Alternator for Duratec

[Ross_328i_sport]

My alternator is starting to inconsistently re-charge the battery on my 2.0L duratec.

The car is primarily used for track days therefore rather than replace like for like if there are smaller lighter units available where would be the best place to source?

One further question in relation to the reliability of the smaller units are they as reliable or being lighter do they not last as long?

Thanks in advance