2008 Dynasty Stafford IV: How to safely access back of 10KW Onan and Hard Starting Solution

[promontory]

Relatively new owner here, new to Monaco, living full-time in two weeks. Quick background: Previously owned 2000 Fleetwood Discovery and lived in it for two years while working in south west. My background is in electrical, but mostly power distribution and airport lighting, though some experience in electronics and have some PC and programming skills.

Changed out L16 FLA Interstate batteries today with Trojan 435aH 6V FLA. Old batteries were 4yrs old, not maintained and took 3 gallons of Distilled H2O. Please disregard how dirty the coach is at this time, on the exterior ...

I have been searching posts and reading the forum, which has been invaluable! I have a couple of questions:

1. How do y'all safely get underneath your coach? For example, I'd like to get to the back side of the generator to inspect and clean the battery connections, without tunneling under the coach. Is there an easier, safer way to do this on a gravel lot aka my driveway?

2. I have the infamous 10KW Onan hard start issue, which means the AGS does not always work. Utility power in my neck of the woods is not always reliable. My goal is to get the generator cranking as it should, and the AGS thus working as it should. Other than generator start cables (12V), where should I be looking next?

Thank you in advance for your replies, and also for directing me to any posts I've missed that may have already covered this topic!

 

Edited April 11 by promontory
Thread posted somehow before I completed writing it.

[promontory]

Youtube Video from 2020 when coach was sold in the past, showing generator starting hard.

Did some OSINT on our coach and found two videos from 2020 when the coach was sold to the previous owner's. We are the third owner's of the bus, I believe. Anyway, the video link above shows the tech starting the generator. It starts exactly the same way now. As others have noted about their's in previous posts, when the engine is Cummins ISM is running, the genny fires right up. Is this the infamous 'hard start' issue that I've been reading about on this forum? Any input as to where to start would be appreciated. My thinking is:

1. Clean up all battery connections at generator and house buss (pos and neg)
2. Look at voltage drop on long battery cables.
   1. Cables seem to be #2. Wiring diagrams show 2/0. I am thinking that the cables might be too small
   2. If too small, should I run new cables back to house battery buss?
   3. I see that some have installed separate battery for starting genny.
      1. Seems overly complicated to me, but how do you charge that battery and where did you mount it? Are you happy with that arrangement? What size battery for the 10KW Onan diesel?

[Tazmanian Martje]

Do you have hydraulic jacks or air leveling?  I unfortunately only have air leveling. What I do is raise the coach full then crawl under both front and back and put 8 hardwood blocks on the between the frame and house frame and then lower the house frame onto the blocks.  Open out your genny.  Now you have room to work behind it.  That is what I did on our 2003 Signature.  We took the fuel pump and moved back to the fuel compartment( pumps are meant to push the fuel not pull so much) . Beautifully fixed our burning out fuel pumps.  Also had plenty of room to replace the air pump. 

Now I want a dedicated bloody battery to start the genny.

[Tom Cherry]

22 minutes ago, Tazmanian Martje said:

Do you have hydraulic jacks or air leveling?  I unfortunately only have air leveling. What I do is raise the coach full then crawl under both front and back and put 8 hardwood blocks on the between the frame and house frame and then lower the house frame onto the blocks.  Open out your genny.  Now you have room to work behind it.  That is what I did on our 2003 Signature.  We took the fuel pump and moved back to the fuel compartment( pumps are meant to push the fuel not pull so much) . Beautifully fixed our burning out fuel pumps.  Also had plenty of room to replace the air pump. 

Now I want a dedicated bloody battery to start the genny.

Check the size of the cables going to the Genny.  Been discussed and beat to death.  If you don’t have at least 2/0. (00j cables….then that is the issue.  Goes for the positive and ground.  Many folks that added a third or dedicated battery….upgraded….or did the common sense thing.  They have glowing reports. But, in reality, their cables were #2 AWG.  MONACO, for reasons unknown to the gods, would run 4/0 (0000) cables to the FRONT and there is a Stud with a 4/0 cable…..but then undersized the cables to the starting studs on the Genny….both sides. Even a 2/0 would or does work.

