solid state voltage regulator is specifically designed to fit Splitdorf DU model
generators, including DU-1, DU-5 and DU-7 both clockwise and counterclockwise
rotation. These generators were commonly used on Indian, Henderson, Excelsior
and other motorcycles (except Harley Davidson) from 1918-1931.
The basic circuit design is
similar to that of a modern automotive voltage regulator. All internal solid
state components are sized specifically for this application and are designed
with a minimum 100% overrated safety factor. The regulator components are
assembled onto a printed circuit board which is then housed inside a brass cap,
and encapsulated in a high temperature epoxy potting compound which is
impervious to water, oil or dirt and insulates the components from vibration.
Four clearly labeled and color coded wires with terminals allow for easy and
positive electrical connections.
After installation of the
Splitdorf Solid State Voltage Regulator on a properly functioning Splitdorf DU
series generator, the charging rate will be variable and automatic based on
demand, and limited only by the design and condition of the generator. This
will eliminate the annoying problem of either overcharging or undercharging of
the battery, and the guesswork needed when adjusting the third brush to change
the charge rate.
The original Splitdorf
generator design required removing the cap and adjusting the position of the
third brush in order to change the charging rate. By moving the third
brush in relation to the + or Ė brush (depending on rotation), the voltage
applied to the field windings was changed. This in turn changed the strength of
the magnetic field applied to the rotating armature and thus limited the maximum
charging rate, or current output, of the generator. The generator would
continue to charge at this rate all the time, regardless if the battery
were boiling over or dead, lights on or off, it didnít matter (see the DU-5
Three Brush curve in the graph at the end of this section). Many batteries and
fine paint jobs have suffered from this poor regulating system!
The Splitdorf Solid State
Voltage Regulator requires removal of the third brush and the often troublesome
cutout relay. This will allow the solid
state voltage regulator to accurately control the
voltage to the + side of the field windings, which will in turn control the
current output of the generator. Based on the battery voltage, the generator
can now charge only as much as needed. When the lights go on, generator output
increases in an effort to maintain the desired battery voltage. When the lights
go off, the charge rate tapers down as the desired battery voltage is obtained,
then a small trickle charge is applied to maintain the battery. If the battery
is low, a high charge rate will be seen until the desired battery voltage or
state of charge is obtained, at which point the charge rate tapers down to a
trickle charge. Depending on the condition and size of the battery, this may
take some time, as the maximum output of the Splitdorf generator is rather
modest. See the graph at right.
Installation can be performed by the average Joe, even
one who may be electrically challenged! The original cutout assembly and third
brush must be removed from the generator. Depending on rotation, some generators
will require reconfiguring the internal field wire connections. The solid state
regulator fits neatly inside the cap of all DU series generators and is held in
place with high temp RTV silicone. It is impossible to detect the regulator
from the outside. Detailed installation instructions, all necessary hardware
and a small packet of heat conducting paste are included. Only the small amount
of high temp RTV silicone is not included.
In developing this
regulator, numerous prototype regulators were thoroughly tested in a series of
extreme conditions on a test stand, including prolonged overload and
over-temperature tests and every conceivable improperly connected situation was
attempted. The only damage to a generator during testing occurred as a result
of a 3 hour full load (6 amp) test while maintaining an ambient temperature of
180 degrees F around the generator. The generator failed due to excessive heat,
but the regulator was removed and installed on a second unit and worked
Prototypes have also been
running on a variety of machines since May of 2004. All prototypes have
performed very well, with no failures to any regulators, generators or batteries
as a result of installing this regulator.
Every regulator assembly is
individually tested at full and no load conditions prior to shipment.
INSTALLATION WILL REQUIRE THE FOLLOWING: