Electrical puzzle

[Kevininwa]

I've got an issue with our new 28'Argosy that I'm trying to figure out without digging into all the electrical stuff (That will come later, but I have more pressing concerns). It has three batteries- a chassis battery and two deep cycle house batteries. The engine and first battery are next to the driver in the correct spot but the second house battery is under and behind the univolt in the storage. I thought it was a funny way to set it up, but I determined that it was separately wired to part of the DC panel. So some of the system is one battery and the rest is the other. Now I just found out it is not connected to the univolt. Some of the lights started to dim after a couple of hours so I plugged into shore power- half the lights stayed dim. Then I pulled the plug and started the engine. The dimmed lights immediately became brighter. So that means (to me) that part of the DC system is charged by the alternator, and it appears there is no isolator. Is that just wrong, or is there a wisdom I'm not seeing? Other than that, the PO kept it up very well.

[wxbuoy]

I am no expert, but I think it is wrong. Most likely a previous owner wanted to add a second battery (3rd total) and direct wired it. If there is no isolator, I don't know why it isn't dragging the start battery down as well when it gets dim.

I think there has to be a small isolator or something to prevent discharging the start batt. It may be hidden as well. Can you trace the wire back to where it gets its power? That would help allot in figuring out the mystery.

Good luck, keep us posted!

[Kevininwa]

Thanks for the input- my worry would be how that third battery is connected. The lights became brighter right after starting, so I was trying to understand how an isolator would work in that situation. If the engine battery was fully charged, the isolator send the charge to the other battery, right? If so, the worst case would be that I replace the battery (does not hold charge long) and put the task of addressing it further down on the list. I see from the dc panel that the engine battery is not connected at all, but I think that just means the univolt won't ever charge it.

[idroba]

It is always hard to tell, even when you are standing at the vehicle, what a PO has done, especially electrical things.

I had a '78 24' Argosy Motorhome so have some understanding of what you have.

The original setup was one engine battery, one coach battery on the side up near the drivers seat. The coach battery was a type 24 and one was marginal for powering the coach when sitting. I cannot recall now if that motorhome had an electronic isolator or a mechanical solenoid isolator between the two batteries, but it did charge both while driving. The converter/charger only charged the coach battery.

What your PO has done is to add a second coach battery for more capacity. I did the same thing on the Argosy I had. The real issue is how it was wired in, both on the charging side and the user side. And that, from affair, is really difficult to say. From the lights getting brighter note, it does sound like somehow it is tied into the engine charging system. I am not clear if the part of your coach which is still on the original battery also has it's lights brighten when the engine is started. But apparently the new coach battery is not being charged by the converter/charger you have. Is that all correct?

So, at this point I am not sure what else to say other than to ask those questions. Wish I was a bit closer to you, I would help in person. As I said, until one is staring at the thing up close it can be very difficult to diagnose what a PO has done and how to fix it properly.

[mayco]

You may want to try and put it back to original condition and start fresh. There are probably enough people here on the forum to help you with pictures and narrative to get it back to how it was supplied by the factory and then make a fresh start. Then you can determine what your needs are and what mods you may want to make. That sounds a bit daunting i suppose but it very well may be with the effort. At least you would know for sure whats what. Just an idea. Good luck. Youll get it figured out. Ive learned one thing for sure with my classic and that is to never make assumptions, especially with the electrical systems. It seems that most of the time when i have assumed it would be done this way or that.....i assumed wrong!! Airstream had their own way of doing things and it seems to me that you can have the same year and model as someone else yet there will be differences in the way each coach was wired. Sometimes small, sometimes not so small. But, im sure that you can get it back to at least close to original and then dig in with mods. Youll figure it out.......one way or the other im sure.

[Kevininwa]

I have an update to the story. The main fuse from the battery to the fuse panel looked good, but was not. I put a good fuse in and it may solved part of the puzzle. Now both aux batteries appear to be charging. I think that the increased voltage in starting the engine was hopefully due to the engine battery being full and the isolator kicked in for the other battery. I still need to figure out why the 12v system is separated. We want to go out next weekend, and I'm trying to determine how shipshape she is. I received a glowing report from the mechanic concerning the engine, suspension, and brakes, and new tires come in Wednesday.