Now, only a small percentage have genny starting issues.  But, based on ambient…they have isdues.  Not denying that.  But few do the proper testing and compare the battery, measuring at the bank, UNDER LOAD.  Record that.  Then, repeat….measure the voltage on the genny terminal (to Ground).  Finally, repeat again on the Rear Genny terminals. IF there is more, underload or when starting, than a 0.1 - 0.2 VDC DROP….then the “cabling” and such….and there must be an issue internally with the starter.  BUT…more than that…a high resistance contact or connection….that assumes that the entire run is at least 2/0.  The specs on #2 AWG will not carry enough current for a Genny in cold weather.

This has been tested and Monaco’s cheapness catches some. Others in mostly warm climates are marginal, but get by. A WHOLE LOT EASIER & CHEAPER than just putting a not needed battery.

Real world and proved by testing….#2 AWG ain’t gonna cut it.  If you run car jumper cables from the positive stud up front where the genny cable is and a good ground up there….and attach to the rear genny terminals….that demonstrates at.  Even small AWG (USUALLY #2) will supplement the cranking amperage.

Home audio enthusiasts have done this for years.  You run TWO sets or two speaker cables from the amp/receiver to each speaker.  One 2 wire speaker cable…twist the leads.  Use that for “positive”.  Likewise use the other wire, twisted leads, on the negative.  The English call it “BiWiring”… sound is awesome.  No voltage drop….DUH!

[Frank McElroy]

On 4/10/2024 at 10:27 PM, promontory said:

Relatively new owner here, new to Monaco, living full-time in two weeks. Quick background: Previously owned 2000 Fleetwood Discovery and lived in it for two years while working in south west. My background is in electrical, but mostly power distribution and airport lighting, though some experience in electronics and have some PC and programming skills.

Changed out L16 FLA Interstate batteries today with Trojan 435aH 6V FLA. Old batteries were 4yrs old, not maintained and took 3 gallons of Distilled H2O. Please disregard how dirty the coach is at this time, on the exterior ...

I have been searching posts and reading the forum, which has been invaluable! I have a couple of questions:

1. How do y'all safely get underneath your coach? For example, I'd like to get to the back side of the generator to inspect and clean the battery connections, without tunneling under the coach. Is there an easier, safer way to do this on a gravel lot aka my driveway?

2. I have the infamous 10KW Onan hard start issue, which means the AGS does not always work. Utility power in my neck of the woods is not always reliable. My goal is to get the generator cranking as it should, and the AGS thus working as it should. Other than generator start cables (12V), where should I be looking next?

Thank you in advance for your replies, and also for directing me to any posts I've missed that may have already covered this topic!

 

First, it's important to know if you have a standard or Kongsberg chassis multiplex coach.  2008 standard chassis coaches started the generator form the chassis batteries.  2008 Kongsberg chassis multiplex coaches started the generator form the house batteries.  The other issue is that the cable from the front run bay (FRB) needs to be 4/0 not the smaller OEM 2 gauge.  If your coach is starting the generator for the chassis batteries, the generator needs to run long enough to recharge the house batteries and THEN when BigBoy kicks in to recharge the chassis batteries.

[promontory]

@Frank McElroy - Thank you for your input. I have the Intellitec, standard chassis multiplex coach. I definately either need to run heavier guage cable from the chassis batteries to the generator, or calc the kcmil surface area of running a parallel of each #2AWG.

[Tom Cherry]

Frank and I discussed offline this morning.  Here is the print of the 2008 Dynasty.  That is also what was commonly (NOW Monaco never was consistent) in how they did things....but generally speaking, after reading and doing a lot of research on this, MOST of the posters with Genny Starting (off Chassis) issues, per THEIR individual prints, DID have the infamous #2 AWG cabling.  A FIASCO.

I did my own analysis....using some data that folks had posted after doing some clamp on AMP measuring and such.  Frank, as usual, is absolutely correct.  It DOES take a WELL CHARGED Chassis Battery to start the Genny...  BUT, the voltage drop due to the #2 AWG cable is also, when the Chassis might not be at peak, in my opinion...the culprit...

