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.

BATTERY ANOMALY: Part Three: Additional Testing

After another day of charging I did some more tests of the suspect battery using the Centech Meter. This time the battery resistance reading had dropped to 9 milliohms. A big improvement from the 194 reading but,  still three times what I had measured back in 2012. In addition the meter said I only had 335 Cold Cranking Amps available from the battery. Manufacturing spec says it should be 1100. So even though after several charging attempts the battery is really not up to snuff and will need to be replaced.

I then decided to some quick tests of the other batteries in the string using the CenTech meter. Starting with the first (most positive battery in the string:

As the above photo shows this battery had 1404 Cold Cranking Amps available. So at least with this test seems good. Next I checked Battery Two:

   

As the readings above show the results are not as good as the first battery. In fact it only shows 884 Cold Cranking Amps available. Not as bad as the suspect battery but, under the spec of 1100 CCA.
Battery three was tested next:

This tested better than battery two but, not as good as battery one. At 1150 Cold Cranking Amps it was just over the battery specifications but, not by much.

After doing these tests and thinking about the age of the batteries I came to the conclusion that it would be better to change out all of the batteries in the 48 volt string. In addition after doing these test in the confines of the under the cockpit space I decided I would position the batteries differently to make access for future testing easier. The next question is do I go for Lithium Ion batteries or stick with the AGM's?

TO BE CONTINUED

BATTERY ANOMALY: Part Three: Additional Testing

After another day of charging I did some more tests of the suspect battery using the Centech Meter. This time the battery resistance reading had dropped to 9 milliohms. A big improvement from the 194 reading but,  still three times what I had measured back in 2012. In addition the meter said I only had 335 Cold Cranking Amps available from the battery. Manufacturing spec says it should be 1100. So even though after several charging attempts the battery is really not up to snuff and will need to be replaced.

I then decided to some quick tests of the other batteries in the string using the CenTech meter. Starting with the first (most positive battery in the string:

As the above photo shows this battery had 1404 Cold Cranking Amps available. So at least with this test seems good. Next I checked Battery Two:

   

As the readings above show the results are not as good as the first battery. In fact it only shows 884 Cold Cranking Amps available. Not as bad as the suspect battery but, under the spec of 1100 CCA.
Battery three was tested next:

This tested better than battery two but, not as good as battery one. At 1150 Cold Cranking Amps it was just over the battery specifications but, not by much.

After doing these tests and thinking about the age of the batteries I came to the conclusion that it would be better to change out all of the batteries in the 48 volt string. In addition after doing these test in the confines of the under the cockpit space I decided I would position the batteries differently to make access for future testing easier. The next question is do I go for Lithium Ion batteries or stick with the AGM's?

TO BE CONTINUED