The converters have pretty tricky ratings, so you need to test them on long run.
I have 40 amp converter, but when I start it on discharged battery - it will overheat in couple of minutes and take several minutes to cool down before another charge attempt and overheat.
That takes long time to get the battery charged.
Ford truck has 30 amp trailer charging circuit, but with long wire the voltage drop is significant, so it takes several hr of driving to get camper battery fully charged.
With troubles like above, I would have voltmeter permanently installed and showing what voltage I have at the time.