I
One other question also. In the generator compartment above the solenoid
there is a device about 1.5 inches in diameter with two terminals on it.
It appears to me to be a fuse as it appears to be a short between the
terminals.

I was following the recent discussion about the batteries with a particular interest. I have now completely replaced the line from the engine batteries to the house batteries. The line was definitely the original line installed and the line had not faired very well in the past 45 years as the line was very corroded and all the insulation was chipping off. So I am glad that I have the line replaced now.

I also want to thank those that discussed the dangers of charging two 12v batteries in parallel. When I picked up my RV last year it had two dissimilar batteries for the house batteries. I had planned in all the rewiring that I am doing to put both in parallel. On first thought it seemed like a great plan, but I am glad to read the discussion about the internal resistance of the batteries. Never would have thought about it from that angle and quite possibly saved me a disaster.

The solenoids at each end of the line appear to be original also. I was thinking about replacing them also, but then thought about my plans to replace the battery isolator. I have been looking at replacing it with a Victron Cyrix-ct or a Li-Bim isolation module (if anyone has any strong opinions of either, I would love to hear them). In replacing the battery isolator with current technology is there still any need for the solenoids? I can not think of a reason but I figured I would ask here of those of you that are much more knowledgeable about the GMC electrical system.

One other question also. In the generator compartment above the solenoid there is a device about 1.5 inches in diameter with two terminals on it. It appears to me to be a fuse as it appears to be a short between the terminals. Although I as am writing this I started to wonder if it is actually a diode to allow current to flow back to the engine compartment for boosting the current to the starter motor. Can some one identify this device or confirm my latest suspicion?

--
Gerard Hickey / WTØF IRLP:3067/Echolink:529661
hickey@kinetic-compute.com DMR: 3102272

As I read it the Li-BIM is a combiner tuned slightly differently. What I have a problem with is your removal of the front solenoid. The front and rear solenoids have nothing to do with charging batteries (front or rear). Both solenoids remain open for 99+ % of their life and are only energized and used when the boost switch on the dash is pressed. Someday you are going to want that emergency boost function to work to move a couple hundred amps to start the coach.

I might be reading this wrong and I'll go look again. I think you are mistaking a combining function for charging rather than boost function of several hundred amps used for starting.

I will go look again. What is the maximum capacity of this item when combining?