Alternator hunting and how-to?

It is critical in certain vehicles.

One problem with selecting an alternator with a greater-A-supply than normal is initiated in the tolerance of some of the wiring standards used in your vehicle. for instance, the ignition wire only needs a small draw to the relay swtich that jumpstarts your car. And the wiring in those areas are fairly tight especially in later models.

Its possible, by putting in a greater supply, that your alternator will burnout the wiring along anywhere along the connection to relay pin 30.

that's where the major danger lies, such; anywhere the tolerance of the wiring may be compromised.

What I would do is use the alternator and add some cheap resistors (between 5R and 2R @ 2W), connect to all your relays at pin 30. not all of them are in danger, only those with tight wiring. And those relays have a large working tolerance so it should work and safegaurd you against the possibility of wire melt. Shouldn't cost you more that an extra 10 maybe 20 dollars.

Gl

Dear Guest, I hate to be rude but your understanding of electrics is completely and utterly wrong. Please remember Ohm's law.....try to understand it fully.

I would go as far as to suggest that you probably know better, but wanted to generate some interest from those who understand such systems.....

...but just in case you really believe what you wrote, read on:-

The only place where more current can flow (when replacing an alternator with one of the same nominal voltage, but a greater current output) is between the alternator and the battery. Generally speaking, this is the thickest bit of cable on a vehicle. The same cable is generally used from the battery to the starter and can often handle 400 amps or more when starting!!!! (depending upon motor size etc)

Thus the relatively light currents of charging will not affect it in anyway at all.....

Also, the circuits you mentioned, may not work at all if you start adding resistors to them as there will be no difference to the voltage in the system after changing the alternator for even quite a heavy duty version!!! The resistors will just cause unplanned extra voltage drops......to below requirements.

For example:- Circuits that took say 1 amp before the change, will still take 1 amp after the change as nothing has changed in the circuit......only charging current will be increased when the battery is not in its fully charged state and the engine is running. Nothing more.....

Agree with Andy Deutschland on all points, particulary 1st sentence.

In fact many people install fatter alternators e.g. to power camper refrigerators, phat sound systems, etc.

Only wonder about this passage:

"...is between the alternator and the battery. Generally speaking, this is the thickest bit of cable on a vehicle. The same cable is generally used from the battery to the starter"

- I ain't never seen alternator - battery cable as thick as battery - starter cable! But maybe I never paid attention or looked closely enough, will have a look tonight!

best regards /rfg

If it is not quite the thick cable I mentioned (you could be right!), it is usually a very heavy bit of cable because it is going from the engine (vibration and movement) to the car chassis area (relatively still), so it must handle this vibration & movement without breaking.

I am now going to have a look at my car and try and see that cable....

When I used to build kit cars as a hobby, I just used the same cable as for the battery....maybe I am remembering that and not what real manufacturers do to save a penny or two!

Anyway, beefing up that cable should not be a problem......!

Thanks for drawing my attention to this point! It could be important!!

Andy, You are in error. The wire between the battery (or batteries ) and the starter motor is always the very thickest. The reason is that the 600 -800 amp cranking amps is possible on a cold morning in hell. For alternator rated max is only 95 - 130 amps, much less , thus the wire from alternator to battery is less of gauge (higher gauge number).

We could say you don't understand ohms laws.. but.. you know its better to say .. hope this helps you! (positives beget more positives and 'friends'. )

By they mining operations producd gases too, and heavy metal pollution as does nuc fuel mining.

YES disagreeing is great, accuracy paramount, .. but please don't talk down to even the rawest rookie (you might be disaffecting a future possible famous scientist who may be now only 18 years old). Would you rather they think of engineers as arrogant creeps who make a person feel so low that they hate us?

ANDY, otherwise keep up the good inputs. (watch below)

TO GUEST: Nice thinking except the ignition wiring you mention would not draw more energy in itself unless something other were connected as well (as an add on). For existing wiring to add on for example a camper fridge, you would need to make sure the wire all the way to battery is sufficient gauge and also install an independent isolated fuse to make sure the wire did not melt. The alternator charges the battery and would have not affect the ignition draw in a dangerous way.

BUT you are right in that if the wiring between the alternator and battery were just barely sufficient for 95 amps and a person changed the alternator to 130amps.. yes that wire could melt, concievably, if it ran at full blast for a long enough time.

As I believed I mentioned elsewhere, it is usually very thick cable because of the fact that it runs between a vibrating engine and the chassis area. eg. fixed.

I am going to try and locate the cables in question on my Mitsubishi, on its 120 amp Alternator.....and compare the relative sizes.....

See you later!

WHAT?

are you aware that there's a transistor to regulate the feed to the battery? when the battery is fully charge the current is switched.

are you also aware that the car runs from the power of the alternator over the power potential of the battery, and it is when you run things like the Air Conditioning, Wipers, Lights etc that the potential of the battery may kick in and assist with operations?

It will work, and a relay usually has a range of around 10 A(max) to 100 mA (min)(sometimes less, but they usually have a consistant standard), thus with that in mind, 2R should be ample: so you are able to add in resistor WHICH WILL LIMIT CURRENT. While limiting the current, it will also safeguard against the potential of wire melt. and it is working on the draw of the relay, not the current it switches.

