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Discussion Starter #1
Hello,

well loks like I won't be getting that $200 windshield. so I'm on to my next project - Until I get a cheap windshield.

I'm going to change the alternator brushes and diode, just ordered it from IAP.
I read on this site http://forums.vwvortex.com/zerothread?id=3477781&postid=42503442 that you can raise the output voltage by .6 volts by installing a diode backwards (.6 is the voltage drop of a diode).

I understand (electronically ) how it's done and I was wondering if any of you have done it.

Naturally I will get a bigger alternator to distribution box cable, as well.
 

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1966-2013
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I took the easier route and just got the adjustable regulator from them.

Direct install, then the turn of a screw on the back to make the output voltage go up or down as you desire.

You get .6 volts with a diode, I got over 2 volts with the screw :shrug: (I backed it down so it runs around 14-14.3 at idle, but had it as high as 15+ just to see what the upper limit was)
 

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Yeas but that would be too simple. :)
 

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Messing with the diode polarity strikes me as a bad idea. The people who designed these things weren't fools, batteries don't like being overcharged (well, no one likes being overcharged!), and lastly, I'm puzzled by why you think that more voltage will somehow make your life better. Sort of like why do some car enthusiasts (not WopJob) think that larger diameter wheels or bigger tail pipes are better?

Yea, I read the thread at vwvortex.com, and still don't see any rational explanation as to 1) why this wouldn't impact reliability, or 2) what the benefits are.
 

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1966-2013
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I'm puzzled by why you think that more voltage will somehow make your life better.

LOL

You haven't been stuck out with your headlights no brighter than candles, your wipers moving at about 2 beats a minute, the defroster fan struggling along and only able to blow hard enough to clear a patch of windsheild about the size of the palm of your hand, along with the ignition and ECU faltering due to all the voltage draw enough times, have ya :) (quick, which 2 do you turn off to get enough voltage free'd up to get you home?)


Really, the L-jet system is a pretty horrific draw on the electrical system in general, and everything else suffers because of it.
 

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volt's are one thing,, but to drive the needs of your car....AMPS.. are what you need.:)
 

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Bianchi I hope this does not led to a which is better Volts vs Amps thread! LOL....

Please note that raising the volts may shorten the life of your lamps!

I feel that one undiscussed "improvement" is a better main ground strap from motor to body. I am working on an improved design and lower resistance (read that as volts drop).

The main improvement is increasing the size of the RED output wire from the alternator (or paralelling it with a second flexible red wire).

To my mind, it is much easier to have your alternator "rebuilt" by your local electrauto shop and have the voltage regulator upgraded more Amps. ($50.. with bearings!)

ttfn Elio
 

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I feel that one undiscussed "improvement" is a better main ground strap from motor to body. I am working on an improved design and lower resistance (read that as volts drop)
True, you can never have too many chassis grounds on the engine.

I use a big bore battery cable that jumps from one side of the engine mount to the other over the rubber bit on both sides. Takes about 6-8 inches per mount and is far better than the strap affair.


On volts and bulb longevity:

I've not had bulb one burn out since I upped the output, but then again I kept it within the spec called for in the manual. (just the high end of it :) )

Actually had more trouble keeping bullet fuses in it as they liked to vibrate loose then begin to arc in conjunction with the voltage heating up the 20 odd year old spring contacts.

A fellow BB'er gave me oppertunity to get hands on the more modern minifuse type panel (straight over swap with no difficulties what so ever, including the cover as found on the pre-85's) and life has been very good ever since. That alone was worth better than 1/2V under full load. (everything turned on that could be turned on at idle)


Edit:

That would be on a 65 amp alternator BTW.
 

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FWIW, I had a VR go bad, and as it put out just under 17V it blew practically every bulb in my S3 Spider. IIRC, there are something like 23 bulbs in the dash pod alone! Not fun.
 

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Tifosi had written: "You haven't been stuck out with your headlights no brighter than candles, your wipers moving at about 2 beats a minute, the defroster fan struggling along and only able to blow hard enough to clear a patch of windsheild about the size of the palm of your hand...."

Of course I've had these problems. Anyone who has owned an older car has dealt with electrical gremlins, and yes, they can be annoying. What I am saying is that when your car has these symptoms, raising the alternator output by .6 volt is unlikely to make much difference. As others have written, fixing corroded grounds, repairing those &^%$#% Bosch "pointy" fuses, and correcting loose connections is more likely to resolve things.

