When my vehicle is parked for a few days it will not start. I charged the battery with a batery charger. The van started. Next day it would not start. So i bought a new batery.It starts now no problem. How do i know if my alternator is charging properly? Gil

You may not have needed to buy a new battery, depending on the age of the battery and the year of the vehicle. I have owned these mini-vans for over ten years now and one problem they seem to have is build up under the positive battery post. This is usually an oxide of some kind building up on the battery post from the battery acid and then isolating the battery cable end from making contact with the post. All I've ever had to do is clean the battery post and cable end and tighten it back up and it works fine. Battery post treated washers (red and green) help this as well as putting battery terminal grease on the cable end once installed to keep corrosion from building up again.

If you have a side post battery situation you'll need to take the battery cable off the battery and clean up the bolt with a wire brush and inside the battery connection with a small wire brush kind of like a bottle brush since the threads are not very big. After cleaning apply a "thin" coat of dielectric grease. This grease is conductive and will give a better contact and keep corrosion away.