Eliminating the DUVAC system

[z32k12]

I have an 06 Camelot with Cummins 400ISL. My Leece-Neville alternator failed in the middle of nowhere and I couldn't get one so a Delco-Remy 28SI was installed in it's place. This alternator will not work with the DUVAC system because it does not have a 6 volt output for the sensing wire; the technician installed the wire to a 12 volt connection and blew the relay in the front electrical bay. After discussion with Monaco they had me remove the relay and alt charge fuse so the light and buzzer would go out on the dash. They also let me know that I now had no protection for the alternator and that if my house batteries were low or dead there would be too much demand on the alternator and it would probably be damaged. Was told that as long as the batteries were fully charged there wouldn't be an issue.

Debating whether to go through the steps to restore DUVAC or just install a different battery isolator?

To restore DUVAC I will need to get a new Leece-Neville alternator plus find the relay. The alternator is readily available but I found the relay is obsolete. TEMCo is producing one but it won't be available until at least August.

Has anyone installed a different isolator they are happy with?

Thanks in advance,
Don

[Skip426]

Following ;

Currently having an LN with Duvac , re-built ( noisy bearings ) shop says interior of the alternator badly corroded , so it's on it's last legs.
I was looking for the Delco replacement , but no stock in Canada .

Freightliner uses a 12 volt activation wire , so I wonder if there are differences in Duvac systems .
Did your wiring on the LN have a connector like this?

[Biljol]

Magnum SBC it limits the load on the alternator to 30 amps bonus it charges the other direction also when on shore power.

https://www.magnum-dimensions.com/sm...ttery-combiner

[twinboat]

The Duvac system didn't protect anything.

It simply sensed the chassis battery voltage, eliminating any voltage drop in the wiring, and lit the dash light when the alt failed couldn't handle the load.

For others, there are Delco alternators for Duvac systems.

https://www.qualitypowerauto.com/ite...lternators.htm

[YC1]

Any chance anyone has a schematic or two??? I think this should be easy enough to address. Alternators are not complex animals in the electronics world.

Do I assume the new alternator has a built in regulator????

https://www.irv2.com/forums/f115/eng...or-529456.html

This thread may help.

[veraken]

I replaced my 160 amp Leece Neville 2824LC with a 200 amp Delco Remy 28SI. The install was fairly simple, ( I have a side radiator) except on the DR you DO NOT connect the excite wire since it is self exciting.

[twinboat]

RVs that have diode type battery isolators need battery sense wire connection.

Without it, the built in regulator can not work correctly, diodes are electric check valves, blocking the alternator from seeing battery voltage.

RVs with BIRDs, IRDs, BIMs or any other solenoid based isolation system will see the chassis voltage, and the regulator will know what to do.

If you have a volt gauge on the dash, the low voltage light isn't needed, unless you never look at your gauges.

[wolfe10]

To clarify, the primary reason for DUVAC is to allow the alternator to "compensate" for the voltage loss (turned into heat) in the old generation diode-based battery isolators. There is approximately a .7 VDC loss through the battery isolator. The sense wire/terminal allows voltage on the battery side of the isolator to control the alternator voltage.


So, for example if the alternator is designed to charge the batteries at 14.0 VDC, the alternator will put out 14.7.


If a manual battery switch (alternator B+ and chassis battery to one lug and house battery to the other lug, there is no voltage drop, so DUVAC and internally sensed voltage alternators will perform the same. I made this change on our Foretravel and it performed perfectly for the many more years we had it.


Same for other forms on "no voltage drop" options-- many based on solenoids.


Are some coach wiring schemes that are different. Sure. I would not attempt a "work around", for example, on a coach with multiplex wiring.

[RoadTrip2084]

I'm resuscitating this somewhat stale thread as the topic matches my current concern.

My '97 Monaco Dynasty has the stock Leese Neville 200A DUVAC alternator. I noticed when spinning it with my hand (belt off) that it is making a ticking sound on each rotation. It appears to be functioning still, but seems like the bearings are on their way out. I was originally thinking of getting it rebuilt, but it is rather old and corroded...

Subsequently, I have decided to replace my FLA house batteries with a 280Ah LiFePO4 (lithium) battery. I want to use a 60A DC-DC charger to charge the house battery from the FLA chassis battery when engine is running. The chassis battery would still be getting charged via the alternator.

Questions:

1. Can I simply remove the existing (original) solid-state battery isolator and battery maintainer modules from the rear electrical panel? What does the isolator actually do? I see it has inputs from the house and chassis battery, as well as the alternator. I'm assuming that it combines the two battery circuits when the alternator is active?

2. Assuming the answer to #1 is "yes", I should then be able to connect the alternator directly to the chassis battery, and then insert the DC-DC charger between the chassis and house battery connections?

3. Then I won't need DUVAC anymore, and I just replace my old crufty Leese Neville alternator with a less expensive new model without DUVAC support?

This kind of seems like a perfect plan, what a I missing?

[153stars]

The isolator was just to charge house batts off alt. Dulvac battery wire ,senses the battery voltage because diode blocks alt. from doing it through output cable.
Search Delco 28si for conversion threads as well as stumbles doing it. A couple have color diagrams. You need tach output alt. There are higher grade Delco alt. more the size and shape and cooling system of L/N alt. upper Delco even come in brushless .

[twinboat]

Good plan, but but you may be able to leave the battery maintainer in place and working.

That's there to keep the chassis battery charged while on shore power.

[CountryB]

As mentioned, you can get the Delco 28SI alternator with the "sensing wire" (it's an option, so if you order online be sure it has this terminal) and you can connect to your Duvac setup if you want. Or you can eliminate the Duvac and go with the Intellitec BigBoy (or similar) setup.

[RoadTrip2084]

My rig uses both a remote voltage sensing wire (duvac) and a wire to the tachometer.



Since I'm removing the battery isolator and will be charging the house batteries from the chassis batteries via a dc-dc charger, I shouldn't require the remote sensing wire anymore, correct?

However, I will require the tach wire still. Any idea which Delco-Remy alternator models support the tach wire?

[twinboat]

Originally Posted by RoadTrip2084

My rig uses both a remote voltage sensing wire (duvac) and a wire to the tachometer.



Attachment 352418



Since I'm removing the battery isolator and will be charging the house batteries from the chassis batteries via a dc-dc charger, I shouldn't require the remote sensing wire anymore, correct?



However, I will require the tach wire still. Any idea which Delco-Remy alternator models support the tach wire?

Check this site.

https://www.qualitypowerauto.com/cat...lternators.htm