MORE BATTERY ISSUES: The 12 volt House bank

After installing and testing of the new 8A4D battery for the electric propulsion bank I noticed the 12 volt house bank was experiencing some issues too. What tipped me off was the Morningstar Solar controller was cutting off voltage to it's output lugs. I had wired my Engel refrigerators, AIS, and Fan to this output. The controller cuts the output when the battery voltage drops below 11.4 volts. It looks like one or both of the 8G27 Gel Cell batteries BIANKA uses for the house 12 volts had reached the end of their useful life.   As I opened the compartment that held the batteries I could feel some heat rising from the space.

I took out my infrared temperature probe and took some measurements. One of the batteries measured 141 degrees fahrenheit.

 Way too warm for comfort. The temperature of the second battery had a much better reading of 107 degrees fahrenheit. Much cooler but, still warmer than normal.

Since both of these house batteries are operated in parallel it said to me that the hotter battery was the major problem. As the cooler battery was trying to continually charge the defective warmer battery. I turned the battery switch from "BOTH" to the individual settings and took some voltage readings. The warm battery was around 10.5 volts and the other was over 12 volts. So one battery was truly defective but, I replaced both since ten years providing the house 12 volts was a good run and best practice is to have both batteries the same age when installing them.

After I installed the new 8G27 batteries I used the Centech Battery analyzer  to get a baseline reading of each.

They appear to be pretty closely matched though their cold cranking amps was slightly lower than the  spec but, I am not too concerned. I will recheck them after they have been in operation for a bit. All in all I can not complain about these MK 8G27 Gel batteries.  They were installed when I converted BIANKA to Electric Propulsion in 2008. So ten years was a god run. I hope the new ones last as long.