48Amp single phase VS 50 Amp three phase
As many of you who ride 1997 to 2005 FLH/FLT models have
discovered, they do not seem to get the stator life you may expect. For those
of you that do not know what a stator is, it is part for the charging system.
Its job is to supply electrical current to charge the battery and run
electrical devices.
In 1995 Harley
Davidson introduced its first production fuel injected motorcycle. A larger
charging system was needed to run the electric fuel pump. A 38-amp single-phase
system was developed. It was a dependable system that delivers 16 amps at 1000
rpm and 38 amps at 2500 RPM. The full dressed fuel injected models still needed
more electrical power. Instead of developing a completely new system Harley
bumped up the output of the 38-amp system by increasing the strength of the
magnets on the rotor. This is where the problems began. To make an analogy it
is kind of like taking a stock motor, boing and stroking it to the max, then
adding the most radical cam you can find. Man it really puts out but when it
hits it hits hard. All this extra power puts more stress on down stream
components. This extra stress can shorten the life span of some parts that are
not designed to handle it.
With the addition of the stronger rare earth magnets on the
rotor the system was called a 45-amp system. In 1999 with the introduction of
the twin cam motor they started calling it a 48-amp system. The 45 and 48 amp
systems are basically the same systems. This is the first system Harley made
that can produce more amperage then it is rated for. This system puts out 30
amps at 1000 RPM and about 54 amps maximum. When drawing over 45 amps out of
this system, the stator will produce heat faster than it can get rid of it. The
temperature of the stator will rise until it gets hot enough to melt the
insulation. Once the insulation burns up the stator shorts out and will no
longer work.
We spent years upgrading our stators to increase the
durability of this system. As luck will have it all of our other stators have
received the benefits from this quest.
The plastic over
molding insulation used on other stators melts at 4250 F. By 4500
they are toast. We have developed a stator that can withstand peaks of 6000F.
But Continuous operation at this temperature will shorten the stators life
span. Drawing full power out of the 48-amp system (54 amps) can result in
temperatures this high.
Another draw back to using the stronger rare earth magnets
is they produce an AC waveform that results in harsh power delivery. Alternators
produce alternating current commonly refers to as AC. If you made a graph
plotting AC voltage agenst time it would make a reciprocating wave. Ideally it
would make what is known as a sine wave. A sine wave has a rounded almost semi
circle shape to it. The more commonly used ceramic magnet rotors produce a wave
that rise and drop of more gradually. The stronger magnets used on the 48-amp
rotor produce a square output wave. This square waveform indicate a vary fast
change in voltage which leads to vary high instantaneous current. These high
instantaneous current spikes produce a lot of heat and go hard on the regulator
and battery. This is what I mean when say the 48 amp system hits hard.
Until recently there where on other charging systems
available with enough output to replace the 48 amp single phase system. The
introduction of the 50 amp three-phase system gives another option. There are
many benefits to the 50-amp system. The three main advantages are better
durability; smother power delivery and lower cost.
The larger
three-phase stator used in the 50-amp system has18 polls to do the same work of
the 12 polls on the single-phase stator. This spreads the load out over a
larger area. On top of that each poll has only two layers of wire compared to
four layers on the old stator. This will lead to better heat dissipation and
lower operating temperature.
The 50 amp three-phase system delivers a smother power
delivery for two reasons. First of all, the rotor in this system uses the
ceramic magnets. As I mentioned before they make a smother out put wave. The
second reason is the three-phase system has three sets of charging coils. These
coils produce waves that are offset 120 degrees from each other. This is kind
of like having a motor with three smaller cylinders instead of one big one.
The smaller smother more frequent waves produced by this
system delivers a smother charge.
The rare earth magnets used in the 48 amp three-phase system
are dreadfully expensive. The ceramic magnets used in the 50-amp system are
fairly inexpensive. So basically for a little more then the cost of the 48-amp
rotor you can buy the entire 50-amp system.
Due to the benefits of the three phases 50 amp system Cycle
Electric Inc. will no longer sell the 45/48 amp single-phase systems in kits.
We will continue to sell replacement parts. We do offer 50 amp upgrade kits to
fit 1998 and later.
If all you need is a
regulator or stator it is more economical to just replace that part. If you
have had chronic stator problem I would recommend upgrading to the 50-amp
system. If you need a rotor you should go with the upgrade. All things
considered, compared to the 48-amp system, the complete 50-amp kit is the way
to go.
Let the road you choose to ride bring you happiness.
Karl Fahringer
President
Cycle Electric Inc.