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HomeTips & GuidesSingle Wire GM Alternator – Everything You Need to Know

Single Wire GM Alternator – Everything You Need to Know

If you seek to upgrade your alternator, there is no better way to do it than to use a single-wire GM alternator. 

While this one-wire alternator was originally meant for heavy machinery, it’s available for any engine or drive system today. 

After all, it offers a simple and clean installation, plus enough power and a built-in regulator. 

Read on to get all the information about a Singl-wire GM alternator, including its installation and grounding.

What Gauge Wire for One Wire Alternator Installation?

When using a one-wire alternator, the wire gauge typically depends on the alternator output in amperage.

If the alternator output in amperage is large, the wire gauge size must be bigger ( larger diameter). 

For instance, a standard one-wire alternator with an output of 55 to 65 amps requires a wire of gauge 8.

 For 65 to 100 amps alternator load output, you will need a larger wire gauge of 6. On the other hand, for any alternator output above 100 amps, you must use 4 gauge wire. 

Note that the smaller the numeric value for the gauge, the higher the gauge size and the better the wire. 

Using the right wire maximizes the alternator’s capability while reducing the risk of cable burning.

 In addition, the wire gauge recommendations highlighted above are for hood-mounted batteries with a 7-ft or less charging wire. 

If using batteries mounted on the trunk, a 2-gauge wire is the minimum since the charging cable is more than 7ft. 

However, if your alternator amperage is 100-amp and above here, I recommend using 1- 0 gauge wire.

A micrometer to measure wire gauge

A micrometer to measure wire gauge

Does A One Wire Alternator Need to Be Grounded?

As you know, grounding completes the circuit in all car accessories. For this reason, a one-wire alternator needs grounding, too, to function properly. 

Usually, its grounding is through its housing to the engine block or the mounting brackets. However, the chrome finish or the paint may prevent effective grounding.

 Therefore, connect a grounding strap from the casing to the car frame or the negative battery terminal.

 Doing so ensures a quality grounding that makes the single-wire alternator perform as intended.

Does A One Wire Alternator Need a Voltage Regulator?

No. The one-wired alternator has an inbuilt self-regulating mechanism that regulates its voltage, eliminating the need for an external regulator. 

The sensor in this automated mechanism senses a certain engine rpm threshold and starts charging the battery automatically. 

Usually, this rpm threshold is 1200, but some models sense even lower engine rpm. 

Something else to note is that slowing the pulley ratio prevents the alternator’s automatic regulator. Again, it causes low voltage when running at idle engine speed.

 Therefore, keeping the pulley ratio at the recommended 3:1 is vital for optimal efficiency.

An image of a voltage regulator

An image of a voltage regulator

How to Wire a One-Wire Alternator

What interests most users about the one-wire alternator is its ease of installation and wiring. This device does not need numerous wires connecting to external and internal regulators.

 You just need one wire which you connect to the alternator charging terminals. 

Then the other end, you hook to the positive battery terminal or any positive connector junction such as the start or solenoid

You can ground the casing to the car frame from there, as discussed above. 

Note that if you are wiring a car that has an external regulator, you must remove the former wring at the regulator. 

Then, you can easily hook the one-wired alternator without requiring OE cables. However, note that if your car has an indicator light, it will not work after the installation. 

You should install a voltmeter on the dashboard to help monitor your battery and its charging components.

 Last, be aware that this type of wiring is mostly useful when doing a complete rewiring on your car.

A technician wiring an alternator

A technician wiring an alternator

Will A Higher Amperage Alternator Hurt My Car?

A higher amp alternator will never hurt your car. If your alternator output is very low, all your car devices will not have enough power. 

Since they always need power, they will use the stored charge in your battery, which drains it fast. 

The battery should be for starting the car only and usage when the engine is off. 

Most engineers recommend an alternator with about 25% more power than your requirement. 

To get this value, you must add the amperage needs of all your components. 

You can get the rating for each device from your manufacturer’s manual or website. While this may not hurt your car, you need a large charge cable. 

The cable plus this high-output alternator can also be expensive, yet you do not need power.

Wrap Up

Now, you have all the information you need to upgrade your car with a single-wire alternator. 

Amazingly, it is easy to install, offering a clean one-wire mounting and provides enough power depending on its rating.

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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