Rewiring Generator to Chassis battery bank

[Steve P]

After a recent lengthy discussion on boondocking, I have determined that my generator uses the house batteries for starting.  I would like to rewire it to start on the chassis battery bank.

I think the connections are in either the driver run bay or the passenger side battery bay.

How do I determine which?  Should I submit pics of both bays? Procedurally, I'm sure I need to shut off bypass switches or disconnect cables, but I'm not sure of which ones, in what order, etc.

Thanks in advance for any advice or pointers. 

Steve

[96 EVO]

33 minutes ago, Steve P said:

 

I think the connections are in either the driver run bay or the passenger side battery bay.

How do I determine which?  Should I submit pics of both bays? 

Yes!

The rear run bay wiring schematic from your owners manual would be even better!

Edited October 27, 2023 by 96 EVO

[georgecederholm]

11 hours ago, Steve P said:

After a recent lengthy discussion on boondocking, I have determined that my generator uses the house batteries for starting.  I would like to rewire it to start on the chassis battery bank.

I think the connections are in either the driver run bay or the passenger side battery bay.

How do I determine which?  Should I submit pics of both bays? Procedurally, I'm sure I need to shut off bypass switches or disconnect cables, but I'm not sure of which ones, in what order, etc.

Thanks in advance for any advice or pointers. 

Steve

Steve,

On our 2005 Exec (admittedly different), the 12VDC starting feed to the generator is located at the front run bay, outside under the driver’s position. The wires are connected to the outside terminals of the high-current cables, on the leading side of the bay enclosure. It’s relatively easy to identify the generator cables by following the cable run. 

I ended up with a more complicated solution involving a standalone battery for the generator, but that’s a different issue. 

I agree with the comment that accessing your wiring schematics for the front and rear run bays would help guide your search. 

[Tom Cherry]

Steve,

Many folks do this.  Some of the newer Models come with the Genny being started from the Chassis.  If you do that, and MY OPINION, you will be prone to more issues.  If your Chassis is dead....then you are totally INCAPACITATED.  

The other issue....the wiring for that may NOT be as simple as you might thing.  It all depends on how the battery busses (the distribution points) from each bank are made.  Could be as SIMPLE as moving one cable.  BUT, also, the folks with the newer models and higher food chain, often report a "Phantom" Genny will NOT start. We have many members whose Dynasties and above came with Cranking Battery starting and they add a supplemental battery...NOT A SMALL JOB.

NOW, to keep it simple.  Carry a set of Jumper Cables in the MH or in your TOAD.  If you JUMP or connect the HOUSE to the Chassis, you have the ability to crank the Genny.  The ONLY CAVEAT....Turn OFF each or BOTH Disconnect switches....THEN hook up the Jumpers.  Folks and I have, often do that when we get a fluke in our charging system and run down one or the other.  That is my advice....but your MH and others may (will) feel strongly about doing the conversion.

From a PRACTICAL standpoint.  YOUR Boost Switch or the ability to combine the banks is HOUSE POWERED.  SO, if you don't have ENOUGH Juice to CRANK the GENNY....then odds are, there will NOT be enough voltage or current to "engage" the Big Boy....The Big Boy has two functions.  BIRD charging....and then to let you (read the manual) put a surface charge on the CHASSIS and then be able to CRANK the Engine.  

ALSO, be aware that your BIRD must be 100% functional....otherwise if you rewire and your Chassis runs down...you have NO WAY to start the Genny....other than the KISS of Jumpering.

SO, your call...but a simple 5 minute drill to jumper the HOUSE and CHASSIS accomplishes what you want....and also gives you the OEM benefit of being able to START the MH....If you leave the MH in storage or spend a long time camping and your CHASSIS goes DOWN....a COMMON occurrence...then you have excerbated the situation...and have to start using a CAR.  That is more dangerous to the electronics in the MH....often folks have done significant damage.

THAT is why I am an advocate of "KISS"  Turn OFF both Disconnects.  Attach the Jumper Cables.  Turn the batteries back on.  Crank the Genny or conversely....crank my ENGINE....then let the run a while for either the engine (alternator) or Genny (House) to recharge.  SHUT OFF BOTH ENGINES.  TURN OFF the battery switches.  Remove the cables....turn back on and DRIVE or go on.

