I've been leaving the refrig/freezer and fans running during the week. This weekend I got to the boat and everything was dead. Noticed that my Heart Freedom 20 Inverter input circuit breaker was tripped and obcourse everything ran on battery until it ran of juice. I reset the breaker, cycled the AC switches and the inverter came back to life and went to 14 volts charging the battery. Let it charge for a couple of hours and then motored for about 30 minutes and went sailing. Turned the refrig off and just had the CD and occassional auto pilot running all afternoon, didn't see any problems. We I got back to the slip I hooked up shore power, inverter starting charging at 14, again seemed normal enough, figured the battery will be charged up by the next morning ( turned refrig back on ). I got on the boat next day and it still read 14 volts, and then I noticed I could actually hear the battery sizzling. I checked the water (it's a 4D wet battery) and several cells were dry and the one that I could see water in was like percolating. I filled the battery up with water, put my meter to it and it registered 12.29 so I went sailing. I had refrig, CD, and due to light winds used the auto pilot more but again things were OK, battery seemed to hold. When I returned to the slip I turned off all DC stuff and let it charge for 24 hours. I got on the boat tonight and the inverter panel and the DC analog panel were reading 13 volts which is what it normally reads but again I could hear the battery sizzling thru the lazzerett. I opened everything up and the battery was very hot to the touch and I noticed it was already low on water in some of the cells. I turned everything off at this point, voltage when to 12.25 and after 20 minutes it was 12.29. I figured I'll wait another day and go take another reading and see what it does with nothing turned on. So, do you think it's the battery not holding a charge making the inverter keep charging it or is the inverter frying the battery?