Hi pbekkerh,
Thank for the reply,
Well in the country i am staying (Singapore), there are a lot of traffic lights around. Unless moving on highway, almost everywhere about a few hundred meter will have a traffic light. We have to stop if it turn red, if not we will get into trouble. Therefore, idling are very common here.
By the way i have adjust the idling a bit higher about 1.5k rpm. Now the volt meter read about 12.5v, hope it will help a bit.
Thank.