Did turning the breaker off and on again reset the converter?
Does this mean the converter is bad and needs replaced?
Converter is working as the battery is charging.
If you have had the same battery since 2011, it is likely easily drained with the power being turned off and went to "empty" on your gauge.
I don't believe you need to do anything on a seasonal site with power all the time... however you may want to remove the battery and take it to a national auto parts store. Most are equipped to check the battery and tell you if you need a new one.