Charging Systems

 

     The charging system is what replenishes used or depleted voltage at the battery.

     Most automobiles use a battery to operate electrical components when the engine is not running and to start the engine. After the engine is started the electrical components and systems operate using power from the charging system  or alternator. Therefore, if you disconnect a battery cable from an automobile while the engine is running, the engine and electrical systems will continue to operate.
     Harley-Davidsons operate completely off of the battery and the charging system simply replaces the voltage at the battery as it is used. If you disconnect a battery cable while a Harley is running - everything stops!

For a quick check to see if your charging system is working correctly, simply connect a volt meter to the positive and negative posts on the battery. With the engine running at 2000RPM you should read more than 14 VDC and not more than 14.5 VDC.

 

     In General, a Harley-Davidson's charging system is made up of only three components (not counting wires). The Stator, Regulator/Rectifier and the Battery.

 

     Stator
     Several windings of copper wire coiled around an iron core mounted to the engine case (left side) with a magnetic 'Rotor' splined to the sprocket shaft. The plug exits at the left front of the engine case.
     Test the stator for continuity, check to be sure it's not grounded, test A/C voltage and amperage output. Inspect the rotor for signs of rubbing on the engine case or stator wiring and for any loose, cracked or broken magnets. When replacing the stator, the four mounting bolts should always be replaced. If that is not possible be sure to clean and loctite the four bolts holding it to the engine case.

 

     Regulator/Rectifier
     A solid state unit (mid 1970s and later) with cooling fins on the top. It is Usually mounted near the front of the frame
 or engine. Grounded to the frame or engine, plugged in to the Stator plug at the 
      left front of the engine case with a long wire to the 'Main' breaker or the battery.
There is no true way of testing the regulator other than replacement. Plugging or unplugging the regulator while the motor is running can cause an electrical spike and short out the regulator.

 These things are easy to smoke. Just a little too much amperage and that's all she wrote.

 

     Battery
     Chemically activated electrical storage unit.

     Lead Acid Battery
     Invented in 1859 by French physicist Gaston Planté, are a type of galvanic cell and are the most commonly used rechargeable batteries today. They also represent the oldest design with one of the lowest energy-to-weight ratios. Also, the energy-to-volume ratio is low compared to other types of batteries. The power-to-weight ratio can be quite high, however. They are relatively low-cost and can supply high surge currents needed in starter motors. Every reasonably modern car uses a lead-acid battery for this purpose. They are also used in vehicles such as forklifts, in which the low energy-to-weight ratio may in fact be considered a benefit since the battery can be used as a counterweight.
     Lead-acid car and motorcycle batteries for a '12 volt' system consist of six cells of 2.1v nominal voltage. Each cell contains (in the charged state) electrodes of lead metal and lead oxide in an electrolyte of about 37 % sulfuric acid. Modern designs have gelified electrolytes. In the discharged state both electrodes turn into lead sulfate and the electrolyte turns into water. (This is why discharged lead-acid batteries can freeze.)

Lead acid batteries for automotive use are not designed for deep discharge and should always be kept at maximum charge, using constant voltage at 13.8v (for six element car batteries). Their capacity will severely suffer from deep cycling, due to sulfation, or hardening of the lead sulfate. Specially designed deep-cycle cells are much less susceptible to this problem, and are required for applications where the batteries are regularly discharged such as motorcycles. Also, marine batteries are something of a compromise between the two, able to be discharged to a greater degree than automotive batteries, but less so than deep cycle batteries.

     Harley-Davidson AGM (Absorption Glass Mat) Battery
     Sealed battery technology was originally developed in 1985 for military aircraft where power, weight, safety, and reliability were paramount considerations. 
     AGM battery technology has continued to develop and offer improvements over other sealed battery technologies. AGM technology has become the next step in the evolution of both starting and deep cycle sealed batteries for motorcycle, marine, RV, and aviation applications. This "next generation" technology delivers increased safety, performance, and service life over all other existing sealed battery types, including gel technology. 
     In AGM sealed batteries, the acid is absorbed between the plates and immobilized by a very fine fiberglass mat. No silica gel is necessary. This glass mat absorbs and immobilizes the acid while still keeping the acid available to the plates. This allows a fast reaction between acid and plate material. 
     The AGM battery has an extremely low internal electrical resistance. This, combined with faster acid migration, allows the AGM batteries to deliver and absorb higher rates of amperage than other sealed batteries during discharging and charging. In addition, AGM technology batteries can be charged at normal lead-acid regulated charging voltages, therefore, it is not necessary to recalibrate charging systems or purchase special chargers.

    A battery will most often fail in three different ways, won't take a charge, won't hold a charge, and won't release the charge under load (lights and electrical work but it won't crank the motor over).
Have the battery tested if you suspect it to be bad (insist on a "load test").

     Click here to learn more about the differences in battery construction

 

     Charging System Operation
     Using the rotation of the engine, the magnetic stator rotor rotates around the stator windings turning magnetism into AC voltage. Electrons flow to the regulator/rectifier which converts the AC voltage to DC voltage and regulates it to approximately 14.5vdc, routing the excess voltage to ground. The 14.5vdc is routed to the battery (usually by way of the main breaker), recharging the battery.

     Charging System Tips
     Never "Jump" a motorcycle that has a low or dead battery. Motorcycle batteries should be charged at a 2 amp per hour or 'Trickle Charge" rate.

 Never jump a bike battery from an automobile or anything with a higher amperage than your bike. Never charge the battery in the bike at any greater rate than 2 amp/hrs (you could fry the regulator).

Remember that this is not an automotive system and it does not work the same as automotive systems, if you disconnect the battery the engine will not stay running.

Here is the fun part: often when your regulator goes bad, the stator cannot release it's power and will toast itself. The Catch 22 is that often if you install a good regulator to a stator that has gone bad, the malfunctioning stator will fry the new regulator and if you install a new stator with a bad regulator, again it's possible to toast the new stator. (Confused yet? Wait, it gets better) The only way to test to see if the regulator is bad is to test the battery and stator and then test the system with a "known- good" regulator and see if that cures the problem.

If the stator AND regulator are in question - REPLACE THEM AS A SET!

(More on earlier charging systems coming soon)