It will not cause unplained extra voltage. So you really seem to not know what you're talking about? are you aware of Krichhofs Law (not sure of spelling) which means voltage drops!

~~~~~~~

bottom line to the person who created this thread, I've seen the results of usings a larger alternator. I've had to strip down an entire wiring system to find a fault with a unique tell tail sign. I've had to strip away a front windscreen thus to remove the dash, thus to remove the heater and air conditioning unit, thus to reach a wire that had melt, thus to replace that wiring with a grade that could handle more current. rather than go through all that rigmarole, simple place resistors to limit the current. It will work becaus those relays have a large operating tolerance.

So regardless what these guy may say, be wise. It's about the handling capacity of your wiring!!! so even though they bring up fridges and the like, they seem to not understand that those obviously have a greater toerance capacity, which is why they work.

of course, I'm only assuming you still can't find out and will never find out the values of your alternator, and find a replacement with the same value, and that you're looking for a cheap alternative rather than having to recore the entire coil. assuming that's all it needs to be fixed, and while you're at it, if the recore option is what you decided to do, also you should replace the brushes, and id look at the armature and check for groves, it may be the case that that alternator is old, and therefor some ware in the armature exists also (two options there, have it resurfaced or replaced). So thats a rather expensive option. but it should last you years.

Guest,

80% of what you wrote is either wrong or misplaced, sorry.

By the way, you spell it Kirchoff and his Laws.....

It has little to do with this thread, Ohm's law is more than enough!

you don't know what you're talking about.

a resistor in series with a relay is applicable to Krichhoff's law!

oh and by the way, you spell it "Krichhoff's" 2nd Law

oh, and also... the voltage tolerance of those relays is aroun 7 V to 30 V DC.. so your point about voltage spikes is rather a mute point also.

Wrong again!!

You are not having much luck tonight are you?

Only if you want to be obtuse!

Ohm's law will work well for you in your example....

the only thing blunt of thought is some of the considerations given in your replies.

you mention voltage spikes caused from a resistor placed in series with relay and failed to see that Krichhoff's law is applicable. so one can expectage a small voltage drop and not spkie... and if you're going to correct the spelling, you could at least make sure it's correct. I'm mean come on, I wouldn't go calling anyone as wanting to be obtuse when you make such a basic mistake.

If you knew the wire was damaged and needed replacement. why not run it independently and save yourself some work, maybe a splice in front of the firewall; by the writing and questions I can see the person is no teenager and best answer would have been to recommend replacing alternator with one of the same rating, period. A question creating controversy rendered desired results and much confusion.

sometimes, to find a fault is very difficult.

once it is found, alternatives can be assigned.

Let me describe a fault and you tell me how you would go about finding it.

everything live is now earthed such that your battery will flatten in less than 20 minutes? how would you go about finding out where that fault lies? the problem is such that when ever you use a circuit tester on the live wire, no fault can be found as the earthed bypass means that the tester light will not work!

I was aware of way's I could solve the issue once I found it, but it was scheduled for a full vehicle of inspection certification, so tricks might be exposed in such a test, and it would fail, and at over 500 hundred for a test, its rather expensive to take a risk.

And anyway, this thread isn't mine, and the advice was given as something that the author of this thread should be aware of. Otherwise, the author may face a more expensive lesson further down the track.

So, I wouldn't take the advice of these guys that obviously haven't considered the complete wiring system, or the potential for a relay to current hog if the potential for such exists, and thus the effects of that hog on wiring systems that are design for a less tolerant capacity. Or the advice of people who don't even understand how an alternator governs the operations of the vehicle, and who don't understand that the battery is used to supply backup, and for vehicle ignition.

But hey, the author can risk running a larger alternator, and the vehicle may even function fine as it is.

Dear Guest,

to say something nice about such a post is very, very difficult, but I did find something, your spelling, grammar & punctuation are excellent, which is something often missing on CR4 (I include myself in that remark!).

Im sure you have some nice qualities too Andy.

Thats the first time anyone has ever remarked positively about my punctuation and grammar. appreciated.

thanks.

Go to a after markets parts store and get a rebuilt one like the one that came out of it is the easy way. The other is to rebuild it your self unless its a sealed unit. If it is replace it with an old Delco. I can replace the brushes in the dark without taking it off a tractor in 15 minutes . They go though brushes ever 2 or 3 hundred hours running out in the dirt.

When I was farming I just carried a spare Delco and swapped it out with what ever failed. It used to cost $35 buck to get one rebuilt I expect it $70 from the same place now.

GC

Firstly, you should go to another Ford dealer and ask to look at the "correct" part, because it does happen sometimes in this trade that parts that are "ALMOST" identical, get put in the wrong bin under the wrong part number.....I have seen this happen too often to be even part of a joke!!

Even if the correct(!) version you were offered is the one that they all have, but only the cables are too short, for example:-it lines up correctly with the pulleys etc., then lengthen the cables!! Also get the old one rebuilt and store it in plastic bags till needed!!!

To answer your questions, alternators are designed to put out a maximum voltage, usually around 14.2 to 14.4 volts (it can be a tick more sometimes), which will get your battery recharged at the rate decided by the maximum current that the device can put out. Once this voltage is achieved (battery is charged) then the battery just "floats" and takes almost no more current.....while the engine is running, the alternator supplies the load for anything that you switch on like radio & lights, up to the maximum current of the alternator, above that the battery helps as well...

Taking an alternator with the same nominal output (either 12 or 24 volts) but with a higher current output,will just recharge your battery quicker, no more no less, important if you only use the engine intermittently for short times.....a "nice to have" feature....

If you run the engine generally for long periods and do not have a lot of other stuff switched on as well, then theoretically you could go to a lower current device, but I would not recommend it as the price differences are usually minimal......as Tim Taylor always said on "Tool Time" - MORE POWER is really better!!!!

This whole problem is a lot simpler than most people think!!!

Depending on the age of your Ford Ranger, you might want to try a Mazda dealer. Since the Ranger and the Mazda truck were the same. Or you can try any good parts supply house or a company that rebuilds alternators.

A comment on the mounting question which might help. Some years back I used to repair Lucas alternators in UK. The "handing" of these can be altered. By removing the 3 through-bolts the drive end can be rotated so the adjustment strap hole becomes the mounting hole and vice versa. Sometimes the adjustment strap hole is threaded for a setbolt so need to drill out the thread, and use a bolt and nut for the new adjustment point (M8 or 5/16" in UK).

I'm not sure it works on your Ford alternator but it's worth checking. I'm trying to remember whether you can also alter the connector block clock position, if necessary. Probably not as it's fixed to the inside of the non-drive end bracket.

If I can add anything to your other queries I'll post again.

Codey

Well put!

Jeez man - forget the dealer for such common parts because you can save a ton of money at Auto Zone or Pep Boys. Also, Look up your parts before you buy them - I.E. autozone.com - Alternator I would have looked it up for you, but you didn't give me enough information.

The main three ingredients you are looking for: (1) Belt alignment. secure fit, (2) Energizing input compatiable to wiring (if you don't send 12v in from battery system unit will not charge) in other words do the input and input plugs align electrically and physically, (3) sufficient amperage, more is better, not harmful in this case.

The car company does not use the same current capacity wire. They even skimp incedibly on the ground cable because of the short length.

Most custom builders do, again more is better!

BTW I have worked on cars capable of drawing 1000's of amps continuously.

JC Whitney has parts that I have put on my ford truck before, in fact you can buy the guts to an alternator and rebuild just the internals to it so it still fits. I converted my 70 amp std alternator to a high output 105 amp model this way. Ran it over 100K miles without an issue and in fact you can put any size (amp output) you want and your truck will only consume what it needs. Your voltage regulator and battery will stay in sync with your output needs. Good luck. Kevin