Certainly when these cars were new, they didn't have "headlights no brighter than candles", or "wipers moving at about 2 beats a minute." Yet, their alternator diodes were installed with the right polarity. If your car needs maintenance, some quickie fix isn't going to substitute for correcting the real problem.
 

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Raisin voltage?

I remember in elementary school we got voltage out of a potato, but I didn't know you could do it with a raisin...

(ducks)

-Jason
 

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If your car needs maintenance, some quickie fix isn't going to substitute for correcting the real problem.
Never said it would ;)

Though I'd never try something like reversing diodes especially since it's a DC system.

It just doesn't seem 'electrically correct' to me, but the adjustable regulator did as I'd used them before on previous vehicles of various types and makes. (a potentiometer to adjust the output, or rather resistance to the output, is basically all it is)

I'm still convinced the L-jet is one of the more electrically piggish systems though, and wouldn't be surprised in the least if even when spanking new the accessories started slowing down or dimming when they were all turned on at once. (the thing needs 10.3-10.5 volts all by itself just to turn on, and if voltage drops to low 11's once it's running you get all those sexy misses and pops, then once you start turning other stuff on, the load can easily exceed alternator output in a hurry)

Look at the number of folks the glowing generator light when all they do is turn on the headlights and blower motor or wipers. That in itself is indicating the voltage draw is working the heck out of the alternator while it tries to keep the battery push 12V. (that light starts to glow at around 12.1 and really gets bright at around 11.5 and down)

IMO in stock form the Alfa electrical systems in the S3's aren't the most efficient by a long shot (just looking at schematics you can see it screams piggyback add-on to the original 60's or 70's harness) and anything that can be done to reduce resistance like headlight, starter and coil relays, and/or improve the recharging circut with bigger amp or adjustable regulator output, the better.
 

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Discussion Starter #13
I found this solution while searching for a regulator for my alternator. there are some symptoms in my charging system that come and go. The car runs file and always starts. Every so ofter I have to step on the gas soon after I start the car for the volt meter to "register" also the voltage goes really low when the AC, blower and light are all on, during a rain storm for example.

It's time for me to change the regulator I believe. I already cleaned all the negative grounds I see. This will be a good time to update to a bigger positive cable.

I was not talking about reversing the voltage regulator diode(s), but adding a diode to the reference voltage. for those of you who know electronics, diodes causes a .6V drop when reversed. this is for the reference voltage for the regulator "fooling" it to think that the voltage is .6V lower than it really is and thus the regulator increases its output voltage by .6V. A resisitor, instead of a diode will not work for reasons that are beyond the scope of this post.

It is possible that the 20 year old A/C motor is now drawing more current that when it was new, and eventually it will have to be R&R as well.
 

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Ahh, I get it.

Still, having to blip the throttle to get the light to go out (non-voltmeter types) after startup seems relatively common in many systems I've been exposed to over the years.

It's more a result of the startup RPMs being lower than the 'start charging' threashold of the alternator.

EG; if you crank and fire without touching the throttle and the revs never go above, say 900, during that process yet the alternator (or rather regulator) doesn't activate the first time til 1100 rpm, then it won't actually 'turn on' (and turn the light off) until the first time 1100 rpms is achieved by blipping the throttle.

Once it's 'turned on' it stays on 'til the engine is shut down.

At least that's always been my understanding of it.
 

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Actually a diode is about .6 volts when in the foreward direction. reversed they dont conduct(except zenner diodes) till they are destroyed.
it would be better to trace the voltage drops under load to correct the problem, sinc a bad connection might go completely bad and leave you stranded.
cliff
 

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Excerpt from a link found in the electrical section as supplied by robtechno and relative to the alternator output and the glowing dash light light til you rap the throttle:

In the Bosch system, the size of the charge warning lamp bulb is critical. Too low a wattage bulb will not supply enough field current for "bootstrap" operation to be reliable. The Bosch book that I have states that the lamps must be at least 2 watts for 12 volt systems. If you have replaced your charge warning lamp recently, then too small a lamp may be your culprit.
As in a 1.x watt bulb will all but force the throttle blip to wake up the alternator and kill the light.

The full article in case you're interested.
 

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.. i just stuffed a ford alt. into my car..it's of a 1.9 liter car, and it will put out 95 amps of power..and my lights are very bright, and the wipers work really well..no slowing...go to the 'seacrh' type in ford alt.
 
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