OK, I'm going to TRY not to hijack this thread, but this is something I've been wrestling with for a couple of weeks and JUST got back from a week's vacation on the boat and had a tough couple of days on the hook without house power.
I've been having battery capacity issues. I recently upgraded to two Group 31 AGM batteries. I've been having significant issues maintaining house power. recently I left the boat on anchor with a fully charged house battery and the anchor light on. I came back about 6-8 hrs later and the battery was dead. I've been running a Honda 2000 to charge the battery and after 4+ hours with nothing but the charger running, my 12v systems continue to slowly die. I would think that at the very least the generator would be able to maintain the existing charge without drawing on the battery. At the time I had the fridge off.
Steps taken so far:
1) I've been leaving my fridge turned up to 5 while on the battery. I've since been turning it completely off.
2) I 'discovered' the wife was using a 12V cigarette lighter style mount for her iPOD. In the car, it doesn't get power when the ignitiion is off. On the boat it does. We've since unplugged it.
3) Stopped playing CD's and now only play FM stereo when on battery and limit its usage.
I'm still getting very poor battery life on brand new AGM batteries. The only change I recenlty had was the pressure water pump was not getting any power. I found it, like many other 12v devices on my boat was connected directly to the battery. I had decided to run it up to the fuse bus at the dash to ensure it was on teh battery switch. I noticed this was causing the lights to dim and the stereo to cut out when the water was turned on.
I've since completelly disconnect the pressure water pump. After doing so, I could get the charger to flip to float while running the generator. I was able to wake up on sunday morning and actually run the stereo the next morning and I had lights the next morning as well.
-> Could the length of the run to the fuse bus at the dash cause such an issue?
-> I notice that my guages all drop when I use 12v at the dash, such as Outdrive Trim or tabs. Could a short cause such a draw on the battery?
-> I'm considering moving both Group 31 AGM, into parallel for the house and adding a smaller starting battery for hthe motor.
I'm just trying to chase this issue down. I've removed as many variables as I can, but I'm not sure where to go next.