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08-21-2017, 07:04 PM
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#1
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Senior Member
Fleetwood Owners Club Spartan Chassis
Join Date: Feb 2011
Location: Florence, AZ
Posts: 149
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Altenator Problems
I have a 96 Windsor. My alternator quit. So I installed a new one, I also installed a new chassis battery. I drove about 30 minutes and the new one quit. I left it set over night and in the morning it worked for about 40 minutes and quit again. I had my old alternator rebuilt so I installed it. I drove one hour and stopped for lunch and everything seemed fine. After lunch I drove 45 minutes back to my storage spot and as I drove in my rebuilt alternator quit charging, Anyone aware of anything else in the charging system that would cause the alternators to quit? I have trouble believing both alternators are faulty. ( My house batteries are also new,)
Thanks,
Ron D.
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08-21-2017, 07:49 PM
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#2
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Senior Member
Monaco Owners Club
Join Date: Jun 2014
Posts: 14,588
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Not sure on your vintage coach but on my coach the original alternator, a Leece Neville, had a DUVAC system, no idea what this means but know that it is not compatible with most other systems. If you installed a new alternator it may have played havoc with your system and when you installed the rebuilt original it may not work.
On my system there is a fuse in the rear passenger side electrical compartment labeled Duvac, you may check to see if this fuse is blown.
__________________
Jim J
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi
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08-22-2017, 09:57 AM
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#3
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Senior Member
Join Date: Nov 2014
Posts: 1,671
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__________________
2004 HR Navagator 500 ISM
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08-23-2017, 05:48 AM
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#4
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Senior Member
Join Date: May 2014
Posts: 868
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Check your isolator
__________________
Peter
36 ft. 99 U320 foretravel 36 ft. 98 Dynasty
98 Suzuki Sidekick Sport 4 door
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08-23-2017, 09:32 AM
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#5
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Senior Member
Fleetwood Owners Club Spartan Chassis
Join Date: Feb 2011
Location: Florence, AZ
Posts: 149
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Altinator problems
Thanks for your replies. My coach is a 96 Windsor. How would I know if I have a Duvac system and what does it do? How do you check the isolator?
Thanks,
Ron D
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08-25-2017, 01:45 PM
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#6
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Senior Member
Join Date: Oct 2010
Posts: 1,460
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If it has a single small wire coming out of the voltage regulator block that's the wire required to get a self-exciting alternator to put out power if you have a diode isolator. See my post from yesterday to get an idea of what I'm dealing with.
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08-27-2017, 09:22 PM
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#7
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Registered User
Join Date: Sep 2011
Posts: 1,510
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Ron, you are wise to think that TWO alternators (of different design) failing in a similar manner is TOO MUCH of a coincidence. Myron, (YC1) is extremely knowledgeable about the DUVAC systems, and I hope he chimes in here. Basically, when a solid-state isolator is involved in a charging system, the alternator MUST have a "remote sensing" wire that signals the alternator what the voltage actually is AT THE BATTERY. The isolator injects a .70 voltage drop, and small as that seems, it is enough to totally change the charging characteristics necessary to maintain the batteries at total charge.
That remote sensing connection is the single reason that so many folks have untold problems when they replace their (unreasonably expensive--$750) Leece-Neville alternator with a much cheaper, but higher capacity Delco SI series that is self-excited and internally regulated, but lacks the DUVAC remote sensing wire. Later Monaco's replaced the isolator with a failure-prone BIRD relay system which IMHO was even worse than the SS isolator.
Luckily, the isolator on my 2000 Dynasty has not failed, but I have already purchased what I need to replace the entire isolator system, and prepare the system for a cheap and trouble-free alternator replacement whenever it becomes necessary. It is a Blue Sea ML-ACR system. Approx $200. A knowledgeable friend (pwhittle) installed that on his 94 Sig when his alternator failed, and the cost of the Blue Sea ML-ACR AND a new Delco SI series alternator was less than replacing the existing LN alternator with a new unit.
