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thenewkid64 · 12-31-2002, 09:49 AM

My 1976 Motor home came without a Battery Isolator. The engine battery and coach battery are two completely independent systems. I do have a starter booster but that is the only common connection to the two systems.

I want to install a battery isolator, but I am leery of disconnecting the 12 + lead off the alternator. I know on the newer(1980 and up) the battery isolators are accessable from under the hood. Does this mean that there is a wire from the alternator running up to the front of the coach and feeding only the isolator. I just put a new alternator in and I do not want to fry it or the isolator by improperly connecing the isolator further downstream.

So the question is how do I do it??

74Argosy24MH · 12-31-2002, 10:02 AM

The isolator makes 2 independent systems. Feed from the alternator to the common terminal on the isolator, then to the house battery and the starter, starting battery, common lug, whatever the alternator connects to now.

Pull the ground at the start battery first and you won't have any sparking. Watch the wire size of the alternator to the isolator, you will be putting out more current longer when you start charging a pair of batteries.

John

thenewkid64 · 12-31-2002, 12:23 PM

That is what I thought, I just wanted some reassurance that I was understanding the drawings that came with it. I will probly use a #6 wire to go from the Alternator to the Isolator and the same size to get to the coach batteries. Now I just need to find some space in the doghouse/engine compartment.

Thanks for the reminder on pulling the positive cable. I have installed cut off switches on the ground side of both batteries so I can disconnect them while in storage to eliminate parasitic draws.

74Argosy24MH · 12-31-2002, 12:30 PM

Space is where it is at. I mounted mine under the passenger side. All through this on of my first considerations has always been maintenance. This is the one thing that is really hard to get at. If it fails it will probably stay where it is at and I will be looking for a new place to mount one also. My batteries were behind the rf wheel, if yours are the same how about inside the frame rail near there.

John

thenewkid64 · 12-31-2002, 12:44 PM

My batteries are in a weird spot. They are installed directly in front of the heater core and are two deep. The house battery is behind the starting battery, and the starting battery has to be removed to check the house. They are pulled out thru the hood. This was not a well thought out set-up. I am thinking that I may mount the isolator under the pass side seat and just have to run a longer wire to the house battery. I have 2 concerns and they are heat from the exaust and water from the wheels. I may be able to make a cover to keep it from getting soaked, but the only way to keep it from the heat is distance. On second thought I do not want to box it in as it needs to radiate heat as well.

74Argosy24MH · 12-31-2002, 01:04 PM

You might be able to put yours under the kick up for the passenger side where I put mine. You were looking for something to fill that space. My problem is when I put the coolers in there it blocked a lot of access to this. Either that or mount it vertically on the support. You could make a shield to keep it out or the weather and it should still have plenty of free air for cooling. If you keep it close to the batteries you will only have to route 1 long wire.

John

74Argosy24MH · 12-31-2002, 01:37 PM

I moved my house battery where both yours are, have 2 starting batteries in the tray. My house battery is gel cell so no problem pulling to check water, but I do have to lay it on it's side and then roll it upright when it is inside. Where are the mounts for your battery tray?

John

thenewkid64 · 12-31-2002, 03:47 PM

John,

I went out and looked for a place to mount the isolator under the passenger side kick and came up with the same place you show yours. Close to the alternator, but not too far for amperage loss.

On the battery tray it is in the same place as yours but goes straight back. My blower motor for the heat and defrosters sicks out off to the left of the batteries. I am considering the gel route myself as I also have to do the tip and slide to get them in and out and the acid burns! I ruined a brand new pair of shorts when I did it last time from a drip I did not know had gotten me

.

I am also kicking around the idea of using some wasted space under my refer for a slide out battery tray. My refer is between the door and the rear wheels on the passenger side. Under it from the outside is a belly wrap, but no storage bin. I could get a tray in there that would hold 2 or 3 batteries and if I do it on a slide I would not have the difficulty checking them. Hmmmmm

74Argosy24MH · 12-31-2002, 04:08 PM

The space under the refrigerator sounds like a good idea. All my wraps were hinged on the bottom anyway. It took a little time but I got all of them free and working but 1 and replaced that hinge with a stainless one. I had 2 unused spaces behind the rear axle. Ended up boxing the rh in and use it for the jack, etc. It amazes me 2 years and 2 feet difference in length how much change there is in the location of everything. Seems like it would be easy to make a standard location for things like the batteries that were used no matter what length. I drew out my floor frame while it was apart, but I doubt if it is anywhere near yours. If you want a copy anyway to give you a rough idea how they designed a 24 ft in 74 I will send it to you. Might give you a little insight into how they designed it.

