When you say the battery is not charging enough, what do you mean? If you check the battery voltage at the battery with the converter off and again with the converter on you should see a definite increase with the converter on, typically about .5 to 1.0 volt. If you are seeing any increase in this check there is not a blown fuse between the converter and battery.
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.