Newman, here is what I did. Yesterday unplugged ac from TT. Today both batts were good. Disconnected both batteries and reconnected ac. Tested from converter 13.67v steady. Tested unconnected battery 1 tested 12.74v and battery 2 10.65v. While batteries were disconnected no fluctuation in lights or outlets but got speaker buzz with stereo off. Reconnected batteries & ac and turned on lights and nothing went wrong. Started heater and all problems returned, fluctuations in lights and ac outlets. Turned everything off and converter was clicking. Found converter, it is a WFCO WF-8845.