There are a lot of good theories and/or troubleshooting in this thread. Having been down a series of alternator/charging system issues lately, and still ongoing, I want to throw in a potential monkey wrench, however.
In another thread (
http://www.thorforums.com/forums/f8/...tml#post199620) I had issues with what was determined to be a bad alternator. It was first replaced with a rebuilt alternator and I thought all was well as it was charging nicely at 14+ volts. I then found that the alternator was also putting out 30 volts AC and when the engine was off the alternator was actually drawing several amps of current from the chassis battery. This indicated a bad diode so the alternator was then replaced with a genuine Ford $500 one.
This brings me to the current issue and my reason for posting in this thread. The new alternator puts out 13.3 volts, and never changes with load changes or engine RPM. It is "charging" as when the engine is not running the battery is stable for many days at 12.7 volts. So you definitely see the increase in voltage from the alternator, but it is a lower voltage than typical.
The battery dash light comes on after a couple minutes when the engine is running and stays on. I think these symptoms are very similar to that of the OP, if I'm not mistaken.
My 2014 Windsport has the Battery Control Center (BCC). In my troubleshooting, I completely removed the House Battery system from the BCC, so that only the Chassis Battery is in the circuit - no connection at all to the house. The symptoms are exactly the same! So in my situation, the problem cannot possibly be the Converter (newer unit, working great) or the BCC system. The batteries have been load checked and are almost new and in good condition. It's a problem with the F53 side of things, and most likely just a bad alternator off the shelf. Hopefully I will find that's the answer but I'll let you know when I find it.
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