It is ALSO the easiest to fix.  Folks have run AUX batteries....many did a GREAT JOB.  The MAJORITY of them ran a 2/0 Cable from the up front Battery and rave about how it works.  OK....since there is also a 4/0 cable providing the Chassis Power...  my theory...  Put in a 2/0 cable.  YES, one can run a 4/0.  Is that OVERKILL?  I don't know and we have, me included, folks of the MINDSET...

if X is better and will do the job....then, BY GOD....I'm going to solve this forever...and use 2X.  SO....that is a debate that can rage.

Assuming all the ground connections on the Banks in the rear (stud grounds) and the upfront ones (to the Genny) are clean and good...then I would start off with 2/0 NEW cables to the Genny from the existing Ground stud and the 4/0 Stud.  BUT...as they say... Knock yourself out and go with 4/0...if that is your mindset...  LOL...

Jonathan....you can run the calculations...but you will get (memory) at least 75% MORE (based on my guestimated length) current from a 2/0 than a #2 AWG).  Again...long time ago, but it was easy to use the online calculator and see the max current.... if you publish the results...then we will all have the numbers...

BUT.. I think that most would benefit from the 2/0...  NOW, caveat.  Live in a colder climate or your Chassis are not top drawer.  Certainly a 4/0 will do the trick.  After all, it starts that big puppy in the rear.  

Hope this explains the logic and why the reason is simply a cabling goof..  WORKS OK...as long as in mild climates and GREAT starting chassis...but change one...and then problems may (OK HAVE) occurred...

Let us know what you decide to do and how it works.

38070173 High Current Low Voltage 2008 Dynasty Print.pdf

[Tom Cherry]

UPDATE.  Jonathan and Frank and I have been exchanging emails and both did some checking.  I also did some "Voltage Drop" or Ampacity loss calculations....and then we bounced it around.  SO...here goes....

What is the approximate AMPS needed to crank the Generator (presumably a 10KW).... Had researched that before...and did it again and found this.  MOST informative and definitive.  The poster had a 10KW in 2009 or so Camelot.  NOW understand, that the cables for the Camelot are the same for all Genny's - 8 or 10KW. SO, what the individual did...PUT IN AN UPFRONT Battery...and then ran the test.  FWIW, there is a 125 Amp fuse in the House Buss in the rear...dedicated to the Genny and a 1/0 (0) cable...not the best....but HEY...it is what it is...as well as demonstrates...  MONACO did not know diddly squat about some basic electrical facts...Voltage Drop and Cable Size and Cable Length Runs....so here is the WHAT IS CRANKING....from a good, up FRONT source.  BTW, I have NEVER read about the 125 Amp Bussmann ANL Ignition Proof Fuse BLOWING...

• The 12V+ lead is 4/0 wire 72" long. The ground wire is 48" connected to the frame.
• At the start of the test, the battery was fully charged @ 12.7 Volts.
• Outside temperature was 15 C.
• During the prestart step the generator drew 6.0 Amps, with very little voltage drop off.
• When the starter cranked, the amps peaked at 207 Amps, then settled at 197 Amps until the generator fired.
• The battery supply voltage (at the terminals) dropped from 12.6 Volts to 10.8 Volts.
• Immediately after starting, the battery recovered to 12.3 Volts.

OK....NOTE the last comment.  ONE of the issues, as reported by many, with UP FRONT AUX Genny Batteries....HOW TO CHARGE.  Some had DC/DC chargers and others Trickle AC chargers (powered from Cabin) and others have run JUMPERS....

OK...NEXT UP.... AGAIN.  This is for two similar 2008 Dynasty's...as Frank and Jonathan have virtually the same MH as far as the wiring goes.  The ISSUE of having POOR starting issues with the 10/12.5 KW can be summarized into the following.