Sorry I don't have time to read all the posts except the first reply by Gl telling you a big alternator will fry your wires. Thanking Gl for at least his/her kindness in replying and trying to help, the advice is not at all accurate . . . . but not harmful to your truck if you followed it except you may not find the exact alternator, which is the basis of your post. And without reading on wards I know 5-6 posters here will tell you the same.

A small alternator rated 60 amps can also produce hundreds of amps if that is what you demand from it (like a short circuit). The issue is that those hundreds of amps will only come along for a few milliseconds before it blows up some internal components rather nicely.

At the risk of duplicating what others have told you:

First, what is wrong with the old one? I've changed regulator modules before, bearings, brushes, stater windings etc and repaired alternators when I had the time and could buy repair parts; now 'on line' it is more easy. I had a $3 bearing go bad in a $150 (exchange price) alternator and just took the old bearing to a bearing supply store and they matched it from stock. 30 minutes of work plus one trip to the bearing store was my time investment.

Ford stops making parts for anything 10 years old. Wrecking yards are where I get my parts if AutoZone or PepBoys, NAPA, etc doesn't have them. CarQuest is one of the best for parts and people knowledge.

******

1) Bigger is better if it will physically fit. Amps is what it is ABLE to produce without heat damage to the alternator's internal components and has NOTHING to do with overcharging anything . . . period.

2) If your old one had an integral regulator in the back, then your new one needs that also and will connect to the same 'flavor' plug. All the smarts for sampling voltage and excitation are inside the existing plug (wires routed to all those things in the harness), so match the plug and you are 100% OK for regulation smarts. The single large wire on the insulated alternator post is the 'charge back wire' that eventually ends up 'back charging' your battery via some protective devices. Disconnect the negative lead of your battery first (in case your wrench hits the frame by mistake) followed by the positive (also, in case your wrench hits the frame by mistake - now the frame is ungrounded) otherwise there is a high risk of your small wrench touching the frame when tightening this nut on the alternator post and you may blow up the integral regulator not to mention weld your wrench to the frame before blowing a fuse link.

3) You CAN index alternator housings. One problem is that when they decide where to mount the regulator, that tends to be soldered in place inside. So it is where it is with respect to any mounts on the back housing and plug alignment. Just take off the long bolts and index the front housing where the 'tightener' mounts. If there is a indexing problem with the back housing with respect to where the regulator plug is and the back mounting bolt, you are screwed. Then the whole stater winding needs to be indexed and this is more complex, but, I've done it in emergencies where no one had the right one and wrecking yards didn't have one also.

Email me direct for more.

You know petro,

I use to think potential wouldn't effect the lines that flow of it. that was until I had to change wiring that melted 20 minutes after a replacement alternator was used.

It was obviously a short, and I couldn't find a wiring diagram for the model/vehicle I was fixing. anyway, it would have been good value to check the diagram, and estimations of current and voltage down lines. if in one area, the potential was higher and therefore drew more current, and the control line in was smaller than the load, melt/excess-heat would ok.

So the advice I gave, though lacking in proof of actual cause and effect, takes into account all information that was available to me at the time I fixing the vehicle, and are safe option oriented. I would rather get the right parts, but I don't see why resistors wont work, do you?

Hi guest and thanks for your reply

Are you the same guest (Gl) that is getting into spelling matches Kirchhoff or Kirchoff (or whatever) or are you a different guest? Why not join CR4 please so we can know you better?

Well I can now see why, if you are Gl, that you became worried about bigger alternators if you changed melted wiring after putting on a new alternator. Look at these guys who openly WANT you to buy their alternator as it puts out more amps than the original one.

I think your short circuit may not be related to the larger alternator, but, maybe due to the new alternator to support a short longer with higher voltage. Higher voltage with the same resistance pushes more amps and melts more wires. This is Ohms simple law. A new alternator may have had a much better voltage regulator, or a regulator not kaput (which could be why you switched alternators). Perhaps a short blew up the brains of your first alternator, and the new one had better field forcing and didn't allow the short circuit potential to drop near zero and the forced field allowed the short to be sustained. The battery must have been kaput also as short circuits are stupid and don't choose where the voltage comes from . . . the alternator or a charged battery (it is the same circuit when installed). A short causes the voltage to drop and the regulator will go to full field to try to keep it at 12 VDC and should be regulated to about 16 -18 VDC at full field and normally around 14.5 VDC at normal heavy charging loads. A short has theoretical infinite amps limited only by the resistance of the melting circuit. Now, I will tell you that you can be partially correct on big alternators causing bigger problems with higher amp capability since if a smaller alternator destroys itself at 200 amps and a bigger one at 700 amps then the bigger one melts more wires for a longer time. This is related to the impedance of the internal windings under short circuit. In the case of a short circuit, bigger may not always be better, but, both a small one and big one will melt control wires very nicely !

I'm not sure I catch your resistor comment.

no,

the problem I faced was very specific, and it happened across a small wire that handles 0.2 amps times 4 wires. so its capacity was 0.8 A

it was this wire that suffered fusion to the chasis that was eventually routed to pin 30 on the relay, and it was the ignition wire. But it is possible that the problem may have been caused from something else, but hardly likely... 9 times if not 10 times out of 10 it will be the load that causes wire melt. So there's really no other cause that can be considered.

and I suspect the larger capacity of the new alternator which was about considerably more, as tho the newer one came out of a similar modle and therefore fit straight on, all the fuses in the modle it came out of were rated 10 A greater.

There's nothing wrong with greater Amp potential, so long as the circuits can handle it.

Actually based on the last information I would rather say that something caused the first regulator (and maybe the alternator to go out). Then the second regulator alsoe also went out immediately. This led to "overcharging" the battery (and subjecting whole electric system to higher voltage). This can cause things to melt (higher voltage with same R means higher amps also = higher power being dissapated ). V=IR Where I is amps.

Power = VI (many times written as VA). This means that Power = I x I x R = I² x R

TO GUEST: The battery has way more than 130 amps to give (just cross + and - terminals with a wrench is you want to see how an arc welder works and fireworks too! ) So a new alternator of higher power if regulator is working correctly should not damage a good system. Your system appears to already have some problem which may have caused the original alternator/reg combo to go bad. Perhaps when someone was working on it at some other time they inadvertantly pinched a wire somewhere in the system? Cheers to you!

Thats not such a bad suggestion, which is why I mentioned two things earlier, in earlier post. =in reference to the increased voltage-- being; that I would have benefited from viewing a wiring diagram, and that I made all my calls offered for consideration to the author of this thread based on all the information available to me.

Your reference:- =in reference to the increased voltage--

Can only happen if the regulating part of the alternator is damaged in some way....I don't even believe that damage to the alternator wiring could have this effect either UNLESS it is an old alternator with a separate regulator that for example Volvo used up to the early 80's.

All good working alternators are set to produce current at a maximum voltage, usually on or near to 14.5 volts.......this has been found to be high enough to charge the battery in a reasonable time, and low enough not to overheat or gas the battery.....

Well put!

Forgot to mention the amp rating is always stamped on the housing, like 47A, or 65A somewhere easy to get a mechanical stamp on a housing at the factory.

What are you saying "indexing " is? Is it a way to change on alterator to mount on a different side of the engine what ?

