What is a one wire alternator?
How much amperage do I need? Amperage Load Calculator
Why does my new alternator have a smaller
pulley?
Can I use underdrive power pulleys?
Will a higher amperage alternator cause
any problems with my stock electrical system?
What modifications will I need to make
when upgrading to a high amp alternator?
What does the rated output of your
alternators mean?
What is pulley ratio? Pulley Ratio Chart
Will a high output alternator have a
shorter lifespan?
What alternators will interchange with
each other?
How do I wire an alternator
in place of a generator?
What is a one wire alternator?
A one wire alternator is used where you do not want to
have any connection from a vehicle to operate an alternator. It will
self-excite, meaning that it can start charging and stop charging all on its
own. The only connection needed for a
1-wire alternator is the output charge cable. It is most commonly used in
custom vehicles to clean up the wiring, replacing an alternator that used an external
regulator, or adding a second alternator to the vehicle.
The early GM 1-wire alternators (1972-1986) will need to
have the RPM raised to 1000 – 1200 RPM initially to get the alternator charging
and then it will continue to charge after that. The later style GM and all Ford
and other style 1-wire alternators will excite immediately when the vehicle is
started. The one wire alternators cannot be used if you want to use a dash
charging light. You would need to use the plug-in style regulator in order to
complete the circuit to operate the light.
The alternator that was provided with your vehicle should
handle all of its electrical needs as outfitted from the factory. If you have
added electrical components such as stereo amps, lights, compressors, winch,
plow, etc. then you will need to produce more power to operate these
components. Use our Amperage Load Calculator to find out how much power you now
need from an upgraded alternator.
Why does my new alternator have a smaller pulley?
Alternators produce more amperage the faster they spin up
to their maximum capacity. Most people need the best output they can get at low
speed. When the engine is idling, the alternator will not produce as much power
because it is turning slower. In order to boost output at lower RPM, it is
beneficial to spin the alternator faster by using a slightly smaller pulley to
accomplish this. In most cases you should be able to use the alternator with
the smaller pulley without having to use a smaller belt. Check to make sure
that your belt is not worn, stretched, or that the tensioner has the correct
amount of tension to keep the belt from slipping or having too much tension.
1)
Too
much load - The amount of load (components using power) may be too much for the
amount of output the alternator is capable of producing at that slower speed.
Check the amperage output at the rear of the alternator and see if it is more
or less than the amperage coming out of the battery’s positive cable. If
increasing the RPM of the engine slightly causes the alternator to exceed the
requirements, then it may be necessary to use a higher rated alternator, raise
the engine idle speed (if possible), or change to a smaller diameter pulley to
increase output at that RPM,.
2)
Idle
Speed - Some newer vehicles have idle speeds much lower than earlier models.
This is done to help the fuel economy. On these vehicles the use of a smaller
diameter pulley is almost a necessity to get low RPM output to an acceptable
level. You may find that at times the load demand may be greater than the
available output of the alternator. There is no problem with having this
condition for short periods such as heavy bass hits from the stereo. Using an
auxiliary battery to add additional reserve capacity can help alleviate
problems stemming from these circumstances.
3)
Pulley
ratio – In order for the alternator to spin fast enough to produce the power
necessary at low RPM, the pulley ratio should be correct. Changing the
crankshaft pulley or alternator pulley will vary this ratio. For most vehicles
the ratio should be at least 3:1. See the question “What is pulley ratio” to
find out how to calculate this.
4)
Wiring
– When upgrading to a high output alternator it is important to make sure that
the power can get to where it needs to go. The factory charge cable and ground
cables were designed to handle only as much amperage as the stock alternator
could provide. Using a higher amperage alternator, you need to upgrade the
charge cable to handle the higher current that will be passing through or the
power will be restricted. It is also necessary to upgrade the ground side as
well. This would include the battery to frame, body, and engine block.
Can I use underdrive power pulleys?
The use of underdrive pulleys for the crankshaft has
become popular but it has the downside of slowing alternator RPM. This will
cause the alternator to have lower output at slow speeds. We recommend that the
factory sized crankshaft pulley be used whenever you upgrade to a high output
alternator.
Will a higher amperage alternator cause any problems with
my stock electrical system?
A higher amperage alternator will not pose any problems
to the vehicle’s electrical system. Amperage will flow to only those components
that can use the energy and supply as much amperage as the component can
consume. For example, you may have a 100 amp alternator in your vehicle and the
turn signals have small wiring and will only use 10 amp of power. Upgrading to
a 200 amp alternator will not affect these components. On externally regulated
alternators you can still use the stock factory regulator. Of course you need
to get the power to where it needs to go, so see the next question about
modifications.
What modifications will I need to make when upgrading to
a high amp alternator?
Almost all of the alternators we sell are meant to be a
direct replacement for your factory alternator so you should not have to modify
the installation. You should, however, upgrade the alternator’s charging cable
and ground cables (battery to frame, body, and engine block) so that you can
get the power to where it can be used. A smaller diameter alternator pulley is
usually included with the alternator we provide and in rare instances a
slightly shorter belt may be necessary.
What does the rated output of your alternators mean?
Our alternators are tested on our test bench to provide
the best output for most driving conditions including low speed or idle
operation. The specifications you see on our website reflect results as
follows:
Advertised Idle Output @ 2,400 RPM
Advertised Maximum Output @ 4,800 – 5,200 RPM
These figures are alternator RPM speed. In order to
calculate the corresponding engine RPM you must divide those numbers by your
pulley ratio. To calculate pulley ratio, see the next question.
Pulley ratio is the comparison of the crankshaft pulley
diameter to the alternator pulley diameter. In order to get your pulley ratio
you would measure the diameter of your crankshaft pulley and divide it by the
diameter of the alternator pulley you will be using. For example, if your
crankshaft pulley is 6” in diameter and the alternator pulley is 2” in
diameter, the ratio would be 3:1 or 6 ÷ 2 = 3. The larger the ratio, the faster
the alternator will spin. CLICK HERE to
go to our pulley ratio chart.
Will a high output alternator have a shorter
lifespan?
The high output alternators we design should be able to
provide a long life. However, the more current that is produced by an
alternator, the faster the brushes may wear. If you are using an alternator
more toward its peak capacity it will tend to use more brush material. Luckily,
replacing brushes on most alternators is relatively easy and very inexpensive.
Even if you are running the alternator at peak capacity it should provide you
with years of good use before you may need to do any maintenance.
What alternators will interchange with each
other?
For GM, Ford, and Chrysler vehicles we have provided a
list of the most popular interchangeable cases to help make finding a higher
amperage alternator easier. CLICK HERE to see the list. If you do not find an option or
are unsure of which one is correct, feel free to call us at (909) 794-1600 for
assistance.
How do I wire an alternator in place of a
generator?
Since not all
vehicles are wired exactly the same the picture below is a simple example of
the wiring requirements for installing an alternator in place of a generator
system. Using the original generator regulator as a junction to connect all of
the positive wires makes it simple. You may also route the wiring in any
fashion you like as long as the power is distributed to both the battery and
the vehicle’s electrical components.
