Preventing DUVAC alternator problems

[Guest Ray Davis]

1 hour ago, waterskier_1 said:

While a DUVAC alternator may not be required for voltage sense and regulation, you will still need an alternator which has AC taps which drive both the tach (on your coach) and the ALT-FAIL circuitry for warning of a failing alternator. 

  - Rick N 

Does that apply on a 2000 yr model?  Is that a computer ( ECM ) engine?   I think it is.   If it is an electronic engine doesn't the tach get its info from the ECM?   I'm asking because I'm not sure

[Bjohnsonmn]

10 hours ago, Ray Davis said:

Does that apply on a 2000 yr model?  Is that a computer ( ECM ) engine?   I think it is.   If it is an electronic engine doesn't the tach get its info from the ECM?   I'm asking because I'm not sure

The wiring schematic shows AC taps for the Tach and Alt-Fail. Thinking about that, it confirms my suspicion that the wiggly + Battery post on the back of mine is the issue!

[Bjohnsonmn]

I noticed that the Delco 28SI was listed as a suitable alternative for the Leece DUVAC.

Questions for someone who has made the swap:

1. Did you reuse the DUVAC (20amp fused) wire as the new alt-sense wire?

2. Which version did you buy? The long or short swing, the 160amp or the 200amp?

3. Any oddities pop up that are in your "That's just how it is" book?

Thanks!

[Dr4Film]

Brad, you may want to reach out to Van Williams here. If I remember correctly, he may have installed a Delco 28SI on his Cummins engine in his Dynasty.

[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).  On the DR you don't connect the excite wire since it is self exciting. I purchased mine with a extra pulley wheel at:

https://www.qualitypowerauto.com/catalog.php?category=139

I had my old LN rebuilt and carry it as a spare.

[jimc99999]

On 6/13/2022 at 8:41 AM, Bjohnsonmn said:

I noticed that the Delco 28SI was listed as a suitable alternative for the Leece DUVAC.

Questions for someone who has made the swap:

1. Did you reuse the DUVAC (20amp fused) wire as the new alt-sense wire?

2. Which version did you buy? The long or short swing, the 160amp or the 200amp?

3. Any oddities pop up that are in your "That's just how it is" book?

Thanks!

On my 97 Windsor with C8.3, I had to install the long cage alternator. The short cage alternator I tried (vendor stock issues) had clearance issues on the top mount. It may have required a different belt and possibly a different bottom mounting bar to clear the block. 
 

I was unable to find any solid info to indicate the amperage rating of the original alternator. I was going to install a 170A, but the long cage version didn’t come on the delivery truck so I went with the 210 they had in stock rather than spend another couple hours driving there and back another day. 
 

The new alternator is self exciting, no voltage sense needed. It does require 1000 rpm to excite and the old 8.3 sometimes doesn’t hit that on startup and requires a little rev to get the alternator going. If the alternator is not excited the tach doesn’t work either and the alt charge light is on. 

10 minutes ago, veraken said:

I had my old LN rebuilt and carry it as a spare.

Where did you have it rebuilt? I haven’t found anywhere local and figured shipping both ways plus rebuild was probably cost prohibitive compared to just getting another at a shop when necessary.

Edited June 14, 2022 by jimc99999

[veraken]

I was able to find someone local - Columbia, SC

[Bjohnsonmn]

1 hour ago, veraken said:

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).  On the DR you don't connect the excite wire since it is self exciting. I purchased mine with a extra pulley wheel at:

https://www.qualitypowerauto.com/catalog.php?category=139

I had my old LN rebuilt and carry it as a spare.

Did you have strange issues at idle? Jim mentioned that that his alt fail light came on due to low idle speeds...

[jimc99999]

6 minutes ago, Bjohnsonmn said:

Did you have strange issues at idle? Jim mentioned that that his alt fail light came on due to low idle speeds...

No, idle is fine, once the alternator is excited it stays active while it continues to spin. But occasionally it doesn’t spin high enough on startup to excite the alternator, so the alternator won’t start working until you rev the engine. 

[MHRookie]

Are more people switching to the ML-ACR unit when their Leece Neville fails?  Seems like an improvement all the way around for the system.

[Dr4Film]

Kurt, I think people are switching to the ML-ACR due to its charging abilities and its simplicity versus the convoluted charging systems that Monaco had installed, not necessarily because of the alternator.

Edited June 14, 2022 by Dr4Film

[Ivan K]

I would switch if my isolator fails. The LN alternator is just as rebuildable as any other so that alone would not be a reason for me.

[Bjohnsonmn]

2 hours ago, MHRookie said:

Are more people switching to the ML-ACR unit when their Leece Neville fails?  Seems like an improvement all the way around for the system.

My change over is spurred by the alternator going wonky, but the isolator was removed because it wouldn't work well with my LiFePO4 house battery setup. I am going to a DC-DC charger to charge the house on the road and a to be determined thing to trickle the chassis while we are parked.

[veraken]

3 hours ago, Bjohnsonmn said:

Did you have strange issues at idle? Jim mentioned that that his alt fail light came on due to low idle speeds...

