charging system of virtually any vehicle consists of the power
generation source, a storage device for electricity and some
sort of controller to maintain system voltage within preset
limits. The purpose of this short article is to outline in simple
terms the function of the system and to identify its parts.
The article is not intended to be in depth on and has been written
without proof but with the hope that it will be useful to someone.
order to provide power for functions such as the ignition system
(spark to ignite the air-fuel mixture), an electric starting
motor (often referred to as a “starter”), lights,
and other accessories the typical motorcycle system consists
of a battery which is used to provide power when the engine
is not running, to supplement power when the charging system
is not providing sufficient output such as at idle, and often
to act as a buffer to help keep system voltage more uniform.
the KLR uses a separate system to generate power for the ignition
the charging system, the battery simply acts like a tank or
reservoir to store electricity until needed. Like a tank it
has a limited capacity and will run “dry” if more
comes out than goes in for a long enough interval of time. A
bigger capacity battery will hold more power, take longer to
drain at the same load, take more space and be heavier. A larger
battery will also take longer to charge on the same charging
we are talking at basic, basic level.
time and energy allow I will try to deal with each of the components
in greater detail.
battery of course will eventually empty (go dead) if there is
not some means of refilling the electricity that is used and
that is the function of the power generation part of the system.
In most modern applications the power generator is referred
to as an “alternator”. Alternator because, unlike
systems of the 1960’s and before, the alternator generates
alternating current (AC like house power) which is changed (rectified)
to direct current (DC like from flash light batteries). More
on DC and AC current later.
alternator is usually mounted internally to the engine on motorcycles
and externally (belt driven) on automobiles. That whine which
usually gradually diminishes when you start the cage in the
morning is the sound of the alternator working hard to recharge
the battery, replacing the power removed in starting the engine.
other members of the charging system “team” are
the rectifier and the regulator. In simple terms the rectifier
uses diodes (electrical one-way valves) to change alternating
current (back and forth) electricity to direct (one way) electricity.
More on these later.
rectifiers are inside the alternator however small charging
systems such as those on most motorcycles have the rectifier
mounted somewhere where a reasonable amount of airflow can provide
cooling for the rectifier. Rectifiers such as the KLR’s
are 3 or 4 inches square by about 1 inch thick and typically
have fins to help dissipate heat.
final component of the charging system is the regulator that
is really a misnomer because it doesn’t really regulate
at all. What it does is to limit the maximum voltage that the
charging system produces. Under typical circumstances it operates
to prevent the charging system from pushing the system too voltage
too high and frying things. Most motorcycle voltage regulators
are mounted together with the rectifier.
of us who grew up with 1960’s motorcycles will remember
characteristics of very simple charging systems. Many of these
early bikes had not regulator and simply matched the alternator’s
capacity to the load. This meant that the lights and any other
loads were sufficient to prevent the alternator from pushing
the system voltage too high. If the headlight bulb burned out
the voltage would start to climb and burn out the tail light.
of the old British bikes were even more interesting. The twins
would take brake light power from the ignition power for one
cylinder, which meant that the engine would miss when the brake
was applied. Typical British logic justified this by saying
that you weren’t meant to accelerate with the brake on
articles will deal with subjects such as amps, volts, resistance,
charging system testing. Starting system, and so on. Please
keep in mind that I operate a business, try to spend time with
my family and have a new KLR sitting in the garage. So why are
you doing this instead of riding, you ask? Good question! That’s
why these articles are not proof read- no time. Please help
out and spot errors or better- write some (articles that is.
intent is simply to try to be of service. Hope something is