Speculation
For a decade, we have been topping up our house bank about 2 or 3 times a year. It takes a little distilled water, but not very much.
I wonder if that charger has a thermal breaker in it, and some other internal component or part on the pc board gets overheated or distressed in some way and trips it. Startup Process then starts over.
This is only a guess... but I notice that if I power down the charger and then back up again it charges at a high rate for a short time while it senses what load that battery bank can accept.
Oh wait... another random thought.... These chargers have a mode where they apply high amps to desulphate a battery, if I remember right. That might be a pc board or chip that is timing on and off when it should not.
How about a call to the parent company, Xantrex?
Several years ago I had occasion to call and one of their engineers was quite helpful on the phone.
Wild guesses and speculation provided while U wait! Operators are (not) standing by!
Loren