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MD
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Alternators for dummies

Post by MD »

All you finger pokers out there that have a crack at "fixing" that alleged Italian bad wiring gremlin as the first mission upon acquiring an old Alfa need to know some basics.

Here is an excellent article on how alternators work and the mystery dash light..

http://alternatorparts.com/understandin ... ators.html

If you read it and don't get it, stop finger poking before you give yourself a bigger invoice to pay from someone that does.
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kevin
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Re: Alternators for dummies

Post by kevin »

MD , here is a stupid question . On my race car the alternator light is off when you switch ignition on but when you crank or car is running it is on . The battery does charge . Is it connected to the wrongs terminal on the alternator ? Can't really see so well down there but can feel another terminal .
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MD
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Re: Alternators for dummies

Post by MD »

Hi Kevin,
Can't say this reply will be definitive but basically when you turn on the ignition switch, it supplies power to the alternator windings so that it can develop some electro magnetism through the dash bulb. Once it is turning and because it has been energised by the power through the dash bulb, it will start to develop its own magnetism and produce power.Once this is in play, the light will go out as the field windings do not require power from the battery because the spinning alternator is making its own.

My simple deduction here is that your dash bulb is wired to the alternator output circuit and hence it is glowing once it is running. How your alternator is getting energised to start making power in the first place, well that's for you to finger poke and find out. :D
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Mats
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Re: Alternators for dummies

Post by Mats »

The bulb is normally wired from ignition switch on (15) to alternator output, when the the alternator produce power the voltage difference is zero and the light goes out.
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Re: Alternators for dummies

Post by kevin »

MD , I'm such a dummie as I have found out why my alternator light is on when running and off when ignition is on ( engine not running) . Problem was the edge of the bayonet fitting on alternator was touch against housing . I must have bent it by mistake when trying to put terminal on at last race day without burning my hands on the hot exhausts . I could only see problem once I got the mirror in there .
That article you posted above is excellent . If you had a choice of an alternator how many amps would you want it to be for the GTV considering you could be driving in a rainy , cold , dark winter night ( night time in UK) when you want heaters and rear windscreen on , wipers going , brights ( high beam) on as its on country roads and possibly even the radio on ( normal speakers) . So basically you're on full draw and worst case you get into a traffic jam and your fans kick in - but obviously your high beams would be off . Would you go for a 60 , 65 or 70 amp goodie . There are no extra lights in the car other than the originals .
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SimonB
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Re: Alternators for dummies

Post by SimonB »

I would go for as much as possible. My alternator light has always glowed faintly in operation over the last 16 years, even after I replaced the alternator. Battery stays charged so no problem. Lately the car stereo has begun cutting out when idling in traffic if the blower, lights, indicators etc.. are all going.

Think its new battery or alternator time soon. I saw a cool looking company in the US that rewinds and upgrades these alternators, I'll try to find a link...

http://r.ebay.com/xksLVk
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