Don't remember having problems at idle.  I noticed that my batteries were not being charged when going down the road.  Ran my generator to keep it charged until I got home and could make the change.

[Bjohnsonmn]

It would be nice to know the system voltage... but the ammeter in the dash pegs to 18v and always has!

[waterskier_1]

On 6/12/2022 at 7:35 PM, Ray Davis said:

Does that apply on a 2000 yr model?  Is that a computer ( ECM ) engine?   I think it is.   If it is an electronic engine doesn't the tach get its info from the ECM?   I'm asking because I'm not sure

I think so.  My 2000 Windsor drawings don't show the alternator connections (that I can find).  But, 2000 Diplomat does still use the AC Tap for both the ALT-FAIL circuit and the Tach.  I believe that Cummins incorporated the Electronic Controls on their engines in 1998.  That would be the engine year, not the coach model year.  When they changed from the mechanical engine, they named the new 8.3 (for example) from C8.3 to ISC.  If it is an ISC (or ISM or ISL or ISX, etc.) then it is electronic control.  I'm just not sure when Monaco converter from using the alternator AC tap to drive the Tach to the ECM.  By 2003 the Dynasty, Exec, and Sig used the ECM for the Tach.  I don't have wiring diagrams for the Knight, Dip, Windsor, etc., but think they do too.

  -Rick N.

[Bjohnsonmn]

Here's the relevant snap shots from my wiring diagrams:

 

This is from my 2000 Windsor 32PB

[waterskier_1]

Brad, the second diagram (with the Hamstar relay at the bottom, shows the ALT-FAIL wire at "S5" continues to the right and is labeled "TACH".  That wire continues on to the TACH on the dash. 

  - Rick N 

[Bjohnsonmn]

1 minute ago, waterskier_1 said:

Brad, the second diagram (with the Hamstar relay at the bottom, shows the ALT-FAIL wire at "S5" continues to the right and is labeled "TACH".  That wire continues on to the TACH on the dash. 

  - Rick N 

I think you mean the alt relay wire. As I read the diagram, the relay at the bottom that drives the Alt-Fail light is triggered when there is not a charge across the Alt-Relay wire.

[vanwill52]

My experience may be anecdotal, but I expected my tach signal to come from the ECM ouput labeled "Tach Ouput".   On my coach IT DOES NOT.  IT COMES FROM THE ALTERNATOR, CRAZY AS THAT SOUNDS.  Disconnect the alternator "tach" ouput and your tach goes dead.

[engine103]

Grampy OG. Ken, when you complete your installation could you please post a picture, would appreciate it. Jim

[Bighoud1963]

very interesting and very helpfull.  But i am limited on RV électric.

Two questions ?

1-  If i send pic is someone can help me to make these change?

2- Can someone can take time to tell me what each parts are on these pics.?

if i know what each relay or sélénoid fonction is, i will well understand my électrical system

 

can someone help me ?

 

thanks

[Dr4Film]

Vanwill is the most knowledgeable on this issue. He is our resident expert on many systems within our coaches.

[jacwjames]

10 hours ago, Bighoud1963 said:

very interesting and very helpfull.  But i am limited on RV électric.

Two questions ?

1-  If i send pic is someone can help me to make these change?

2- Can someone can take time to tell me what each parts are on these pics.?

if i know what each relay or sélénoid fonction is, i will well understand my électrical system

 

can someone help me ?

 

thanks

Can you take a picture of the passenger side rear electrical bay and post it here.   If it is similar to my 2002 Windsor I should be able to help you out

Pouvez-vous prendre une photo de la baie électrique arrière côté passager et la poster ici. 

Si c'est similaire à mon Windsor 2002, je devrais pouvoir vous aider

 

[Bjohnsonmn]

1 hour ago, jacwjames said:

Can you take a picture of the passenger side rear electrical bay and post it here.   If it is similar to my 2002 Windsor I should be able to help you out

Pouvez-vous prendre une photo de la baie électrique arrière côté passager et la poster ici. 

Si c'est similaire à mon Windsor 2002, je devrais pouvoir vous aider

 

Your photo looks nearly exactly how ours looked before I started our reconfiguration. (Though we still had a large solenoid connecting the house and chassis with a relay delay type device in the space to the left of where this photo was taken).

With our conversion to LiFePO4 batteries and the fact that it was time for a new alternator (The positive post on the alternator itself was broken and in the process of making a new metal alloy inside the alternator), we have completely isolated the two systems. I do have a DC-DC charger from Victron that I will wire in if we find that we want to take advantage of the chassis charging while driving, though with more than 400w of brand new solar on the roof, I am hoping that will help. The generator could also help in those situations.

I am nearly done with the full conversion of our 2000 Windsor 32PB (@adventureswithloaf on instagram if you want to see progress photos that my wife is posting). Once it is complete, I plan to do a write up on the process in a way that others can learn from our project including what you gain, lose, and benefit from in our approach. The 32PB is the most space constrained of the models that we are aware of given it is only 32ish feet long and has no slides. We had to get creative.

To the person looking for help: What are your goals? Is it to eliminate the DUVAC? Is it to clean it up? Is it to just be able to keep it going as is? Each of those paths will have different advice associated with it.