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!