How does a Permanent Magnet Alternator (PMA) work?

A Permanent Magnet Alternator is a modified car alternator in which the electro-magnet in the rotor of the alternator has been replaced with a very strong Neodymium rare earth magnet. Why do this? Well if you're trying to make power from wind, hydro (water), or other alternative power source, you need to squeeze every bit of energy you can out of your generator and not let it go to waste. A standard car alternator has the help of a big gasoline powered engine to help it produce power so when the engineers designed it they werenít concerned with creating a truly efficient design. The standard rotor that spins inside an alternator contains an electro-magnet, which when energized creates a magnetic field inside the alternator creating energy. It takes at least 3 Amps  or about 40 watts to energize this magnet, and that is power that is wasted. Those 3 Amps can be very precious on a day when there isnít much wind and you are wasting the first 3 Amps of charging power just to power that inefficient electro-magnet. But the rotor is not the only difference. The stator coil is also specially designed to generate more voltage at a lower RPM than a standard car alternator. This allows us to tailor the output of the alternator to best suit the application it will be used for such as a low RPM direct drive wind generator or a high RPM hydro setup.
   As a result of the Permanent Magnet design, there is no longer a way to regulate the output power from inside the alternator, so this must be accomplished by external means. A Diversion or Dump load controller is the best choice as it diverts excess energy into a heating element or other load when the batteries are fully charged.
  See the articles on charge controllers on the FAQ page for more info on this subject.
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