May 3, 2010.
Lets talk batteries for a minute. We have 4 large 4D batteries in our battery bank. 3 batteries were dedicated to the house bank while the fourth battery was the starting battery.
We never used the starting battery so a couple of years ago with a flick of the master switch I added it to the house bank. A few weeks ago a problem began to surface. I checked all the batteries and found that one of the 4 batteries had given up the ghost. It was completely dead, charge it all you want, remove the charging source and nothing, dead.
Fortunately, it was the starting battery so it was a simple matter of flipping the master switch back from “ALL” to “HOUSE”. That removed and isolated the dead battery from the equation.
The rest of the batteries haven’t been holding a charge all that well either. We used to wake up with the batteries around 12.7 volts but lately they’ve been around 12.2 volts. I figured that the batteries were finally all showing their age and would need replacement soon. That was until we motored those last 8 hours during our crossing……
We haven’t run the engine continuously for 8 hours since we headed south from Annapolis last fall. While we were motoring the other morning we smelled something burning. Something electrical. After checking everything I could think of I realized that the smell was coming from the starting battery which should have been isolated from the charging system.
I got out my heat gun and found that the battery was at about 192 degrees. The other 3 batteries were at about 92 degrees. WTF?. So the smell was the boiling battery and then I realized that the starting battery wasn’t isolated from the rest of the batteries or the charging system.
I had forgotten about the series of battery combiners we have installed in the system. The master switch only disconnects the batteries from the possible loads on them. The battery combiner is like a secret backdoor which only comes into play when theres a charging source detected. So whenever the solar panels were sending amps to the batteries the combiner saw the dead battery as being the most needy and sent amps that way even though the battery was toast. This robbed the good batteries of the amps needed to bring the voltage up high enough to last well through the night. It all became apparent because of the alternator putting out a lot of amps for an extended time. It literally fried the dead battery which caused me to realize that it was still “in” the system.
The individual combiner for each battery comes equipped with an integral breaker. I popped the breaker for the dead batteries combiner to finally truly remove it from the system and now all of a sudden the rest of our batteries aren’t looking so shabby. Christy was happy because there is no more burning smell.
We rarely run the engine for extended periods of time but this time it worked out in our favor. It taught me that I’m still a bit of a dumbass myself.