1-Wire Alternator

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chimpvalet
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1-Wire Alternator

Post by chimpvalet »

Went looking for a compact alternator to upgrade my sportscar under restoration, came up with a Delco-Remy that fits the installation nicely. I believe it's a CS-121 type and is a 1-wire configuration, unlike the OEM piece. Given that I'm upgrading the wiring system extensively, including additional fusing, relays, grounds and feeds what, if any, would be reasons for concern on use of the 1-wire type?
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Re: 1-Wire Alternator

Post by hoodeng »

A one wire alternator is internally regulated, a multiple wire alternator is externally regulated.Go with the one wire if that will do what you need.
If you are going for detail in a restoration you would replicate the OEM, including the type of alternator and regulator and its associated loom.

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Re: 1-Wire Alternator

Post by BOOT »

Some aftermarket alts are either I think, I wanna say the last one that I got was 1 wire capable but I use it with the factory harness and works like a normal alt.
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Re: 1-Wire Alternator

Post by BCjohnny »

One wire alternators were originally designed for industrial & plant applications where there was no facility, or need, for an 'idiot light' to monitor the charge/no charge condition

There is no 'pre excitation' of the rotor coil, they use an internal circuit within the regulator to count residual magnet rotor pole pulses and, when sensed from a rotating engine, switch on the rotor field to power up the alternator

If you have a voltage gauge, then consider one wire, if not you'll never know if it's charging or not ...... personally I'm not keen on them, although they do make wiring and install clean, hence adoption by the aftermarket crowd

The 'residual magnetism' component is the key, relating to time since last charging and rpm mainly, but also tolerances, so without a voltage gauge on a 'one wire' you just don't know

As regards 'multiple wire' alternators they can be either external or internally regulated ...... it has nothing to do with the number of wires ...... so you really need to confirm what you actually have before blowing it up
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Re: 1-Wire Alternator

Post by hoodeng »

What i should have identified, if it originally had an early three wire alternator was the marking of the terminals, as in, B = battery or to ammeter if installed, F = field, N/S neutral or star= warning light operation, early alternators typically had external voltage regulators regardless of their application
As the op said it was a restoration, i was thinking early.
On some of the early plant that i worked on there would be the usual array of instruments, there was also a bank of warning lights and buzzers that would all go off when the battery key was inserted, when the engine fired and everything came on line, lights and buzzers would extinguish.

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Re: 1-Wire Alternator

Post by chimpvalet »

Thanks for the advice, all welcome. The car has a voltmeter in the dash cluster, as the vendor was careful to inquire on. Seems I'll be OK with the 1-wire as long as the system is well put together.
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Re: 1-Wire Alternator

Post by BCjohnny »

hoodeng wrote:B = battery or to ammeter if installed
Yes, but you you need to establish B+ or B- with 'early' designs
F = field
Yes, but if you don't know otherwise you need to establish field to positive or field to negative switching, and whether the field is internally driven from a bridge or externally via an ignition feed
N/S neutral or star = warning light operation
Sometimes, although rarely directly, often through a 3AW (Lucas) or similar

It can also drive a tacho, carb choke ..... or anything that needs AC only when the engine is running, not permanent or switched DC

And although most early ones were 'star', many later ones were 'delta', not that changes much in itself
early alternators typically had external voltage regulators regardless of their application
Yes, almost exclusively amongst 1st gen designs, but although it lingered on in US and Japanese thinking it was gone in less than a decade amongst the better European machines
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Re: 1-Wire Alternator

Post by hoodeng »

As the term used by chimpvalet was 'restoration' for his project, i should have first asked the obvious. Make, Model, Year.

I 'assumed', and we all know what that stands for.

Electrical symbol nomenclature runs pages.

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Re: 1-Wire Alternator

Post by BCjohnny »

My above post, while only skimming the surface of a very involved subject, is slightly more than 'electrical symbol nomenclature' :wink:

Although it may help point someone in the right direction with their 'restoration project' if they get stymied ......
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