I would think they would charge a battery fine, but keep in mind the amperage of the converters. I'd put a circuit breaker in between, lets say a 40a breaker for a 45a converter. The battery won't charge all that quickly, depending on the converter. Although at 40a, it would be a decently quick charge. Even 5a will charge a battery over time...look at a regular battery charger. If you wanted the same converter to double as a charger as well as still provide power for other things- radio, etc. then you would probably want to limit the charging circuit to maybe 20 amps, leaving 25 to run other things.
Just shooting from the hip here...someone will have to chime in if I'm off the mark on something.
Jim