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Topic: Alternator, Isolator or both? (Read 3073 times) previous topic - next topic

Alternator, Isolator or both?

Fun day! Shortly after leaving the campground the ole girl wouldn't shift out of 4th, so we pulled over and noted that the blinker didn't sound right. Turned the engine off, restarted... nothing. No dash lights either. Tried again and she tried to start. Used the boost and she started right up. We continued and she did it again. This time we noticed that the voltage gage showed 8 volts. Wiggled the wires behind the gage and turned off all the unnecessary stuff and it gradually came back up. Starting required the boost again.
We traveled the remaining 100 miles without any issues. Turning on the lights caused the voltage to drop a bit, so we left them off. 
Note: We were using the retarder both times things went weird.

97 u295 with Cummins 8.3

Update: so we did indeed have a bad battery. We replaced BOTH batteries, but it still looks like we have an issue.

Alternator/Isolator Readings

Coach Running, nothing on
Alternator: 12.38
Batteries: 12.13
Isolator:
-Left: 13.06
-Middle: 12.37
-Right: 12.10
Dash: 11.7

Coach Running, AC, lights and etc on
Alternator: 12.20
Batteries: 11.98
Isolator:
-Left: 13.06
-Middle: 12.18
-Right: 11.92
Dash: 11

How do we know if it's the alternator, the isolator or both?
Note: we will clean the isolator connections as soon as the tornado warning passes....

Re: Alternator, Isolator or both?

Reply #1 –
Jimmy:

Diode isolators are quite reliable. Your low voltage measurements are pointing to the alternator.

The alternator voltage is at least 2.5 volts low and it's unable to handle additional load. How old is it (yrs and/or miles). It can be just a disconnected sense wire, or worn out brushes requiring a rebuild or replacement. Pls post make of alternator, age, photos of wire connections for additional help to troubleshoot.

Re: Alternator, Isolator or both?

Reply #2 –
I would upgrade the alternator to a Delco Remy and upgrade the isolator at this time,and listen to Mr. Fleming,he the Guru.

Re: Alternator, Isolator or both?

Reply #3 –
Hey Peter, thanks for the quick response! We have to assume that all parts are original. They certainly look like it. Everything is very dirty so when I have a chance I'll clean the connections that are reachable. We have another month until we sit still for a while, meanwhile we might be traveling with the generator running.
We will try to get some more pictures tomorrow.

Re: Alternator, Isolator or both?

Reply #4 –
I did take a picture of the Isolator. Will clean the connections tomorrow.

Re: Alternator, Isolator or both?

Reply #5 –
Jimmy,

After looking at that pic. you need to at least clean up the sense wire where it is landed on the breaker.  That breaker sure loos tired so it may have to be replaced.

Mike

Re: Alternator, Isolator or both?

Reply #6 –
Looks like the original,mark every wire and get new resetable fuses and new solenoids,take the mounting plate and paint it and it will look like new.

Re: Alternator, Isolator or both?

Reply #7 –
Jimmy,
I had similar issues with my 2005 U270 while I was traveling and had that same type of isolator. I learned from this forum that you could disconnect the 2 positive wires from the isolator and using a 3/8 bolt, you could bolt the 2 positive wires together and wrap them with electric tape and continue your travels. When I did this, my gauge readings went back to normal ranges, which confirmed the isolator was bad. I drove 600 miles and did not have an issue. You need to understand by doing this you are combining the house batteries with the chassis batteries and if the batteries go dead, you will not have any "boost " capability.

Re: Alternator, Isolator or both?

Reply #8 –
Yes, connecting all the wires on the battery isolator will work IF (yes, big IF) the isolator is the problem.

But, what I would do is clean all connections on the alternator and isolator (you will want to do this anyway, whatever the diagnosis).

Recheck your readings.

If the same, remove the alternator and take to an alternator shop for diagnosis/rebuild.

But, would hate to see you start there only to find out you have a badly corroded connection or wire whose copper has turned to green copper oxide.

Re: Alternator, Isolator or both?

Reply #9 –
Jimmy is outside cleaning connections and I got a few pictures of the alternator. He will clean these too.

Re: Alternator, Isolator or both?

Reply #10 –
Yes, cleaning those up should keep him out of trouble for awhile!

Either take wires off one at a  time or LABEL THEM.

And, for wires that are "hot" from the "not disconnected" end, cover the end with a piece of cheap plastic hose, hunk of old bicycle inner tube or something so it doesn't short out/arc.

Re: Alternator, Isolator or both?

Reply #11 –
Well. That didn't go well.

One of the posts on the alternator turned when Jimmy tried to loosen the bolt (the rusty looking one in the photo). The alternator is now reading 3 volts.