John

thenewkid64 · 12-31-2002, 06:11 PM

All of my wraps are hinged as well, and I was lucky that they all open. Of cours all of my bin leak.... the doors do not seal well and with the rain we get here stuff seems to get wet frequently. I have most of my stuff in plastic tubs. It alsokkeps it neater.

The only really "wasted" space in my opinon is the spot under the refer. Ther is a space behind the roadside rear wheels that might be convertable but that is about it. With your short overhang they really packed the weight in on the back. Generator, fuel and propane. My Generator is in the rear curbside corner, Gas tank right behind the driver seat and propane right behind the passenger seat. That gives me storage under driver seat, under passenger seat, in the roadside rear corner and one bin amidships on the roadside as well.

I think due to the low volume each size was somwhat custom, they were still figuring out what would work.

Did you fabricate the new bins from plate steel? Did you get matching locks for your new storage? I would want the tray and door to look original so I would want to use an original style twist lock.

74Argosy24MH · 12-31-2002, 08:04 PM

I used 1/8" plate for the compartment so it is plenty heavy. All my locks were pretty bad. I tried to clean a couple of the best ones up without too much success. Thought about getting them rechromed, but after what I paid for the grill I figured it would be cheaper to buy new. So I got 5 new ones keyed alike with ace locks. That worked because originally they were all different, I had a key ring just for this. I added 4 locks to the outside and only have 3 keys now.

I originally had the 1 propane tank behind the lr wheels, added another on the right. My holding tanks are in front of the left duals, and then a storage tray.
RH is the gas tank and the battery tray. There was enough room between them so I put the trans and engine oil filters there. There is a lot of stuff hanging off these frames when you think about it.

John

thenewkid64 · 01-01-2003, 04:49 PM

So I've gotten the isolator mounted and wired back to the funky wire block on the frame in front of the alternator. I disconnected the 12 VDC output from the alternator and connected the A post of the isolator to it.

But now I have a question.

The wire that connected to the 12VDC output of the alternator spliced to a wire that runs to the voltage regulator. Do connect this to the A post on theinput side of the Isolator or keep it on the output side attached to terminal 1?

I need to get a properly sized wing nut to do the final connection and then it is done. I mounted it under the passenger side floorboard and only had to run 3 feet of wire each direction. The wire to the battery is approx. 5 feet.

I have not started the coach yet because of my question. I do not want to fry my new alternator.

74Argosy24MH · 01-01-2003, 05:15 PM

The isolator has an input and 2 outputs, I'm not sure about the 1 and A. The out put of the alternator/voltage regulator should hook to the input (center terminal on mine, I would guess most of them). Your 2 battery banks should hook to the other terminals.

I checked resistance on mine, I don't think it is anything but a couple of big diodes, open one way, short the other. If you hook it up wrong it shouldn't do anything but charge 1 battery.

John

thenewkid64 · 01-01-2003, 05:36 PM

My concern is the to the voltage regulator. Does it go into the isolator input?

I would assume that it does, but you know how assumptions are.

74Argosy24MH · 01-01-2003, 05:51 PM

12VDC output of the alternator spliced to a wire that runs to the voltage regulator.

Straight into the regulator with another output wire, or is it in parallel with the output of the alternator?

John

26Argosy.ca · 01-01-2003, 06:15 PM

This setup was done before I bought the MH, so I don't know what was done in terms of wiring. I hope to find that out in time...

Anywho, I have a big switch in front of the heater core that switches from battery 1, battery 2, Both or None.

The isolator is on the drivers side, on some sort of homemade bracket.

There is a regular car battery in the center, and the second battery was put behind and below the drivers seat, and is a deep cycle monster which is or has leaked and has corroded some of the metal. In an earlier post I asked about changing it...

This setup seems to work fine for me.

thenewkid64 · 01-01-2003, 06:30 PM

There are 2 wires that go into the regulator there is one that attaches to the 12 volt block on top of the frame near the alternator the other goes into a wire loom. The output from the alternator is also attached to the 12 volt block. So I guess that makes it parallel??? I do not know where the other wire ends up.

74Argosy24MH · 01-02-2003, 03:00 AM

There should be another heavy wire coming off the terminal block that eventually goes to the battery. It probably goes to the lug on the solenoid and charges the battery like that. You need to get this out of the circuit and run a wire straight to the input of the isolator from the block.

John

thenewkid64 · 01-12-2003, 08:27 AM

I have the regulator sense wire connected to the output side of the isolator. HWen I run the engine I have a 17 volt reading at the dash meter for the engine battery, I did not run it long enough to check the coach battery.

I am going to move the regulator sense wire back to the output side of the alternator to see if I get a more normal output.