Indexing (US term) is what the other gent above terms 'handing' (European term) and in this example means to "move over" without the need for different parts. i.e. Open this link and study the long mounting boss juuust hiding behind the fan shroud at the top left. This is the pivot bolt mount that has a long bolt that threads to the engine block, but it is totally part of the front housing, and the little tab below right is the adjuster pinch point when a bolt threads in after it is placed in the slot of the belt tightener arched brace. Now, what if I mount this and learn my plug in point is completely on the wrong side near the exhaust manifold or another inaccessible place? I loosen the small case bolts (you can see two of them) ad index (rotate) the back housing around to the next case bolt point and bring my plug around where I need it. here is a better view of one easy to index:

If you have an alternator like this where the pivot bolt catches the front and rear housing, you can index it. Sometimes you can index just the 'regulator'. This indexing is a way manufacturers can use the same alternator on different models and was popular in the 60 and 70s when we cared about such things are commonality. Now there is an entire new P/N for everything in an attempt to sell more parts. Starters we famous for needing to be indexed so the Bendix solenoid would not hit obstructions on certain models. The different P/N often times only indicates the indexing on virtually the same identical part.

If you have an alternator like this where the pivot bolt catches the front and rear housing, you can index it.

Should be can't index it !! Not can. I typed too fast. Plus, my mom rasied an idot ! (but don't tell my sister I critised her on CR4, please !)

Right , thank you, good explanation petro! So indexing is a way to use the alternator or starter on different vehicles in situations where something simple like the wire plug in on the wrong side . Reminds of me installling a Delco Remy Alternator on a Mercury Capri and driving it cross country. The Lucas went bad so many times I said to hell with it (90$ each time).. and got a $5 delco out of junkyard .. at first I used strange mounting scheme and a manual switch to 'estimate" the charging needed. yes weird but it did work (after a fashion).

Yup. I work overseas a lot and you would be surprised how I've learned to modify parts to get them to work. I made a bolt once by filing grooves in a piece of re-bar with an triangle file and smashing the top into a square ! A fan belt for my car which threw it off 300 km from everywhere in the desert by sewing my ripped shirt into layers with the 10 small sewing kits I keep in my bag from hotels. No AutoZones in Kazakhstan.

You are funny! How about this one, a girlfriend was supposed to visit me out in desert to camp. She arrived on emtpy tank of gas. We cut up the window washer hoses to make a siphone hose and got her enough to get back home. !!

Another time.. cutting wood in the mtns of oregon.. got stuck in snow. friend deserted and started walking out.. (30 miles maybe) I got the come-along and cut long skinny trees to use as 'chain' to give me enough rope to work my out.. caught up with half dead friend and saved his life!

Anyone who is unsure about Kirchoff's laws (some of our Guests!!), should do some reading:-

"Both circuit rules can be directly derived from Maxwell's equations, but Kirchhoff preceded Maxwell and instead generalized work by Georg Ohm", which is why I always refer to Ohm as being enough for this minor problem!

Anyone who quotes Kirchoff in such areas, just wants to darken things down for those with less understanding!!!

Goto Wikipedia for a fuller description!!

Much has happened here while I was making a response, but let me post anyway and then go back and see all the newer answers.

Consolidated IP Response:

First the "practical's." One reason for resorting to dealers involves scheduling and logistical considerations (including that there is no back-up vehicle at this time. But the self-help advice about Delco and such is appreciated and could come in handy at a later time. As far as I recall—this would include ass'y plant coding in the VIN—my single-owner, '87 Ranger XTL model was built fully converted to decimal, but only the 5-sp manual (4-sp w/ overdrive) was a full-up Mazda inclusion at the time. (Unfortunately, that transmission, before repair of manufactured fault, proved to be a book price "de-valuator" on the resale market.)

At a fundamentals level, Andy's information (including the last sentence; except that the "whole problem," as exemplified by the multiple original questions, was not directly addressed) seems to comport with what I anticipated—what I hoped for: namely—and in a nutshell—that nominal alternator output is manufactory matched to battery capacity (size) and, in turn, battery size is matched to engine-crank-resistance-required starter demand (primarily) and chassis electric loads (mostly offline such as lock and window motors, high-output amps, winches, sometimes resistance de-icers, and such) secondarily. And vice versa on all counts. So I gather from the light Andy has shone, that if there is a practical limit to how much alternator output excess…it is market dictated by the alternators available (and not available) for my vehicle and others in its "class." In other words, if it's recommended & sold OTC (over the counter), and fits or can be made to fit, it should work…even if it could (?) peg the needle on my AMPS gauge ;-). Did I get that part right? …now for the less fundamental issues…and to bring repair "progress" up to date from when I first posted. (Seems this will take us down another path as you will see.)

Perhaps I didn't state it clearly enough, but I did consult two dealerships: one (the first) which has shown evidence of malfeasance; the other which has never given cause for mistrust. From these two I was apprised (eventually, and by the techs, not the dress shirts or ties, at the second dealership): that "all newer" Rangers and "some" older Rangers use a "130-A" alternator, whereas most, older Rangers used a "95A" alternator. However, the first parts counter's Ford catalog specified a unit which, when pulled from shelf and examined by the parts man, was described as a 47-A Motorcraft replacement (one of two) for my Ranger model's original alternator. It was this seeming discrepancy—and my sense that the techs might be unwittingly referring to ratings (maximum loading before bad things happen), and not nominal output, that led to my questions at the start about ratings. The second, trusted dealership parts counter (phone) gave two catalog-listed (re-mfd replacement) units for my '87 model—actually, they were for all year models, 1982 thru 1989: one a (nominal) 40A (same pn and, presumably, the same unit as the "47A" at the first dealer; the other a 60A. (With only passing knowledge of motors/alternators, it occurs to me—this apart from possible confusion about "ratings" by the techs mentioned above—that "straight-line," safety de-rating of their (the techs) "130A" and "95A" alternators would yield respective outputs roughly compatible with 65A and 47A average total (battery/starter/engine/chassis) loading; hence, the nominal 40A and 60A units recited from the Ford catalog. So my objective, in part, was to get an engineering perspective on the confusion…whether the tech and parts people are talking about the same things without knowing it. But, back to the status part…)

Of the two FMC catalog-listed Motorcraft alternators, neither is in stock locally: a few of the 65-A units are warehoused over a hundred, and several hundreds of, miles away. The one locally available 40A unit…well, it's no longer listed as available…because I purchased and took it home Saturday; Although I have doubts that this unit was for other than a strip down, base, 4-banger Ranger, I bought it (with option to return it) both, to assure its timely availability if it is the right replacement and not a downgrade in my Ranger and, as well, as a hedge against any secondary markup or other shenanigans by the dealership. That is, I will have the option to make it available for honest dealer installation, or install it myself.

But this defensive measure has not been without problems of its own which invite another question needing CR4 expert advice. Here it is. On the 40A unit that I now have, the clocking of connectors is correct, but the pivot yoke and belt-tensioning mounting points are straight-mount—respectively at 6:00 and 12:00 (o'clock)—while the originally installed…has a frame with 6:00 and 10:00 mounting points. It will not install in the straight in configuration. So what I need now is guidance. It appears to me that I might be able to convert the new alternator to fit my Ranger if I can remove and exchange the mounting frames between the new, and my old, alternator—and connectors would remain in same position; so it appears no re-clocking would be needed. But I'd hope to get some guidance from someone who's done this—split an alternator from its mounting frame—before taking any chances.

Gentlemen, I realize this has run long; I've tried to answer and describe…as briefly as I know how without being too hard to follow. Your understanding is appreciated. Later, I might like to add more—about how these alternators can have defects which, it seems, Ford dealership test equipment is unable to detect—and how it seems that some dealer service departments have learned how to exploit this incapability to extract additional money—much money—out of customers' pockets; if anyone is interested?

As an update excellent, but you do not seem to have fully understood what many have already mentioned about compatibility with regard to output!!

Of course that may not be a problem, especially as your "new" one would appear not to be as many amps as your original....as long as you do not overload it with switched on accessories all the time, especially in winter!

