The detectors going off is signally low voltage.
Replace the battery and then also check the output of the converter at the converter. If it is putting out too much it will boil your battery, too little will give you the signs you are seeing now.
Leave the tester on the convertor after it reaches what is called for in the specs. I had one that it would reach spec but the only way we found out it was defective was by leaving the tester on and we found it was skyrocketing and frying each batter I put it in the coach.
Replaced it and opened the bad one up and one of the capacitors was totally shot. Literally looked like someone shot it with a 22! :B