Very few auto (and even RV) techs understand the voltage sensing requirements imposed by a SS isolator system. From personal experience, I can tell you that the remote sensing wire must go DIRECTLY from the terminal on the DUVAC alternator to the chassis battery terminal. On my 93 Dynasty, a tech had decided that attaching it to the back of the main cut-off switch was "good enough", but he was wrong. After many hours of trouble-shooting, I finally checked the voltage drop from the cut-off switch to the battery post. When the alternator is charging at a high rate, that voltage drop was as much as .50 Volts. That caused the alternator to turn-on/turn-off at about a one second interval.
I know this is a long post, but to summarize, if you decide to repair your existing system with SS isolator, your voltage-sensing wire MUST be connected correctly, and MUST go directly to the chassis battery without any interconnections along its path. OTOH, should you find yourself wishing you were not always needing a high-dollar alternator each time you have a failure, consider converting to the Blue Sea (or something similar) system. BTW, the Blue Sea system has a built-in capability to CHOOSE which battery bank you are charging, and also has an internal "battery boost" feature to combine batteries when you need the extra capacity for starting.
And as a somewhat peripheral note, most knowledgeable folks in the Monaco universe have concluded that many alternator failures are the result of the fact that the Leece-Neville alternators did not have great current-limiting circuitry, and when either chassis or coach batteries (or both) were low, the alternator would charge above its continuous rating, causing it to overheat. Many alternator failures were the result of overheating causing the regulator circuitry to permanently fail. For that reason, it is good advice to start your genny and let the inverter's sophisticated circuitry charge your batteries when they are very low. If you start the drive engine, the alternator will be the only thing charging the batteries.
Should you wish to hear from folks more knowledgeable than myself, contact YC1 or pwhittle (who installed the Blue Sea system). Your problem is more simple than you might think, but there is an ocean of misinformation out there about DUVAC alternator problems.
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08-28-2017, 03:33 PM
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#8
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Senior Member
Fleetwood Owners Club Spartan Chassis
Join Date: Feb 2011
Location: Florence, AZ
Posts: 149
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altenator problems
Thanks for all the helpful replies.
I replaced my old alternator with a new one, the same exact part number and model as the old one (LN 2824 LC $360 at the local Freightliner dealership.) which ran 100,000 miles.
It has 5 terminals on the rear. Large ground. large positive to batteries. Two smaller terminals, each with a wire attached from loom. On is marked ignition. one is marked remote source. Then three smaller terminals, one with a smaller wire attached which I assume drives the tach,
I do not have a chassis wiring diagram . Anyone have one?
Thanks,
Ron D
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08-30-2017, 04:36 AM
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#9
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Senior Member
Join Date: Oct 2010
Posts: 1,460
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On a Delco 28SI there are TWO wires required for optimum operation. The sense wire that causes the alternator to compensate for the isolator voltage drop AND the ignition wire, which is required to get the alternator to self excite. The ignition wire can go to the alternator or it can go to the 4th post on a 4 post isolator, but it MUST be switched. If not, the chassis batteries will discharge into the house batteries via the alternator. See my post elsewhere on this forum for the entire horrific story.
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08-30-2017, 11:06 AM
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#10
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Member
Join Date: Mar 2015
Posts: 64
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Vanilla nailed it; Duvac was developed by L/N and is used on diode iso systems.
If you have a Duvac, a Duvac unit must be used.
My Alternator failed from attempting to charge low coach batts.
Had it rebuilt, and it failed again.
BUT what failed was the regulator, causing the charge voltage to rise to 17+v
This can burn out alot of electronics in the coach.
I unplugged the 3 wire plug to shut it down.
Then used the gen.
The chassis bat charged from the Xantrex.
The problem seems to be with the reg that will come from the rebuilder.
The OEM 100650 L/N or a L/N direct replacement had to be used.
The replacement alt's I used had cheap import units that failed from heat from the engine on long pulls.
Long hot pulls finished off the reg, so I called Prestolite and Mark set me strait on
the correct reg.
The reg must be stable up to 250.
If it happens again I will convert to a remote reg. They are avail for Duvac inst.
Presolite is the Worldwide co for L/N.
Amazing tech support. I called and hung up and Mark called me back !
I now don't do these thing:
Charge dead bat with the engine. Use the gen.
Don't run the microwave with the engine running.
Use the BIG BOY continuously to charge chassis batt.
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08-31-2017, 10:12 AM
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#11
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Senior Member
Join Date: Oct 2010
Posts: 1,460
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