Sounds to me like you said you had problem with an existing battery? If so:
Don't know about that particular vehicle, but same thing happened to me couple years ago. I checked everything, called a few shops, they told me to get a new battery among other things. I had a friend look at it, and he gave it back an hour later and laughed at me. It turns out the battery terminals were a little corroded or something, not even enough to see, so he cleaned them up and it was fine. This was after I spent to weeks trying to figure if I had a short or a bad alternator. I still feel stupid when I think about it.
Obviously if you have a new battery with that problem, just ignore the above, but it could be a minor connection problem.
Hope that helps.