One-Wire Alternator Conversion
Article by Mark Trotta
Many hot rod and street rod builders install one-wire alternators because it keeps things clean and uncluttered under the hood. They're also popular with engine swaps, race cars, and just about anything else you want to put one in!
One-wire alternators are also a good choice when converting an old car or truck from 6-volts to 12-volts. They are often used to replace generators in old trucks and farm machines.
One-wire alternators are small, inexpensive and very easy to wire in. They'll also do away with an external voltage regulator, as they have a built-in internal regulator.
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Delco 10SI Alternator
The majority of one-wire alternators are based on the old GM Delco 10-SI unit. These were first seen on 1969 Corvettes, and were one of the first internally-regulated units.
Compared to the externally regulated units they replaced, the 10-SI alternators proved to be more reliable with less clutter. Even by today's standards, they provide a good amount of output (up to 100 amps), and work equally well at low RPM and idle speed.
Delco 12-SI Alternator
The 12-SI alternator was introduced in 1983, and shares the same basic dimensions as the 10-SI unit. It's two primary advantages over the 10-SI are better cooling capacity and higher amperage.
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Chrome One-Wire Alternator
This beautiful 100-amp unit is sold by PowerMaster, and can be wired conventionally (3 wire) or with one wire. The one-groove pulley is also chrome.
Shop: PowerMaster 17294 Alternator
If you're needing more amperage, PowerMaster also offers a non-chrome, 150 amp, 12-SI unit. Like the 10-SI, it can be wired conventionally (3 wire) or with one wire. The pulley accepts a single V-belt.
Shop: Powermaster 57294 Alternator
PowerMaster products are proudly made in the USA.
Installation
Hooking up a 1-wire alternator is simple. The only wire needed is the "charge" wire, which goes from a terminal on the alternator to a positive battery source. This can be the starter relay, or any positive battery source.
For those who are upgrading from an external voltage regulator setup, once the new unit is installed, you can either remove the extra wires and voltage regulator from the firewall or just leave them in place.
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Conversion Kit
For those willing to disassemble and reassemble, Summit Racing offers a one-wire alternator conversion kit.
This kit converts GM Delcotron 10-SI Alternators to a one-wire unit.
Detailed installation instructions can be seen here.
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Notes and Misc
A one-wire alternator does not permit the use of a charge warning (idiot) light.
Correct Wire Size
The higher the output is, the heavier wire is needed.
For 75 Amps - 10 gauge
For 100 Amps - 8 gauge
For 150 Amps - 6 gauge
For 200 Amps - 4 gauge
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