Breakers are generally chosen for the wire size that they are protecting. Going to a larger breaker defeats the purpose and creates a fire risk.
That said, it’s not impossible that a smaller breaker than what the wire can handle was used. You’ll have to look at the wiring and determine an appropriate breaker or upgrade the wiring to handle a larger breaker.
Is the breaker a factory part? Seemsodd that the output of your converter is protected at a lower current than the converter can provide. When the batteries get low enough, the converter is going to try to send enough current to charge them and you’ll see just what you are seeing.