I can guarantee that from BF's onwards they use the smart charge system. like I said I'm not sure if its the same or even similar to the focus ones, but they do run a smart chatge system. The Altenators aren't different, neither is the battery or any other associated components, its just that the voltage charge is controlled by the PCM rather than a voltage regulator (I think) so just because the focus altenators keep sh*tting themselves, doesn't mean the smart charge system is crap, and just because its hard to diagnose, doesn't mean its crap either Anywho like I said I'm not sure how it works, but it may cause different readings.