Without upsetting anyone, did you understand enough about "indexing" etc from an excellent post or two (I forgot who wrote them sorry!) to allow you to do the rebuild? If not, return the new / refurbished one and get your money back as once you have opened it up, its yours!! Then go and get one that fits, even if it is a higher amps than before.....you do not want to be taking something like this apart unless you really know generator construction and electrics......sorry.

At worst, you could cause a fire....

Hello Andy - not so much a reply to yours, but a general comment or two.

Original post referred to clock positions. I said hand because the different configurations fit (usually) on left or right side of engine. PetroPower called it indexing. Variety is the spice of life!

I would have thought the only problem of a higher output than original is if the main cable from alternator to battery can't take it, because when the battery is low and revs high enough current is at rated max of alternator. Anything else only draws same current as before. Of course if more accessories are added care needs taking, but there was no ref to this.

If there's a short circuit somewhere, as some posts have mentioned, there's a problem that needs fixing, irrespective of alternator output.

Does anybody know what limits alternator current? I've asked a few electrical types and never got a satisfactory answer. Generators (dynamos in UK) have a current and a voltage regulator (sometimes combined for cost saving but still limiting current). Alternators only have a voltage regulator. Would max current be the same if alternator output were taken straight to earth, rather than to battery? I expect it would, but I'm not about to do the experiment on my vehicle!

Any comments appreciated.

Cheers.....Codey

My understanding of indexing was that he can turn the end covers, in relation to the main body so as to allow the mechanical position of the alternator to be turned, so that cables can be plugged and it can be still mechanically adjusted to fit the engine.....

...not to put it on the other side of the engine per se, but of course it may be then possible to convert an alternator for one engine for it to be on the rh side and for another engine type on the left.....

....but maybe I am completely off track on this point, sorry.....

Hello Andy - need for indexing is so the adjustment hole is in the right position for the bracket on the engine. This is if the mounting holes and adjustment hole are 120° apart (as they often are), it obviously doesn't apply when they're at 180°.

Usually the cable is long enough so the connector clock position isn't critical.

Cheers...Codey

Now this thread is becoming more interesting again.

Beyond built-in fuses (which may or may not actually exist), what limits the output on an alternator, or any generator, is Physics. Basically, How Big Is The Unit:

- magnitude of the applied magnetic field, through which the rotor turns (taking the
engine as an essentially limitless power source :-)) , and

- thickness of the (copper) windings.

I suppose if you have an automobile alternator rated at e.g. 65A it can probably supply more (150%? - who knows), but eventually something (windings or the connections to them, the regulator, etc) will assume the role of fuse (i.e. melt itself open).

They can see hefty loads - e.g. a dead battery (really dead, i.e. a couple of cells near zero volts..). I suppose the regulator is set up to throttle back the magnetic field to limit the current, but I never looked into it. Ask Bosch.

Regards
rfg

Hello RF guy - unless things have changed in last few years, rated output is max the machine will put out. I've seen curves of amps vs speed where it topped out at 66 amp (which was the nominal rating) at ~ 10000 rpm. The test would be done with (presumably) a battery connected and the voltage regulator bypassed, which is quite easy to do with a length of wire. This puts the full output voltage on to the field windings. In normal operation the voltage regulator works by reducing the field voltage as the output voltage approaches setpoint, 13.5 - 14.5 volt for a 12 volt alternator.

But with a dynamo there is also a current regulator. Electromechanical type with vibrating contacts (in series) limiting field voltage when output voltage or current reaches max. If you bypass these, or just hold the contacts together, the current goes as high as you like if you rev the engine, and soon damages the dynamo if you persist.

Why this doesn't happen with an alternator is my query. It might be just due to the resistance of the output windings, but if so, why weren't dynamos built same way? This would presumably mean a cheaper dynamo (thinner wire) and cheaper regulator.

Cheers...Codey

Sir Codemeister, ok, clearly you know a lot more about this than I do, I was just making assumptions, based on playing with cars and what I know about 500MW turbo generators :-) But it's just what I was saying: they've got some kind of (very primitive, but effective) gizmo to self-limit by throttling the mag field back.

I would assume alternators work exactly the same way
It's surely not the resistance of the output windings! - they'd get HOT..then become a fuse!

No, I assume they're regulating the field, as you say. Probably with some simple

(read: CHEAP) semicondutor chip. I'm sure there's stuff out there that explains it.

BR
rfg

You asked:-Why this doesn't happen with an alternator is my query. It might be just due to the resistance of the output windings, but if so, why weren't dynamos built same way?

My personal take is that the electronics built into an alternator, limit the maximum output current to a safe level, probably by limiting the excitation. Although the way the gap between rotor and stator is designed can also have some special leveling effects to the output voltage / current curves.....or maybe is a combination of both!

Dynamos were designed basically I believe shortly after the first world war, and as such were not able to use electronics to any great degree.

Commutators (Dynamos) also have an irritating habit of causing a whine on sensitive audio and radio equipment, a problem which slip rings do not have!

I am sure that a dynamo, if designed today, would exhibit a lot of those safety features that you would have liked to see.....but could they get away with a brushless version, I personally do not know....the last DC generators I worked on still had dozens of brushes and a commutator!! But the wonder of modern electronics should make it possible....

Andy - you wrote My personal take is that the electronics built into an alternator, limit the maximum output current to a safe level, probably by limiting the excitation.

Unlike a dynamo, there is no detection of output current and hence limit of excitation. The regulator only looks at output voltage. Some early alternators had electromechanical regulators, mounted separately, as somebody posted. But they only detected voltage.

Cheers....Codey

That is very interesting, then I guess current limiting only comes from the stator to rotor gap design......as actually happens on very large AC generators too.....

Read #15 . . . I know there are too many posts here. The rating of any alternator, even a 10 MW on a 15,000 HP engine (my world) is a definition of what the unit is able to produce under the specified circumstances and yield acceptable life cycle costs and value. So, I can assure you a 65 A alternator can put out 500 amps or 50000 amps but what limits it from doing so for a long time is the components inside. It can put out 65 A under the design conditions (circumstances specified such as engine area temperature, X speed, X altitude, X expected lifetime, X temperature rise, X side load on the bearings, X voltage range, etc), and life expected might be 5-10 years if you don't exceed any of the design parameters and it gives value (cost versus lifetime). Start changing anything, and the curve moves to the left. So if you car's 'load' can suck 85A with everything operating, then this is a bad design to have a designed 85 A load being fed with a 65A alternator. It will put out the 85A, but not for long.

Just short the output post to ground and you will pull thousands of amps within 2-3 milliseconds but the components will instantly heat up and begin to throttle the amps pouring out as resistance rises instantly and things will melt until you have an open circuit, normally a diode or some solid state thing in series with the load. Can the alternator turn 2000 RPM ? Sure. Can it turn 20000 RPM. Sure if you were able to instantly snap it up to 20000 RPM but it will fly apart 1-2 milliseconds later.

So what limits the alternator rating? The application of it's operation, not the nameplate.

What limits the amount of beer you can drink? Not the size of the brewery as it can put out thousands of liters per hour. The real limit is how many fricken posts on CR4 cut into your beer drinking time discussing this simple subject and if you did down one or two how fast they would come back up reading my next useless post.

Current limiting:

Wouldn't the current be regulated by default if the voltage is cut off at a certain point? Maybe I'm wrong but in old generators didn't they have relay (coils and points) regulators in a box on the firewall? Didn't these coils build up a voltage (up to say 13.5volts) after the battery got "full" and then cut off (opne the points) the voltage to the field windings preventing any more power from being generated. Didn't this remain that way until such a time as the coils voltage fell below a threshold (something like 12.5 volts) and the points closed again allowing voltage to field windings which in turn allowed power to be generated into battery again?