• The Chassis Battery, usually will start the engine fine....but is NOT FULLY CHARGED....so, when you push the cable run and the way MONACO wired it....there is GONNA be an issue.  NOT EVERYONE has this....it sort of varies and pops up....way to frequently.
• The Cabling running to the Generator is INADEQUATE.  That is easily understood on the drawing.  NOTE... there is a #2 AWG cable running to the Genny.  Overall length is estimated.  The Positive might be 15 Ft and the Negative might be 6 Ft.  FOR Calculations....used 12 Feet.  Frank agreed this was logical. NOW, REMEMBER...from the DRAWING....there is a 4/0 (0000) cable running to the front.  Used 50 Ft., which is probably over stated...but for the sake of being overly conservative....that is what was used.
• FINALLY...the Ambient conditions are UGLY.  We have had folks that were cranking in sub freezing...possibly in the single digits...  NOW....Jonathan ran some tests....MORE LATER...

OK...  From Southwire, used their Calculator and used the following logic and parameters.

• 50 Feet 4/0 (0000) cable will lose 8.5% over a 50 ft run.  Therefore a 12.7 VDC battery will deliver 11.6 VDC to the front stud.
• OK...now BASED on that Front Stud voltage of 11.6....what is the Voltage DROP for "12 ft" of each of the three following cables.  Monaco OEM #2 AWG; 2/0 (00) and 4/0 (0000) cables.  See the table from my Excel Spread sheet below.  RED is BAD....Yellow is CAUTION and GREEN IS "DRIVE ON".  

OK....what we all, generally agreed on...and Jonathan also has an electrical background.  The #2 AWG ain't cuttin' it.  DUH.  We have MORE statements here about that and they all agree.  OK... NOW, we know why.  SO....what is the solution?  Depends on how close, CLOSE is...for your own SAFETY factor versus "YEAH...That'll WORK".

I have been a proponent of 2/0 (00) as CLOSE ENOUGH.  I think that I erred on the conservative side...so the "Needed & Measured" required Cranking Amps (also posted elsewhere and I had read it at least 2 or 3 times in other places by others that seemed to be "CREDIBLE".  AND dealing with 2/0, personal experience, is a bit easier that 4/0.  Frank and I, as many do, have Hydraulic Crimpers...which we carry.  I carry some 4/0 connectors and shrink wrap (Frank recommends the shrink wrap with a heat settable adhesive...good idea)...so if I ever lose a connection, don't have to mess with pulling the cable and finding a Welding Shop.  MY EXPERIENCE.  Most NAPA shops that make cables don't even have 1/0 and they rarely have a HYDRAULIC crimper.  Welding shops are better, but they don't have the proper HOLE (terminal diameter) cables...so I ordered two spares...

OK...that's it.  Frank's vote...NOT SURPRISINGLY... LOL.... is 4/0.  Can't argue there....

OK...after all this was passed back and forth, Jonathan also ran some tests.  The Chassis batteries spin the ISM engine and it cranks right up.  NO OMG Hesitation.

NOW, when the Engine was running, the 10KW turned over quickly....NO ISSUES.  BUT, when just on the Chassis....  Slow, starts...sometimes....but other times... NOT.  He was about to invest in NEW Chassis batteries, but after our emails...  He is replacing a "lost in a fire" hydraulic crimper and will make up 2/0 (00) cables....and will match them in length and also stud (Hole size) to the OEM's and will let us know...

Bottom LINE.  The OEM goof is the REAL issue.  Adding an upfront battery is a solution that some prefer...and we, and me, often decide to "FIX IT" realizing that OVERKILL might be more appropriate and added to the FIX IT.  

The numbers don't lie.  There is an issue with the #2 AWG.  I had stated that just switching to 2/0 (00) would add 50 - 75% MORE available amps.  That was from "quick matchbook cover" scribbling.  This time, I think I approached it logically.  NOW the Southwire calculator MIGHT not give the same numbers as others....but this logic is what I have used on long AC runs for my well pump and Frank also did the same and we both agreed that my cable size was OK and all is well.

Hope this helps clear it up.

Will wait for Jonathan to respond.  Don't know if Frank or Jonathan will chime in and comment...this is the gist I got from all the emails....and there were close to 10 and some were long.  

Might be a while...but I think he is going to be OK.  

