I could be wrong, but I think that can be a symptom of a bad converter.
I'd suggest doing some research and troubleshooting to make sure the converter is operating properly..... maybe getting stuck in bulk charge mode
Another thought for brainstorming... is on the track of a bad battery.
The old batteries in my golf cart would boil. Turns out I had several bad cells scattered through all the batteries, that were keeping the bank from charging fully so the charger just kept on doing what it does....
Do you have a hydrometer to check the batteries?
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