In modern alternator I would imagine a similar situation only using solid state components instead of coils and points relays. (and also rectifier). A heavy transitor used as a switch would work in one dispensation.

Andy, thanks. As I said, I prepared and posted before there was opportunity to read everything...so I hope all understand that I was not intentionally ignoring posts which anticipated anything I said before I said it--or didn't say it. It may have been lost in the details but, although I don't doubt that I could attempt a rebuild successfully (given the time)--and that, depending on component availability, it could be the least problematic approach to obtain an exact match--I have no inclination to do so. As one post-er noted, I am beyond the youthful fervor, deprivation level, and disposable time.... By the same token, I have come to agree with those, including yourself, who suggest going the after-market route--for one, FMC does not even provide (any) replacement alternator--the generic, straight-mount ones they list are radically overpriced and, even at that, they do not fit unless I'm willing to allow a Ford service tech to make alteration. And that prospect gives me heartburn.

So I see the problem now as, basically, a systems integration problem: selecting the rebuilt least likely to have "compatibility issues" with my current battery, etc. I also seek the least labor ($ or hour) intensive...so that if clocking and such can be avoided, I would hope to do so. (By the way, I believe I have located one which could be installed straight off--you'll see about it in a post farther down.)

No, I do not take any offense at candidness when, like yours, it is not malicious--and not much then, either. Your are no doubt aware of the difference between responding en-masse to a question and trying to respond in turn to a plethora of answers. Your's and everyone's patience in understanding that no answer(er) is given short shrift by intention is appreciated.

Look, the unit is far too small for your vehicle, and I can tell without even seeing the vehicle. There're only a few vehicles that will run correctly with a 40A unit, and those will all be vehicles made before the 80s (factory specification, or without modifications).

The simplest way to determine the amount of power you need is to tally the total ampage of your fuse box. If you buy an alternator equal to your total fusebox capacity, you'll have all the power required for operations... and armed with the total ampage rating of your fusebox, you should be able to go to the dealership better able to buy according to your needs.

I've fitted alternators from different models before, but I suggest you buy the right part. Armed with this fusebox suggestion, give that a try, and perhaps you don't even need to worry about bad fitting parts, or parts with potentially the wrong capacity.

TO GUEST: "...Tally the total ampage of your fuse box."

That is probably overkill. Think of it this way: if you add 20 for cig lighter 30 for power windows, 30 for headlamps, and 30 for seat heater (luxury models), and 30 for fan for heat/air, you are already up to 110 amps without all the many little fuses.

In houses, for example there is some rule ( i forget) that is like a rule of thumb and is according to code too that says somthing like use no more than twice the main in the little fuses. I would think that you would do something similar in autos.

FYI: Make me think of bridge building. They estimate max load with bumper to bumper semis full of canned goods and then double that for load ability (to insure enough slack to prevent death when aging occurs at same time as worst case max load at same time as worst case wind shear, etc).

This is IP. This thread caught me because I was thinking at one point that, minimally, twice the highest load (typically 30A if I'm not mistaken) would give a reasonable margin: i.e., 60A or higher.

For home fuse boxes.. you are allowed to exceed the rated main breaker with the total of the many small breakers because the assumption is no one ever uses everything at once. Similarly So for cars instead of needing a 300 amp alternator.. you can use a 90 amp one and be in fine shape (unless other big loads are added on ).

There has been some excellent dialog here, and I've learned more than I care to admit about alternators. What I haven't seen is the suggestion that you check an alternator from the dealer that is either a year up or a year back from yours. I had a vehicle years ago that was built at the end of the model year - 83. whenever I bought parts, I had to get either 83 parts of 84 parts, depending on what it was. According to a friend at the time, this happens sometimes.

Good luck!

Good point. The dealer (ford catalog) lists two for a range of years going back 5 before and two afterwards. But, these are staight-in-mount, not 6:00-10:00, which means they don't fit without refit. The honest dealership I spoke to yesterday recommends that their generics (and that's essentially what they are) are way too costly, and more so if they need any reworking by an unseen "tech" of unknown ability. Because my current alternatore (and the vehicle its in) are "obsolete" (meaning, out of factory support), that dealer recommended getting a motorcraft rebuilt by others. So this is the direction I find myself heading in.

The last time I had a problem similar to this, I went to the oldest auto electrical shop in town, and the gentleman running the place answered all my questions without even looking anything up. This also happened to be a Ford truck that each dealer I called had given me a different answers.

Glad to know that approach worked for you. Unfortunately, I'm already getting the feeling of being spread a bit thin; I'll have to hold off looking for "oldest auto electric shop" if nothing in progress pans out; and, I surely haven't been in this town long enough to guess where old shops might be. I can see myself going down the same path like when I relocated years ago to Balto-D.C in Maryland. When getting directions, people kept telling me to turn where something "used to be."

Don,t know where you live but you should have a motor repair shop that should be able to repair the alternator in a day or so. In the city I live in there are a couple that specialize in DC motor and alternator repairs. They may have a rebuilt one on the shelf if the vehicle is old enough.

Ozzb,

When I live not far from you I came to realize that (except for a few Balmer area dealerships) logistical considerations (availability and quality of mechanical expertise in the rust belt; component availability, turn-around), and legal consumer protections against error and malfeasance could be more favorable that points south and west.

Another consideration is that the alternator is an a vehicle that is my mode of transportation...not surplus wheels sitting in the garage (or, as in MD, the driveway). My sources here are probably much more limited, and none are proximate to my house. If things go wrong here in Calif, your more or less on your own. This is one reason I think it's better to be armed ahead of time as much as possible. Thanks for the input.

Wow! What a huge number of posts for a simple question!

1. Yes, you can put a larger capacity alternator in to replace the damaged one. The load will draw whatever it needs. You can't go the other way though, or you will overheat the alternator.

2. Rebuild the existing one yourself. Get a re-build kit, replace the bearings, and pop in a new diode asembly. I don't do re-builds anymore though, wrecking yard alternators are too cheap.

3. I wonder if guest's problem was an overload (stalled fan motor for instance) that caused the alternator to fail, and the larger replacement capacity alternator just kept driving the load until the insulation on the wires leading up to the load melted! Just speculating, since I have seen similar snags, but of course it makes me wonder why the battery didn't do it all by itself. It has more capacity than any alternator ever made, why didn't IT burn the wires? If this was the case, the alternator was acting as a rather expensive fuse, and the snag would have to be fixed before powering up the system with a new alternator, bigger or otherwise.

There is nothing about the alternator capacity which affects the load; the load drives the system.

I have had problems with Ford Rangers with ignition wiring that would fail for no reason I could find....the fuse links (special wires made smaller on purpose that would fail before the rest of the system fails) would resemble this phenomonon. Not being there to see in person, I can only speculate, and commiserate with the poor tech who has to fix this! I would love to throttle the engineer who places fuseable links in inaccessible places!

4) When dealing with multiple power sources, wiring sizes become trickier...due to that afore mentioned Kirchoff. It is a general truism that you can never go wrong by making wires bigger, unless you accidently change out a fuse link for a heavier wire. You can't tell just by looking at the wire that it has been designed to be the "weakest link" on purpose, so I HAVE seen it done. The answer....check the manual of course!

5) I concur, "guest" seems like a pretty knowledgable person, and I would be happy to see him (or her) sign into this forum. So, please guest, consider yourself invited!

Yusef,

I still maintain that it is dangerous, if you don't know your wiring capacity, to use more amps.

