Community Forums

castrol · 06-18-2015, 03:17 PM

Quote:

Originally Posted by Papa_Jim

Somewhere in your engine bay you should have an isolator that looks something like this picture.

The middle post is where your alternator output wire connects to. You can check that post for your alternator output. If it's not OK, then your alternator or the wiring at your alternator is the problem. It it is OK, then the alternator is OK, but the isolator may have failed. To test the isolator, then proceed as follows. If the right post is for your chassis batteries, the left post will be for the house batteries. Test the output at the right post. If it's not OK, then the isolator has failed. If it tests OK at the right post, perform the same test on the left post.

Jim

Jim, I'll be checking that this weekend. Another important thing to note, the switch that links the batteries together, (battery boost maybe?) didn't work at all. I tried that when we broke down the first time because that was always my go to in the dolphin. It didn't do ANYTHING in this coach.

castrol · 06-18-2015, 03:18 PM

Quote:

Originally Posted by twinboat

If you have a diode isolator, like the one in the picture, you won't see 12 volts at the big post.

If that's the case, you must have the sense wire hooked up.

The alternator needs to see charging volts from on or the other, to send feedback to the internal regulator.

With no feedback the alt will output full volts and amps, until it burns up or the isolator blows it's diodes.

A test for a bad isolator, is to jump the posts together and check for charging volts at the batterys.

Which posts would we be jumping together? All three?

twinboat · 06-18-2015, 05:10 PM

All three for testing

dennis45 · 06-18-2015, 05:20 PM

Quote:

Originally Posted by DtBt

Something does not look right with the alternator wiring. AKAIK the red wire should be the DUVAC( remote sense) and should be where the purple wire is now. Can someone with a DUVAC alternator verify wire colors?

http://delcoremy.com/getattachment/A...24210.pdf.aspx

I am guessing you are right.
Both alternators are the same but require an addition to accommodate remote sensing. A good Autoelectirc shop will get it resolved for you. One other thing to look for is a fuse for the alternator exciter. With out power to the exciter, it will not charge. I don't know where the fuses are located on your Monaco but on my Spartan Chassis, that fuse is in a Bussman Box labeled ALT. Hope this helps.

pwhittle · 06-18-2015, 08:37 PM

Castrol,

If your isolator is not working and your battery boost is not working, you can replace them both with a Blue Sea ML-ACR 500A magnetic latching relay. I am pleased with mine and got rid of the voltage drop across the isolator. Amazon had the best price at the time.

I had to run a couple wires to the drivers panel, but the provided switch fits in one of the rectangular openings in mine. When you run the wire, run a couple of spares for the next great idea.

Paul

castrol · 06-20-2015, 08:42 AM

I feel like a total noob here. I can't even open the engine cover. I don't want to break anything with my super human strength. There are two hold down latches on either side. I've unhooked those, after moving the mattress of course, and the door still won't open. What am I missing, if anything?!

castrol · 06-20-2015, 10:03 AM

It is very disheartening to have your early morning plans foiled by a single door. How sad!

Hahaha. I've been under, over, around...maybe the lifting arm shocks are frozen?

mel s · 06-20-2015, 10:15 AM

Quote:

Originally Posted by Stretch

Camping World is not my favourite place to have mechanical work done. But since you are already there, I agree with Mike. Take it to your local CW and have them make it right.

Good luck with that!

Stretch · 06-20-2015, 10:59 AM

Just pry it up using a wide bladed screwdriver. First feel around the edges and see if some boob has screwed it down also.

Sent from my iPad using iRV2 - RV Forum

castrol · 06-20-2015, 01:42 PM

Bent the biggest screwdriver I had. Needless to say it probably hadn't been open in years.

Finally used a couple of hammers and made a fulcrum to lift on it. What a bitch.

Opened it up and took the measurements on the isolator. Middle post coming from the alternator=3.0 volts. Other two were measuring normal 12.95 volts from each battery. So the alternator isn't putting out much of anything. I'll measure directly on the output lugs of the alternator next.

castrol · 06-23-2015, 03:32 PM

It's the ISOLATOR!! You guys are freaking geniuses!! I jumpered the posts and the tachometer and voltmeter came to life

Now the question is...what caused the isolator to go bad and will any new one I get burn up too?

twinboat · 06-23-2015, 04:00 PM

By jumping the isolator, you gave feedback to the alternator. If you replace the isolator, that will be blocked again. You need to make sure a battery wire is hooked to the S ( Remote Sense ) post of the alternator.

Another option is to put the Alt wire and start battery wire together, then buy a "Yandina.com" 150 amp combiner or a "Victron Energy, Cyrix" 150 amp combiner and hook it between the batteries.

They are voltage sensing, Bi-directional relays, that will do a good job for you, with no voltage loss.

castrol · 06-23-2015, 04:17 PM

Okay, I'd like to keep it the way it is if at all possible, and still have it work properly... I'm going to trace wires to see where they lead. Did you see the diagram of the back of the Delco that was posted earlier?

There's a post for the battery and a post for the remote sense. Those two should be connected? Is that what I'm reading?

http://delcoremy.com/getattachment/A...24210.pdf.aspx

Loren Rice · 06-23-2015, 04:21 PM

Quote:

Originally Posted by castrol

It's the ISOLATOR!! You guys are freaking geniuses!! I jumpered the posts and the tachometer and voltmeter came to l
Now the question is...what caused the isolator to go bad and will any new one I get burn up too?

Castrol
It could be just a normal death. But could also be that your batteries were on the low side and the alternator has output capabilities greater than your isolator resulting in it's death. So the previous owner could have driven and used the mh with no problems cause he had the batteries more fully charge and didn't pull all the amps that you did.

So when you replace the isolator make sure you know the output rating of your alternator and buy an isolator of whose capacity or greater than the alternator.

My mh doesn't have an isolator -- just a big relay that joins the two battery banks when the engine is running. I don't have remote sensing. But you need remote sensing cause there's a 7/10 volt drop across the isolator coupled with wire losses (which can be surprisingly large) by the time you get to your batteries. some one switched my rig over to a single output alternator (internal sensing) and so it doesn't try to over charge because there is close to a volt drop to the batteries and it just doesn't see all that load. That said I usually have my batteries nearly charged cause of my photovoltaic. Maybe I would have an alternator problem if all my batteries got on the low side.
I killed an alternator in a different mh a few years ago. What I learned is, that your starting battery should be nearly charged before starting off. This is because in a mh with all those house battery banks as well, adds a lot of load that some alternators aren't up to putting out full out put as long as necessary to bring up all those batteries.
So if you put in a remote sensing ckt it probably will be connected to your starting batteries, very close to the batteries because as I mentioned earlier wire, even heavy wire will have a voltage drop across it and to charge batteries the voltage needs to get to 13.8 min and usually is 14.5. That sensing wire will cause the alternator to put out perhaps 15.5 to get 14.5 at the battery terminal. With a isolator the voltage needs to be 16.2 at the alternator to get 14.5 a the battery post. Gets complicated doesn't it?

Hope this helps
Loren