one wire alternator

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jwm5575

one wire alternator

Post by jwm5575 »

Has anyone ever converted to a one wire alternator, and if so, how did you do it?
majicwrench

Re: one wire alternator

Post by majicwrench »

GM alternators can be made to work off just the big power wire, and it is just that simple, run one, big, wire to the back of the alternator. Not sure is that helps....
Keith
htchevyii
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Your car is a: 1982 Spider hers 1972 Spider his
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Re: one wire alternator

Post by htchevyii »

If you can figure out how to mount it, should be a piece of cake. There are a few disadvantages to one wires though. What year are you? Many have upgraded their early externaly regulated units to newer internally regulated units, including myself. There are only two extra wires, a voltage sensing wire and one for the gauge.
Link to 1 wire vs 3 wire alternators:
http://www.madelectrical.com/electrical ... wire.shtml
That being said, I have one similar to this on my Chevy Nova drag car, (I was going for minimum weight and cleanliness), and I haven't had any issues, but don't have mucch in the way of electronics, either.
http://cgi.ebay.com/ebaymotors/ws/eBayI ... 4983957497
Trey
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1982 SPIDER 2000, 1964 CHEVYII, 1969 Chevy Nova, 2005 DODGE RAM, 1988 Jeep Comanche
1972 Spider, 78 Spider rat racer 57 f-100,
So Cal Mark

Re: one wire alternator

Post by So Cal Mark »

it's very easy, and that's one reason we started providing the 95amp units. You only need the battery wire and the wire from the warning light
BEEK
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Your car is a: 1975 Spider
Location: clermont fl

Re: one wire alternator

Post by BEEK »

on my race cars, we used the bosch units, only took one wire, power to the field thru the same wire as the charging wire. but! the cutoff switch killed the entire circuit. which left the alternator dead , which is no problem, when the car was off.
probably not exactly what you are looking for, but a stock fiat unit can be used provided you install a very heavy relay unit to cut the power when in off mode. but i do agree a larger amperage alternator is definatly the way to go, as 65 amp realy is not enough for modern electronics, all we did was charge the battery, no accessories
Automotive Service Technology Instructor (34 year Fiat mechanic)
75 spider
, 6 Lancia Scorpions, 2018 Abarth Spider, 500X wifes, 500L 3 82 Zagatos. 82 spider 34k original miles, 83 pininfarina, 8 fiat spider parts cars
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baltobernie
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Your car is a: 1973 Spider [sold]
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Re: one wire alternator

Post by baltobernie »

You can use the 55 or 65A Bosch alternators from later model Spiders with little modification. If you'll Search this topic, I think the consensus is that 55-65A is adequate for stock applications. People often attribute dim lights or slow wipers to alternator output, but the culprit is more likely bad wiring. Of course, if you've got a big stereo, extra lights, etc. then you need more juice.

I rigged mine by running the exciter (small) wire thru the charge indicator lamp, and from there to a switched ignition source. There must be some sort of voltage dropping item between the charging wire and the 12v buss. The regulator regulates by comparing the voltage present on the exciter wire to the big output wire. If the two are equal, the alternator will run wide open (15-16v). Brighter minds than mine have calculated the resistance value required for various installations, but I've found that the tiny charge indicator lamp in the tach is enough for my purposes. My car has shown such consistent 13v under various loads that I donated the voltmeter and reinstalled the clock! Once the engine reaches 1200 RPM for the first time, the lamp stays off entirely.

The downside of the "idiot light" is that you must ensure that it is operational every time you start the car, by pausing briefly between On and Start. If the lamp is missing or faulty, your unregulated alternator will fry the car's lights and accessories and ultimately fail ... and you will have no indication that this is happening.
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