~~~

I brought the vehicle with the faults and the owner wasn't able to tell me what was wrong at the time.

It took me about 1 minute to determine the fault, simply putting in a battery, turning the vehicle over and starting it, then removing the battery. boom! instant realisation. I have no idea why a fuse didn't save the day, and with no wiring diagram, I wasn't able to determine the load potential, and what ampage was rated down certain lines vital to the effected area. I know it was wire melt, which is a direct consequence of more ampage than the rated capacity, but I still don't know if pin 30 was solely responsible for the extra current draw. So that is why I can only suggest that certain wiring systems may fail under more amps.

I stripped down the alternator, checking the armature, brushes, and then had the thing tested. he confirmed that the thing was Kaput... brushes indicated about 10 years small-town-ware or about equal to the milage reading (about 2 3rds of its life)... and grooves on the armature were slight but passable. So I knew the core was Kaput... and facing a few hundred dollars to repair the thing. So I did the cheap thing, and got another from a vehicle with the same year, though it was a turbo modle. fitted perfectly, or so I thought. The vehicle was up and running, perring like a satisfied cat, and man was I buzzing out about it. I drove it around about 10 km, then went back home. It's when I went to start it the next day that the thing burnt out completely. taking about 1 or 2 seconds.. and indicated the symptoms as describe earlier.

more than that, I can't say.

~~

It's kind of a strange thing, but the alternator governs the running of the vehicle over the battery, and the battery will add to the total amps needed in the running of the vehicle.

Yeah, bigger wires handles more load, but you do eat into the total power when you make such changes... through power dissapation, though probably only a slight issue.

Thanks for the invitation... I was really just kicking around and rerouting a bit of down time. Cheers.

Smiles...there are only two variables....voltage and resistance. Amperage changes happen ONLY when one or the other of these variables change. Since you had an amperage change (a rise) take place ( no question about that!) either the voltage rose, or the resistance dropped. Or both.

If the load stays the same as usual from year to year, an amperage increase will only occur if the alternator voltage rises. The voltage would have to double, for instance, to allow twice the amperage to flow. (The formula is amperage equals voltage divided by Resistance.) I suppose it could happen if there is no battery to ballast the output, but of course, it is not supposed to do so. This, at first blush, seems to be what happened to you....voltage runaway on your alternator. But this is rare, and the fact that it happened again with a second alternator the next day blows that theory out of the water! And you said that you had it checked out, so voltage rise is not the answer. So long as the voltage output is good, you can swop out a light duty alternator for a bigger one. Won't hurt anything.

Increasing the load would reduce the resistance, thereby allowing more amps to flow. Since the voltage is pretty much held steady at 12 volts by that big old battery, chances are the load was increased on you...a short to the chassis would do that just fine. As would a fan motor which is physically kept from turning by a stick in the fan or a burnt bearing, or the installation of those big old fog lights. But the fuses are supposed to catch that, which is why I suspected the fried wires were actually "fuse links", that is wires which are designed to act as fuses.

Sometimes in old alternators, when one diode in the bridge opens, you get half wave rectification, which has a considerable lower voltage. The regulator drags it up to where it is supposed to be, but now you have voltage spikes. These spikes can be quite significant, but they won't normally result in overheating of wires, but they might play merry heck with any on board computer. But I am reaching here....who knows what voltage spikes would do to a computer! Nothing good I am sure! But to "crowbar" the ignition circuitry? Hmmmm.

The fact that swapping out the alternator resulted in a repeat of burnt wire symptoms would sort of eliminate the alternator as the problem....the real problem is whatever shorted out a wire attached to pin 30. Unless I am reading this all wrong. But I can't argue with the fact that melted insulation points directly at overcurrent. Where was that current going to? What nasty gremlin was eating all that current?

You said "It's kind of a strange thing, but the alternator governs the running of the vehicle over the battery, and the battery will add to the total amps needed in the running of the vehicle." Right on!

So, are you saying that the third alternator you put into your vehicle fixed the problem for good?

"(The formula is amperage equals voltage divided by Resistance.)"

this is the wrong light.

potential across a line into a load is the discription you have given... yet what a change of increasing altenating Ampage does is RAISE the total pow-er available E=I²R naturally, more current increases resistance potential (when the current becomes greater than its load capacity(across a wire), and therein there may be an increase in voltage even though localised) across a line and therefore the potential for wire melt.

... really though it makes sense in a sense, voltage's not truly applicable in your line of reasoning.

I'm not sure what you're talking about repeat burnt wire for? Look, it's quite simple; pin 30 is the control for swtiching current. its the feed potential into pin 30 that had changed (pin 30 has the huge operating range and is capable of drawing well above the rated current of the line that feed it)... thus I can and did conclude that this feed potential increase was due to the increase ampere of the more powerful alternator.

