How to Rebuild an Alternator in a car
If you are wondering what the little red light means when it
says ALT, all it is basically telling you is that the battery voltage is much
lower than the output voltage of the alternator, or it could be telling you
that the output outage on the alternator is lower than that of the battery
voltage. What you also have to take note of is if the red light gets a bit
dimmer when you start up the engine the alternator probably has a problem or
two, but if the light gets brighter, then your battery is probably going
bad.
The “brain” of the alternator is its rotor. The rotor is a
coil of wire that will be wrapped tightly around a certain iron core. The
current that runs through it is known as “field” current and it is able to
produce the needed magnetic field at the core. In order to determine the
approximate strength of the powerful magnetic field, the strength of the field
current will first have to be determined. The field current flows in direct
current which means that the current only flows in one direction, and the slip
rings and brushes are responsible for supplying the wire coil with the current.
The magnetic field that is made is just like any other magnet, as it has a
South and a North Pole direction. Even though this part is called the “rotor”,
it is actually driven by the pulley of the alternator and it rotates while the
engine runs.
The next important part of the alternator is the “stator”
and this is the part that surrounds the rotor and is actually just another
complete set of coils. This part will be found fixed to the alternator’s shell
and it is one of the parts that doesn’t turn. When the rotor rotates in the
windings of the stator, the rotors magnetic field sweeps right through the
windings and that is where the electrical current is produced within the
windings. Due to the turning motion of the rotor an irregular current is being
produced, and when the turning gesture is continued the magnetic field will be
moved to the middle of the winding where continuous coupling happens and in
turn the persuaded current will be at its peak.
At this point, when the rotation continues and gets to the
point where the magnetic field is exiting the stator winding, the current that
is induced will still be small. The South Pole will now be nearing the winding,
where it will produce a feeble current and allow it to flow in the opposite
direction. This will continue and as it does, the current that is produced in
each of the winding will be plotted against the right angle of rotary motion
of the rotor. The three separate stater winding are spaced within the
alternator each at 120 degrees apart from each other, where they produce the
three different sets of output voltages and they will do so continuously.
How Does a One-Wire Alternator in a car Work?
A one-wire alternator is self-exciting, meaning that it
turns itself on. It only requires a battery wire to be attached to the unit.
Instead of using an ignition wire to deliver a signal to the alternator, it is
replaced by a special voltage regulator that senses when the alternator should
turn on.
Inside the regulator, there is a circuit to measure the
fluctuation in the magnetic fields generated by the alternator. These
fluctuations are caused by the alternator turning, and the amount of
fluctuation predictably changes based on how fast the alternator turns. When it
reaches a certain level, the voltage regulator sends a signal to turn the
alternator on, accomplishing the function of the ignition wire from a two-wire
setup.
One-wire alternators are often used in custom automobiles,
where extra wiring can be a pain to install, as well as in nonstandard vehicles
such as tractors and riding lawnmowers. There are a few things to consider when
installing this type of alternator, the most important of which involve your engine:
Is revving your engine to activate the alternator going to be a problem, and
does it maintain a high enough RPM at idle to keep the alternator active?
Does your engine have a high enough RPM to even activate
your one-wire alternator? If it doesn’t, there are a few things you can do to
alleviate this concern. You could install a smaller pulley to gain additional
RPMs for the alternator, or you could convert it to a two-wire system by adding
an ignition wire. All one-wire alternators are compatible with a two-wire
setup, which will start the alternator as soon as the engine is running.
How to Hook Up an Alternator in a car ??
To replace an alternator on most domestic and foreign cars,
the first thing you must do is disconnect the negative cable at the battery
terminal. The reason why you must disconnect the negative battery cable is
because you may risk shorting out the new alternator or cause electrical damage
to other components of the car. After disconnecting the negative cable at the
battery terminal you must then unplug the connector from the alternator itself
(usually a round or oval plug with a rubber booth around it).
After disconnecting the accessory plug you will need to use
a wrench to disconnect the battery cable connected to the alternator. However,
you are not always able to disconnect these wires until the alternator is
unbolted. After disconnecting all wires from the alternator you will need to
loosen the belt and slide it off the pulley. You will then have to unbolt the
top and bottom bolts using a socket or flat wrench. Some vehicles have a third
bolt on the alternator bracket attaching it to the engine for extra alternator
support.
Once all of these bolts are removed, you should be able to
remove the alternator. Some force may be needed to pull it out. Disconnect
battery and or accessory wire if you weren’t able to do so earlier. Now that
you’ve got the alternator off, take the replacement alternator, inspect it to
make sure it has no defects and apply some dielectric grease over the electrical
connections to prevent corrosion or moisture damage.
Now you can install the replacement alternator and connect
the wires. Make sure that you use torque specifications for tightening the
mounting bolts. (Specifications vary by make and model). Loosen the tension and
put your belt back on the alternator pulley. Last but not least, make sure that
all wires are connected securely. Also check all fasteners to make sure that
they are tight to the right torque.
Turn the engine on and let it run for a few minutes, then
turn it off and if everything seems to be running without any problems, double
check all the fasteners one last time to make sure that all electrical
connections and mounting screws are tight. It’s better to be safe than sorry,
so the extra minutes it takes to double check everything could pay off in the
long run.
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