 

[Steve P]

I'm all for keeping it simple... I need to look harder at the wiring of the 2 battery banks.

 I suppose if I identify the positive and negative ends of each chain of batteries, I will know which end is plus and which end is ground for each bank, and I can connect house plus to chassis plus and house ground to chassis ground.  Is that correct? 

[96 EVO]

I have no regrets switching my gen starting power to the chassis bank!

IMO, should have left the factory that way!

[Tom Cherry]

43 minutes ago, Steve P said:

I'm all for keeping it simple... I need to look harder at the wiring of the 2 battery banks.

 I suppose if I identify the positive and negative ends of each chain of batteries, I will know which end is plus and which end is ground for each bank, and I can connect house plus to chassis plus and house ground to chassis ground.  Is that correct? 

YES....that will be evident when you pull open or go into the battery compartment.  NOW...remember....no matter if you have to use a vehicle to jump off the engine or the genny (house bank), you ALWAYS need to turn OFF BOTH BATTERY SWITCHES....THEN ATTACH the Starting Battery (Car or whatever) OR Do the INTERNAL JUMPERING.,....That is critical...

YES....POSITIVE TO POSITIVE (from Each Bank) to Negative.  You have FOUR batteries on the HOUSE.... use the Front or REAR ones....

Since this seems to be a little unfamiliar....I took a page out of your manual.  Still suggest, that as you progress or want to understand, read BOTH the electrical session.

As the SAY...One Picture....10,000 key strokes....  OK...look at the marked up file.  The SOLID Black Lines are the MAIN JUMPERS between the Batteries.  So, any of the ones I marked are OK.  NOW, for your continued education.  See the smaller, grayed out ones between each set of HOUSE BATTERIES.  These commonly are KNOWN as the INTERNAL or the HOUSE Connectors...my terminology.  They connect one 6 VDC to another....thus the TWO, in SERIES are 12 VDC.  BUT the large Black Jumpers, that connect the Chassis to each other and the two "sets of 6 VDC" are the Cable or Jumpers that put the batteries or "set" in parallel.  That means you get BOTH batteries or "sets" in parallel.  The CURRENT from each is added.  SO, if you have 225 Amp Hours in a 6 VDC battery....that is the SAME for the two batteries in series or with the small gray jumpers.  BUT, when you put the TWO sets in Parallel, you have 450 Amp Hours of current.  Many folks don't know that....as they never had to "work with it", so if you knew that....just repeating....but it NOT, then helping you to learn.

Ben responded...as expected. and he is happy with his decision.  He is very experienced and knows how the entire system works and did his own rewiring.  I have the same MH and there is a great print...as well as easy to see cables....  BUT, for curiosity's sake, I went through your prints.  TOTALLY DIFFERENT...which happens.  You have ever piece of pipe and fitting detailed...  BUT there is no where, that I saw, the High Current Print showing the large fuses (presumably) that connect the Generator to the House Buss....  Also went through the Manual.  NO PICTURES or High Current Fuses listed for the rear.....  SO...I'm sure we have a LOT of experienced folks that could easily understand and trace circuits and move things around...  But, I can't find any prints to even offer, as you learn MORE, how you would do it.

That's my take....

JUMPERING HOUSE AND CHASSIS BATTERY DIAGRAM - 2009 KNIGHT...AND OTHERS.pdf

[Tom Cherry]

@Steve P

After ALL my scrolling around and browsing in your manual...and then realizing that you might not be aware of a serious safety, as in FIRE and HUMAN LIFE PROTECTION, I am using this comment to alert you .  There are literally 10 or more Topics on it.

BUT, when we have a new to them owner of a Monaco MH, we, the STAFF, always POST THIS...

Here is a page from your Owner's Manual. Page 163.  IF you STILL HAVE this Automatic Transfer Switch....the IOTA "50R", then if you are NOT AWARE....it is a safety issue, was recalled....but your MH, since it was made by Monaco, was EXEMPTED from the MANDATORY replacement that Navistar had to do or VOLUNTEERED to DO.

