FAQ, Frequently Asked Questions 

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     Table of Contents

  1. How does an alternator work?
  2. Do I need a larger Battery wire to the Alternator?
  3. What is a Self Exciting (One-wire) Alternator?
  4. Do I need a high amp voltage regulator when using a high output alternator?
  5. I need more power at Idle
  6. When is ... ?

 

 


 

Understanding alternators
How does an alternator work?
 

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Do I need a Bigger Battery wire to the Alternator?

When upgrading to a higher output alternator you should always install a larger wire between the alternator and  battery. Even with a standard output alternator you will get better performance and life out of your alternator if you upgrade the main battery wiring. The original wire just isn't large enough for proper power transfer. 
If you are using your alternator to it's maximum output or when you upgrade to a higher output Alternator you must increase the wires size. An alternators ability to send the power it is making to the battery is directly related to the wire size and quality of connection between the alternator and battery.
 Also, a wire that is to small when used on a high output alternator can cause the power to back up within the alternator making it overheat, burn up and fail. 

Another area that little is paid attention to is the ground. You must also improve the ground as well. A poor ground will hinder the alternators ability to send power to the battery and can burn an alternator up just as fast as an inadequate alternator to battery wire. Your ground may be fine when you first install your alternator but over time corrosion and resistance builds up in the ground connections. This is why it is best to run the ground directly from the rear of the alternator to the battery.

Here is another great auto electric tip from Randy DuBois on upgrading the wire between the alternator and battery. Randy says, you do not need to rip out your old wiring when upgrading. You can piggy back a second wire between the alternator and battery. The main battery wire connected to the back of the alternator has power to it at all times, even when the vehicle is shut off.  You connect this wire like normal then you run a second wire between the alternator and battery. The power coming out of the alternator will treat the two wires as one, power follows the path of least resistance. 

On a safety note when running the second wire you should fuse it near the battery. The fuse is just in case the wire gets pinched or shorted out, the fuse will blow instead of the wire burning up. You should use the largest fuse you can for the wire size, fuses are restrictive to current flow.

 

 

copyright ? 2001, National Quick Start Sales All rights reserved. Quick Start, Quick Start Rebuild Kits and Quick Start Truck & Auto Electric Products are  trademarks of National Quick Start Sales, Delco-Remy is a trade mark of General Motors Corporation

 

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What is a Self Exciting One-wire Alternator?

A self exciting or "One wire" alternator as it some times called, has only one wire running to it., that one wire is the main large battery wire. Don't confuse one wire because the plug going to the alternator only has one wire to it, this is a two wire system. The one wire, self exciting alternator that uses a special voltage regulator that doesn't need an ignition wire to activate it. 
This type alternator only requires a battery wire hooked to it. The voltage regulator contains 
circuitry that uses the residual magnetism in the alternators fields to determine when 
to turn the alternator on, the regulator does this by sensing the RPM the alternator is turning. 
When the alternator gets to a certain rpm the voltage regulator "turns on". Typically you start
the vehicle, rev the motor slightly then the alternator starts charging. This type alternator is 
commonly used on custom cars & trucks, tractors and other non standard applications when
wiring is a factor. In choosing this type alternator you must consider, do you want 
to rev your motor slightly to get the alternator to turn on. Also when using the self-exciting 
alternator on tractors or other slow turning motors does the engine 
have enough RPM's to start the alternator charging. This can be overcome by using a smaller 
pulley or by adding an ignition wire. Is another name for the Self-Exciting Alternator mentioned above. You only need connect the battery wire (one-wire).

Two-wire
Alternator:
Most standard and all self-exciting regulator alternators will work using the two wire setup. Two wire means that you use the battery wire and an ignition wire to activate the alternator. With this setup the alternator starts charging as soon as the engine is running

Three-wire Alternator:
This setup uses a battery wire, ignition/warning light wire and voltage sensing wire, Three wires.

 

copyright ? 2001, National Quick Start Sales. All rights reserved. Quick Start and Quick Start Rebuild Kits  trademark of National Quick Start Sales, Delco-Remy is a trade mark of General Motors Corporation

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Do I need to change my voltage regulator when using a high output alternator?

When you upgrade your existing alternator you shouldn't need to upgrade your 
voltage regulator. When upgrading to a high output alternator you rarely need 
to change your voltage regulator. The voltage regulator controls the alternator
output by sending power to the rotor (field). The rotor spins inside of the stator,
the reaction between the rotor & stator is how power is induced within the stator. 
The voltage regulator senses the battery voltage, if the battery needs more power 
the voltage regulator sends power to the rotor coil turning the alternator on. If the 
regulator senses that the battery or system needs a lot of power it sends maximum 
voltage to the rotor making it a big electro magnet thus causing the alternator to produce 
maximum power. If the regulator senses a small need at the battery it will send minimal 
power to the rotor causing the alternator to produce little power. Never 
does the alternators amperage go thought the voltage regulator. The area of 
concern when changing to a high output alternator is the amperage draw of the 
rotor. The voltage regulator does have a field amperage rating and because it 
has direct contact with the rotor you must be concerned with the amperage draw 
of the rotor. If the amperage draw of the rotor is greater than the rating for the 
voltage regulator the regulator will fail.

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I need more power at Idle

There are several ways to get more power at lower engine speeds. If you only require a little more power at lower engine speeds you may be able to use a smaller pulley. The smaller pulley turns the alternator faster at lower speeds thus making more power. When using a smaller pulley care should be taken not to over rev the motor. If you over rev the alternator with a smaller pulley the alternator can fail.

The best way by far to obtain more power at lower engine speeds is to install an oversize alternator. The physically larger alternators produce more power at lower engine speeds and are much more reliable at higher outputs. 
Installing a higher output alternator that is the same size as your original alternator will not give you more power at idle. 

 

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