I have a technical question about the alternator and the battery charge. When you strart up your vehicle on a low battery, eventually the battery will reach full charge. The charge generated by the alternator recharges the battery. When you have a full battery, however, what happens to the charge that the alternator produces. Is it simply pumped into the fully charged battery or where does it go? Seems like a tremendous inefficiency because performance doesn't seem to be influenced much by battery charge. In all situations, the alternator cranks out charge (irrespective of battery charge and applicance energy draw). Would appreciate it if someone with more experience or more automotive knowledge would check my conclusions. I have very limited knowledge in this area and would appreciate any assistance you guys can provide.

Thanks!

The alternator as used in motor vehicles does not use a permanent magnet. It uses a field coil/electro magnet. This takes its supply from the battery via a regulator. In this way the regulator can control the output of the alternator by controlling the field strength available to the stator/generating coils. Some times there are two field coils which can be switched on/off individually or together. This is just another method to control the strength of the field at the stator. Hope this is an understandable explanation for you.