Can this be re-built? Big problem is that we have to be out of this campground on the 11th! Leaning towards ordering a new alternator, but have no idea what we need!

Re: Alternator, Isolator or both?

Reply #12 –
We have driven for a couple of weeks with a broken alternator. Many others have also. Run Generator to power battery charger to charge house battery, close boost switch to keep engine battery charged, duplicating what the alternator does.

Don't panic or be concerned. You will just be another of the many who have learned to drive without an alternator.

Your campground problem can be prevented by making sure all electrical connections are shinny and tight before heading out.

Re: Alternator, Isolator or both?

Reply #13 –
In terms of locating a rebuilder or new one, please let us know where you are!

But, yes there ARE some pretty simple "work arounds" that can get you on the road with a bad alternator.

You inverter/CHARGER is just that, a charger.  Generator on, the inverter/charger charges the house battery bank.

If your boost switch is working, and on, that charges the chassis battery as well.

If boost switch inoperative, merely moving the cable from one side of the boost switch and ADDING it to the other lug "ties" the two banks together.  That same "tying" can be done at the battery isolator and several other locations as well-- basically anywhere you have connections between the two battery banks in close proximity.

Re: Alternator, Isolator or both?

Reply #14 –
We are currently in Aberdeen, Mississippi. We will be here until the 11th. After that we have shorts stops until we get to Angleton, TX where we will be for the month of February.

Much to my dismay, Jimmy would like to upgrade the system.... He's in awe of what Rodger did!
I'm all for just fix it!  -Christine

Re: Alternator, Isolator or both?

Reply #15 –
Quote from: Vossx2 –

Much to my dismay, Jimmy would like to upgrade the system.... He's in awe of what Rodger did!
I'm all for just fix it!  -Christine

Just confiscate his check book!

Actually with all the corrosion on the alternator, I would also lean toward a new one rather than rebuilding that one.

Re: Alternator, Isolator or both?

Reply #16 –
Quote from: wolfe10 –
Just confiscate his check book!

Actually with all the corrosion on the alternator, I would also lean toward a new one rather than rebuilding that one.

What's our best bet? Call Foretravel and get a direct replacement shipped here? 
Is running the generator with the boost ok when our house batteries are lithium?

Re: Alternator, Isolator or both?

Reply #17 –
Quote from: Vossx2 –
Much to my dismay, Jimmy would like to upgrade the system.... He's in awe of what Rodger did!
I'm all for just fix it!  -Christine
Just to give you guys some numbers to ponder, I pulled up some recent info from the Forum.  The charging system on your coach is important, and I am all in favor of upgrading the factory components.  However, keep in mind that the original system as installed at the factory was perfectly capable of doing the intended job, and simply replacing the OEM parts is the least complicated way to refresh the system.

Your coach probably came from the factory with a Leece Neville 160A DUVAC alternator and a 3-post diode based isolator.  Photos 1, 2, and 3 below show a typical LN DUVAC alternator found on Foretravel coaches (thanks to Lt403 for the photos).  You can still buy that exact same model (brand new) today:

A0012824LC by LEECE NEVILLE - High Output Alternator

PRESTOLITE-LEECE-NEVILLE A0012824LC ALTERNATOR

Alternator - A0012824LC - Prestolite / Leece-Neville - Big Rig World

The OEM 3-post diode isolator could be replaced with a more efficient FET based model.  See below for one example:

Amazon.com: Victron Energy Argo FET Battery Isolators 200-2AC (2 Batteries...

If you need new boost and aux start solenoids, the Cole Hersee 24213 is most often recommended around here:

Amazon.com: Cole Hersee 24213 12V 200A Continuous Solenoid : Automotive

If you decide to upgrade your charging system, then the sky's the limit (both in complexity and in cost).  You can do one item at a time, or all at once.  There are several threads on the Forum dealing with this subject.  Roger's extensive electrical project report collection is one of the best, with excellent instructions and photos.

For a less ambitious upgrade example, I installed a Delco 200A alternator along with some modifications to the original charging system on our coach.  My story below:

Delco Remy 28SI Alternator Installation

Whatever you decide to do, think about the whole system before you spend any money.  You want components that are compatible with each other, and that accomplish the goals you have in mind.

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Alternator, Isolator or both?

Reply #18 –
Quote from: Vossx2 –
We are currently in Aberdeen, Mississippi. We will be here until the 11th. After that we have shorts stops until we get to Angleton, TX where we will be for the month of February.

Much to my dismay, Jimmy would like to upgrade the system.... He's in awe of what Rodger did!
I'm all for just fix it!  -Christine

That darn Roger is always making me spend my money too!!!  😂😂😂 But man they are good ideas!!


Keith

Re: Alternator, Isolator or both?

Reply #19 –
Sent you a PM.