[Chris Burkard]

It is more likely there is a short in the charger, but it could be the breaker. I think that it could also be a short in one of the batteries, but I'm not positive of that. First I would check all of the connections and make sure they are clean and tight. You may want to load test the batteries (must be separated from the bank before you can load test). If all checks out, then check the breaker and then the charger.

Obviously the breaker is cheaper to replace than having the charger repaired. If you are electrically inclined, you could try and swap the breaker for another one of the same Amp rating and see if that solves your problem. If it does not, then the Pro Mariner needs to be sent back to the factory for repair.