There's nothing wrong with the alternator, all the changes needed were wire changes to handle to increased capacity.. its really that simple.

oops...

W=I²R

sorry bout the error...

IP again. Let me add to what I just said; because you seem to be saying that a relatively high-amp consumer might constantly or intermittently be "robbing" current to starter battery, or (in the vein of secondary symptoms) to critical components such as injectors. Is this correct? It suggests to me that, before returning the car to shop for repeat diagnostics, I could try inducing a fault (turning on fan and such) to see what happens. Of course, it could still be the alternator failing to respond...to power switching...??

Did I say that wrong? The formula is Amperage equals Voltage over Resistance. Isnt that the same of what I said? I=E/R

I said...."(The formula is amperage equals voltage divided by Resistance.)

Yeah...I'll stand by that statement. Amperage is a created by voltage driving electrons through a resistance. Power is the product of Voltage times Amperage. Why is this relevant? Its not power that burns out wires, its amperage.

You strike me as knowlegable enough, and I didn't mean to undermine you in anyway

But I'm not going to repeat myself. the answer to your question of relevance is in post 69

I feel that you had intended to quote Ohm's Law, which is usually represented by V = Voltage, I = Current and R = Resistance, in the following:-

I = V/R, R = V/I or V = I X R

I have not personally seen E used in Ohm's law before, its completely new for me.

Please look at Wikipedia at :-

http://en.wikipedia.org/wiki/Ohm%27s_law

For a fuller explanation if required.

I guess there is always a first time eh! E stands for "electromotive force", which in DC circuitry is always "voltage". http://www.123exp-science.com/t/01554084787/

Be that as it may, I am done with this discussion. I stand by all my statements. The original poster will think it through, and eventually get a proper replacement alternator. Its not like old Ford engines are hard to find in the wrecking yards! And with great good luck, he will find the intermittent short which caused the problems in the first place.

Right now, I rejoice in the simple fact that all in all, its HIS problem, not mine.

Regards.

Bill

You'll see that I did realise that I posted E=I²R and in post 70 corrected that error to W=I²R. Having to point that out?

And like I said, you seem knowledgable enough, and there's nothing wrong with you line of reason.

Where as the guys speaking about the size of the pulley wheel of the alternator have gotten it completely wrong. The larger will generates greater speed than the smaller one. The larger wheel needs more torque to move it, but travels less distance compared to the smaller wheel in an effort to turn the armature an equal distance. as the drive mechanism is equal for both larger and smaller, it MUST be the larger generating more speed. That why I put the note up in here very early in this thread, a lot of the advice in here is WRONG!

nothing but C.R.A.P

Your thinking is the wrong way round!! You are thinking about a pulley mounted on say a motor or engine, this alternator is a driven pulley.

Therefore the smaller it is, the faster it turns for the same amount/distance of belt that has ridden over it.....that is being driven from a motor or engine!

Do you honestly believe that? oh well, good luck with it.

I'm not going to help you sort it out.

for a guru, you've shown very little understanding in this entire thread.

I will make one suggestion,

You need to find a formula that demonstrates the speed ratio between a driving pulley and the driven pulley, then you'll be able to come back in here a correct your mistake. forget about things like belt tension, as those only go toward efficiency, just concentrate on the speed ratio.

A simply one is if the size of the pulley on the engine and on the generator are of the same size, they are also of the same circumference and both run at the same speed, agreed?

Now if you havle the size of the pulley on the generator, it now has half the circumference, but the belt moves past at the same speed (same pulley on engine, turning at the same speed), now it must turn round twice for each turn of the motor....agreed?

Therefore the generator speed has now doubled.....

If you can't understand that, you should go for Knitting 101 at a Uni somewhere near you!!

WHAT IF I CONTINUE TO DISAGREE? in fact I do!!

Oh, well, I guess, I should take up knitting?

I love the Pullover.....!!! Well done!

Have a good one....!

Guests are NEVER Gurus, they are just "Unknown".....!!!

Some say "Unimportant" too, but not me!!! They give me so much to laugh at one way and another, so they are important (in their own way....)

Thank you kindly unknown Sir for your comments!

Not sure which 'guest' we have commenting now, (I wish all guests would sign up so we can hep those with misunderstanding better) and if you are really replying to Andy's post or just clicked 'reply' to Andy by mistake, but Andy is perfectly correct here so I don't think Andy needs help sorting that out. If anyone reading these bits of advice thinks that putting a smaller pulley on the alternator makes it turn slower than we will have some fundamental problems explaining more complex issues than this. Go look at your multi-speed bicycle if you have to or cut out little round shapes of paper having different diameters and play with ratios on your kitchen table but research this a bit before passing judgement on someone that is EXACTLY PERFECTLY 10000% CORRECT. I'm done . . . .

I thank you most kindly Sir, you are also 1000% correct.

Sorting out Guests one from the other is of course impossible for us, you would think that the ones with some sense would join us and take a name......!!!

Have a great weekend.

You really 'ort to think about it too, I am right!!! A smaller pulley on a generator causes it to revolve faster (assuming motor turns at same speed with same pulley as before!!!)

DUUUHHHH Homer......!

You are thinking about the wrong pulley, lucky 4 U, U signed on as Guest, so nobody knows WHO to laugh at!!!

Now come on andy,

I take full credit for my line of reasoning! And I received varification from oficial sources as to how rediculous I'm being. U know and I know about real time window parity.

So who's really playing the Duuuuuuhhhhh?

What are you talking about, you don't make sense - again!

Ok then andy,

perhaps you're not part of the parity club.

It looks like a good place NOT to be......!

By the way, can you be so kind as to mention to us all just how many foreign languages you speak fluently, other than Double Dutch of course!

Now how could I passup an opportunity like that?

I know "that many" foreign languages, there's really only one person able to keep up with the wirely gym (enough of the blow, more of a puff really)... its all acrobatics isn't it; and a bit of skipping from time to time. Brain Gym, Body Gym, Sensory Gym, Cognitive Gym... gees, those gymmys have been busy boys.

Just as I thought, you do have many good and valid reasons for NOT to be easily identifiable........

But at least it keeps you off the streets.....!

Do the special jackets give problems when using a PC?

I wish you a full, complete and speedy recovery.....

Yusef, this is initial post-er. You have raised some interesting points about the Ranger. I will be talking about these in a post I will place down the line: about progress with dealer diagnosis, and secondary symptoms that seem to be coming up. Hope to see you there.

Where do you live? Just take it down to the independent shop and have it bench tested. If it tests, then put it back on. If not, have it rebuilt by the independent shop. I replaced a 45 amp prestolite alternator with a 65 amp aftermarket unit on my 30 hp Universal Atomic 4 marine engine. At a higher rate the thing will cycle quicker before the regulator closes the circuit.

The core is needed by the shop or aftermarket distributor. You get an OEM that someone else brought back as a core.