Welcome to JOF
In most RV's there are items (LP alarm, radio, TV amplifier, etc.) that can draw down the battery(s) if the RV isn't plugged into shore power during storage allowing the converter/charger to do it's job.
Bob
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2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)