Yes, plug into a regular outlet and let the converter charge the battery with the breaker on. Do the outlets work? Then flip the converter breaker and see if the outlets go off.
BTW "conv" may not even be the converter. Many use that "conv" as short for convenience outlets.
"batchg" seems more like "battery charger" and might be the converter. But again it may control some of the outlets also on that branch.
Often there is a minimum of two branches including the GFCI branch circuit and a second branch of non-GFCI.
Also need to discover what circuit your fridge is on or just know to set the fridge to propane only.