[Flick]

Scott you sound like us except I don't have a handy neighbor. But thank God for the gurus because they have helped a bunch. The electrical system is still a mystery to me including the merge switch. First of all my 84 has three settings on the merge switch. In the middle I assume is off. Up is on as well as down. I have 2 8D batteries in the house and I hVe two more 8D's one each in small bays in front of the rear wheels on both the drive and passenger side.

I am also not sure what up and down does and if while I have them in a merged position does that mean that all are being charged. In fact I am not even sure if the merge switch is for the house or the chassis batteries. Now here is the cool thing about the gurus. Over the next day no one will mock us they will just lend their wisdom to our questions. Just watch.

Actually they may mock me because I met most if them in South Dakota for our rally this pSt summer. If you are coming here to our fine state let me know. Love to see your coach and we can tell some place to stay, things to do and things to see.

[HoosierDaddy]

OK Todd,
I'll go easy on you since we haven't met!!!!!!
The merge switch mystified me at first. What follows is my idea of how it works: The merge switch may be used if one set of the batts is dead. The merge switch operates the merge solenoid that connects the two battery banks together. Twelve volt current is required for the merge solenoid to function. The Batt merge switch sends 12 V to the Merge solenoid. The two energized positions on the merge switch allows either the engine batts OR the house batts to energize the merge solenoid.
I will humbly step aside if a more Knowledgeable Guru sees a flaw in my understanding!

[Flick]

So do you only use it when one set is dead? So to start the engine or start the generator?

[Fulltiming]

The engine (chassis) batteries don't have to be completely dead to not start the coach. Any time it is cold or the batteries don't have a good charge on them, merging the batteries can add extra power to get you started. With the switch in the center position, the house (or auxiliary) batteries are isolated from the engine (chassis) batteries. The generator is typically wired to start from the house batteries. If your engine batteries are low, place the merge switch in either the up or the down position and see if that allows you to start the engine. If one set of batteries is REALLY low, the merge solenoid, as Dean pointed out, may not engage. If this is the case, flip the merge switch to the opposite merge position and it should tie the two systems together. Under most circumstances, there is enough juice in either set of batteries to engage the merge solenoid so it will not matter whether you flip the switch to the up position or the down position. Newell was just eliminating another potential reason for you getting stranded.

[Flick]

Another question. When I am on shoreline are both sets of batteries being charged? What about when I drive does the alternator charge both house and chassis batteries?

[Fulltiming]

When you are on shore power, ONLY the house batteries are being charged UNLESS you have the merge switch on. When the alternator is providing a charge, it SHOULD activate the merge solenoid so that both battery banks are being charged by the alternator. Newell recommends replacing the merge solenoid every year. I don't do that but I have replaced at about 3 year intervals.

[wepaddle4]

I guessed right on the function, the two positions make sense now

I have the same setup (4 batteries), one house battery was dead, dragging the other down. I presume replacing in pairs is advised. The alternator gave up as well; I pulled it off, it's at the shop to see about a rebuild but they were leaning towards a replacement based on lack of parts for a 1982 Motorola 8S.

Scott

[Ozarkguy]

Just remember, your battery bank is only as good as the weakest battery. Depending on the age you may want to replace all. There is a lot of conversation on this site as to recommendations.

[Flick]

Michael where is the solenoid located and what does it look like?

[Fulltiming]

FYI, on my coach, the up position, the house batteries provide the power to the relay and in the down position, the chassis batteries provide the power to the relay.

It is in likely in the rear electrical panel. Depending on whether it has been changed or not, it will look like a a round silver can about 2-1/2" tall and an inch in diameter. It is located near the starter relay BUT it is NOT a starter relay in that it MUST be rated for continuous duty. A starter solenoid will burn up after a few minutes when used in this application. Don't ask how I know ;-)