '49 F-1. The wiring is a zoo as I bought it as is & don't want to tear it all out until the off season!
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Old 07-27-2005, 08:24 PM
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charging system

http://www.ford-trucks.com/forums/ar...ring%20diagram
Check this link it shows a very straight forward wiring digram, if your wiring is good, check the path to ground from the regulator base to the bat.The regulator gets to ground through the base. Where is the regulator mounted? Use a meter, the setting is ohms and the reading is 0 as in 000. If no numbers , indicates an open, a large number indicates a parshal open and depending on how large the number is will effect the operation of the regulator. The regulator must have ground to work. It is really a relay that opens and closes . Considering that 3 regulators have been installed I would look elsewhere for the problem. Wiring or ground. You are describing a charging system that is continuously charging... hope this is of help. The charging system is simple it just needs to be wired correctly to work
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Old 07-27-2005, 08:51 PM
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when I put the dash back in the alternator failed to work and the volt meter pegs all the way to the right. I've double checked all this and I'm pretty sure that everything is basically like it was.
Remember that years ago the charging system was bad if you disconnected the battery ground cable and the engine died (the supposition was that the alternator would provide the electricity necessary to run the engine). However, that was with a three-wire alternator so I don't know if that is still a valid test with a one-wire alternator.
The engine does quit when I disconnect the battery ground but I'm really prone to think that that disconnecting is not a valad test because the one-wire needs to be "tickled" with 12 volts to operate.

Long winded Huh
Anyway, any advice on this would be appreciated
Charlie Smith[/QUOTE]

that engine run test is still good, but you may need to be @1200rpm , the wire that you are disconnecting is the wire on the battery . If it worked before you did the work on the dash.................................. and does not now work. If I were you I would go back and start there , also solve the problem that you can see..... that volt meter is not right and that is were I would start looking. Fix that and that could solve all. Troubleshooting is fixing the errors that are obvious. Fix what is broke and you will fix the problem....

Last edited by pepi; 07-27-2005 at 08:53 PM. Reason: extra word in post
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Old 11-26-2005, 09:53 PM
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