Your Vee Dub's Charging System

The BATTERY is the heart of the electrical system in das bus. Something has to keep recharging the battery, or it will lose it's voltage and fail to work. This job is left to the charging system. The most important part of the charging system is the ALTERNATOR. It generates and delivers electrical power to the battery and the rest of your Vee Dubb's electrical system. This current must be maintained at between 13 and 15 volts, this is the job of the VOLTAGE REGULATOR. Amperage output of the alternator is dependent on the level of charge of the battery. The charging system consists of the battery, which provides field current to the alternator, so that it can function. The battery also controls the amperage output of the alternator. The voltage regulator, which controls the voltage output of the alternator. An ammeter or idiot light, to inform the driver of the condition of the system.


The alternator produces voltage and current. A magnet, called a rotor, is rotated inside a stationary looped conductor, called a stator, to generate a voltage. The strength and polarity of the voltage is dependent on the direction of rotation, the strength of the magnetic field, the number of conductors and the speed of the rotor inside the stator. This type of generator puts out AC voltage, which is why an alternator is used instead of a generator, while your bus operates on DC current. To convert the AC voltage into DC voltage a circuit of diodes are used. A diode is like a one way check valve that allows current to flow in one direction only. By allowing current to flow in only one direction, we are able to convert AC to DC. Another big difference between an AC alternator and a DC generator is that an alternator will produce a large current flow at low speed, while a generator needs high speed to produce high current flow. As stated earlier, voltage output is dependent on the strength of the magnetic field. The magnetic field is created by applying current to the stator from the voltage regulator.


The voltage regulator controls the field current applied to the alternator. When there is no current applied to the field, there is no voltage produced from the alternator. Sooo, when voltage drops below 13.5 the regulator will apply current to the field and the alternator will start charging. When the voltage exceeds 14.5 the regulator will stop supplying voltage to the field and the alternator will stop charging. This is how voltage output from the alternator is regulated. Amperage or current is regulated by the state of charge of the battery. When the battery is weak, the electromotive force (voltage) is not strong enough to hold back the current from the alternator trying to recharge the battery. As the battery reaches a state of full charge, the electromotive force becomes strong enough to oppose the current flow from the alternator, the amperage output from the alternator will drop to 0, while the voltage will remain at 13.5 to 14.5. When more electrical power is used, the electromotive force will reduce and alternator amperage will increase. It is extremely important that when alternator efficiency is checked, both voltage and amperage outputs are checked. Your alternator has a rated amperage output depending on the electrical requirements for your bus. If you start adding goodies to your bus you begin to approach the upper limits of the "stock" alternator. This will not be an issue unless you add a fairly significant number of additional electrical devices or one real phat amplifier for your CD player!

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