2008 Dynasty - Voltage Drop Calculations - Generator Start Cable Calculations.pdf 38070173 (Schematic, High Current,Low Voltage).pdf

[96 EVO]

22 hours ago, Tom Cherry said:

  BTW, I have NEVER read about the 125 Amp Bussmann ANL Ignition Proof Fuse BLOWING...

•  

 

I've blown mine several times!

Probably a couple while wired from the factory from the house bank, and a couple more times after switching to the chassis bank.

I carry a 10 pack of spares!

[Tom Cherry]

44 minutes ago, 96 EVO said:

I've blown mine several times!

Probably a couple while wired from the factory from the house bank, and a couple more times after switching to the chassis bank.

I carry a 10 pack of spares!

OK....I stand corrected.  I have several other friends, current and USED TO OWN, Camelot owners...  Most were 2009, but at least one 2008.

They NEVER blew or mentioned the fuse issue.

NOW, from someone that has been there and DONE THAT...  I finally, after over 10 years of use....and chasing down what was causing my 200 Amp ANL on the hydraulic....the EVIL CAUSE.  I have (gonna fix it once out of storage) a cranky Blue Seas House Bank switch.  It will be ZERO volts across the studs...but drive it around the block...and it will loose, on a VOM...  half a volt.  ALL the LUGS ARE TIGHT.  It just has an internal failure and has an intermittent High Resistance Connection.  I did FULL LOAD voltage testing all the way back from the Hydraulic system to the batteries....TWICE...  BUT, that was when the switch was "GEE....I'm OK". I was messing around a while back and just put the VOM on the switch.  BINGO...it was in its "I'm GONNA BE MEAN" days...

SO, it will be replaced.

OK...ASSUME you have 1/0 Cable....that is closer to 150 Amps.  I personally would swap that out for a Bussman ANL 150 A Ignition Proof Fuse.  I can TELL YOU....from experience with the 200 Amp ANL fuses....they AIN'T ALL BUILT the same.  I had some cheaper ones.  They blew like Pop Corn.  I replaced the third one with the REAL OEM BUSSMANN ANL Ignition Proof...It is STILL working...

SO, the SURGE capacity of the off brands and cheaper are, based on limited experience....WAY LESS.

NOW...if you UPGRADE to the 150 A, that might get you some relief.  Since this is a STARTING load...and NOT a continuous FLA load, there is to me...NO DANGER using the 150A.  Most charts rate the 1/0 cable at 145....so 150 is close....based on the load characteristics.

NOW....  THE BEST FIX... assuming you aren't a GLUTTON for Punishment and want to custom fab a battery rack and such.... and I WOULD DO THIS IN A HEARTBEAT...

Order the following from Amazon... Blue Sea Systems 6007 m-Series Battery Switch Selector 4 Position, Red

Now, that is what I installed for my Hydraulic Pump.  You have TWO 200 Amp 4/0 cables running up front.  I tapped into BOTH of them on the Studs.  They are Battery 1 and Battery 2 on the BS Switch.  THE OUTPUT of the switch goes to the 80 A CB for the Hydraulic pump.  I am using Battery 2 or the CHASSIS for the interim....but after I swap the Blue Seas defective House Switch...I'll probably go BACK to the HOUSE....as designed for the slides.

You can then recable to the Genny.  PERSONALLY, I'd only use 2/0 (00) Cables.  BUT, you could, but the terminals are harder to work with, use 4/0 (0000)...  The 2/0 (00) is rated for 175 amps.  Then the 200 Amp fuses would be great.  I'm willing to wager that your starting issues will be over.  ONE WAY TO TEST..  Use a pair of Jumper Cables and go from the Chassis Positive to the Genny Positive and run a good Ground also.

Therefore, you could USE the BAT 1 PLUS BAT 2 position...and that would pump out a screaming 400 amps.  You only need 200....so even with voltage drops....both banks powering the starter should make that starter spin like a Dreidel....  NOW, as you KNOW....using the BAT 1 & BAT 2 position....WILL JUMPER, just like the Big Boy, both banks....so you could (would...should) use it sparingly and set back to BAT 1 or BAT 2.  No complex theories here.  It works...and mine is great.  The switch fit nicely on the left front panel on a block of wood...I THINK I posted pictures.

Good Luck...