i take it that voltage was checked before and after vehicle parked over night?could be alternator-try overnight with alt disconnected, has battery been tested could be faulty cell, is battery correct cca and amp/hour rating for your model of van,has engine to chassis earth lead been checked/cleaned/tightened,is rear interior light switched off when all doors closed,is it fitted with glovebox light does it go out when closed and is engine oil correct grade for your engine.may be starter faulty if all above ok?
k
May 2011