RT,
You may be misinterpreting what you are seeing.
You say that the battery did not discharge in 4 days.
If by discharge, you mean that the lights got dim and things didn't work?
Then that is part of your problem right there. When to lights go dim, that is typically about 10 volts. That is an 80~90% discharge. You can't do that to lead/acid batteries. They are damaged by any more than a 50% discharge.
That the lights are dim after connecting to shore power indicates that the onboard converter/charger is not doing what it should. This can be either the converter of the battery is that badly damaged.
With the information available, all I can suggest is that you check out the installed system and determine that it is/is not working as it should.
You should also be aware that if the new trailer was shipped with, or fitted with a battery while on the lot, it may have been discharged there to the point that it was damaged.
Matt
Matt & Mary Colie
A sailor, his bride and their black dogs (one dear dog is waiting for us at the bridge) going to see some dry places that have Geocaches in a coach made the year we married.