After coffee and muffins this morning, I went next door to check in on our next door neighbor Randy and his batteries.

Yesterday he came over with a problem with his chassis and engine batteries. Although he had been here for several days, and was plugged into shore power, his 12v batteries, both chassis and engine, were going dead.

After spending a little while looking at the setup in his 2001 Monaco Diplomat, the only thing I could see was that his Magnatek Converter was turned off at the control panel. And turning it on seemed to start the batteries coming back up. He said he hadn’t turned it off, so I thought he may have bumped with his shoulder since it’s in the hallway.

But when I went back over to check this afternoon, he was still having problems. He said later in the evening the converter switched off and the batteries dropped back down. He had been on the phone with an RV Electrical Tech who was having him check all of the big heavy-duty fuses in the electrical bay by putting a voltmeter across them. The tech thought maybe the batteries weren’t being charged because the 250 amp fuse between the converter and the batteries had blown.

If a fuse has power on it and you put a voltmeter across it, the meter should read 0.0 volts. If the fuse is bad, you should read ~12volts. But all of the fuses, especially the big 250amp one, read good. But once Randy moved out of the way, I got a closer look at the fuse and saw the problem.

The 2/0 cable came from the output of the Magnatek converter to one side of the fuse block, just as it should. But the other end of the fuse went nowhere. There was a stud with a nut and lockwasher on it, but nothing was connected to it. And the nut was loose.

So the power converter was not connected to the coach at all. And apparently hadn’t been since he bought the rig a short time ago. I think only thing that kept him going was the 3 big solar panels on his roof. But the last 3 or 4 days have been overcast and rainy without any sun, so it finally caught up with him.

He has a setup I haven’t seen before. His house batteries are six 12volt batteries, arrange in two banks of three batteries, with these two banks in parallel. But each set of the three batteries are housed in a black plastic box with a set of terminals at one end and two water fill caps for each battery. The internal connections paralleling the three batteries are all internal to the plastic box. No problem, just different.

I then started tracing out cables, trying to figure out where the missing cable was that was supposed to go from the fuse block to the battery, but it wasn’t there. There was no loose or unused cable. But as I was looking, something kept nagging at me about the way everything was wired up. Then it hit me.

The first thing I saw that that both the engine batteries and the house were wired directly together with a big 2/0 cable. Right off the bat, this explained why both sets of batteries were being pulled down. Normally there is a isolator between the two sets to prevent this from happening, so that if you run you house batteries down, you can still start your engine or generator to recharge them. But not wired up this way.

On the back of the compartment I saw the isolator mounted on the wall. In this case it looks to be pretty much a standard automotive starter solenoid. And it was wired up, but for some reason it was wired between the two banks of HOUSE batteries, not between the house batteries and the engine batteries.


In looking at the cable length, it looked like the short cable now going from the isolator to the house battery bank should go instead over to the unconnected end of the fuse block. This would get the converter output in to the battery banks.Then it looked like the long 2/0 cable going from the engine batteries to the house batteries should instead go to the isolator.

To try and set this right, I disconnected the short cable from the isolator and touched it to the stud on the fuse block, getting the expected spark. And as I held it in place, I could hear the converter whining as it ramped up to try and charge these almost dead batteries. So far, so good.

But then I encountered another problem. The hole in the lug on the end of the cable was slightly too small to fit over the fuse block stud. So where ever it had been, it had not been here originally. But I was able to wedge the lug onto the stud enough to hold it in place, and it was charging the batteries which was the most important thing right now.

And that’s where we left things for now, as I had to get ready for Jan and I to head down to Alvin for the Alvin Opry Christmas Show.

As far as what happened here, I don’t know. Some of the solar installation stuff looks kind of ‘kludgey’, so maybe it got screwed up during that installation.

Or maybe someone who didn’t know what he was doing, tried to change out batteries or something, and got lost and hooked things back up wrong.

Or maybe more likely, the battery isolator circuit or controller had died, and they were trying to make things so that the engine batteries would be charged as well as the house batteries. But they ended up screwing things up so nothing was being charged on shore power, only from solar, the genset, or the engine.

What I want to know is how a dealer let this get off his lot this way.

Oh, and I want to know who the dealer is so I can stay as far away from him as possible.


Thought for the Day:

Success is a lousy teacher. It seduces smart people into thinking they can’t lose. – Bill Gates