Please check this out.  Go to the bay with the ATS and look at the one you have.  IF IT IS THE IOTA 50R, be aware.  It can catch fire.  It can shut down the MH. It CAN cause issues....we have not, to the best of my knowledge, had a REPORT HERE of a real fire...but numerous....NO EXAGGERATION reports and pictures of the internal charring and getting HOT and MELTING issues.

If you have that, the advice is to not leave any power on the MH and to have it REPLACED by a qualified Electrician or Tech. It, TECHNICALLY, is NOT a RV or Motorhome EXPERIENCED person.  Any well qualified HOME or Commercial or Industrial Electrician or contractor can do it.  However, many BALK as "we don't KNOW".

There are MANY brands of ATS that folks have used.  The most stocked by the large RV repair shops and the most commonly used is the ESCO LPT50BRD.  There are a LOT of knowledgeable shops that prefer and use other brands.  IF you want to read up, then put IOTA in the Search Box and select TOPICS.  

Be prepared to sit down and READ and make notes.  There are members that have been very satisfied with OTHER ATS....but, I can NOT name or recall one specific one that gets 10% of the "Votes" compared to the ESCO.  I chose that.  I got the recommendation from the EX General Manager of the former Large Monaco Repair center in Florida.  Monaco used a "bulletproof" ATS many years ago....and all our oldtimers swore by it.  BUT, it was an AC powered circuit board and it HUMS....built tough.  When I got the recommendation, as a moderator of the original site, I did extensive calling as we were advising members.  I called ESCO.  They told me....use the LPT50BRD....instead of the "make a noise and hums" model that they still make.

SO, I have too much "personal capital" invested...and only offer what I know is fact.... and we have, as I said, a lot of other brands in use....some, however, with regrets....but if you want to read the posts....it is ALL in there.... Some 11 pages and over 271 posts... The link below will take you to the search results....sit down...get a drink....read and then decide....

THIS IS IMPORTANT....

 

https://www.monacoers.org/search/?q=IOTA&quick=1

 

 

IOTA ITS-50R ATS - RECALLED.pdf

[Steve P]

1 hour ago, Tom Cherry said:

YES....that will be evident when you pull open or go into the battery compartment.  NOW...remember....no matter if you have to use a vehicle to jump off the engine or the genny (house bank), you ALWAYS need to turn OFF BOTH BATTERY SWITCHES....THEN ATTACH the Starting Battery (Car or whatever) OR Do the INTERNAL JUMPERING.,....That is critical...

YES....POSITIVE TO POSITIVE (from Each Bank) to Negative.  You have FOUR batteries on the HOUSE.... use the Front or REAR ones....

Since this seems to be a little unfamiliar....I took a page out of your manual.  Still suggest, that as you progress or want to understand, read BOTH the electrical session.

As the SAY...One Picture....10,000 key strokes....  OK...look at the marked up file.  The SOLID Black Lines are the MAIN JUMPERS between the Batteries.  So, any of the ones I marked are OK.  NOW, for your continued education.  See the smaller, grayed out ones between each set of HOUSE BATTERIES.  These commonly are KNOWN as the INTERNAL or the HOUSE Connectors...my terminology.  They connect one 6 VDC to another....thus the TWO, in SERIES are 12 VDC.  BUT the large Black Jumpers, that connect the Chassis to each other and the two "sets of 6 VDC" are the Cable or Jumpers that put the batteries or "set" in parallel.  That means you get BOTH batteries or "sets" in parallel.  The CURRENT from each is added.  SO, if you have 225 Amp Hours in a 6 VDC battery....that is the SAME for the two batteries in series or with the small gray jumpers.  BUT, when you put the TWO sets in Parallel, you have 450 Amp Hours of current.  Many folks don't know that....as they never had to "work with it", so if you knew that....just repeating....but it NOT, then helping you to learn.

Ben responded...as expected. and he is happy with his decision.  He is very experienced and knows how the entire system works and did his own rewiring.  I have the same MH and there is a great print...as well as easy to see cables....  BUT, for curiosity's sake, I went through your prints.  TOTALLY DIFFERENT...which happens.  You have ever piece of pipe and fitting detailed...  BUT there is no where, that I saw, the High Current Print showing the large fuses (presumably) that connect the Generator to the House Buss....  Also went through the Manual.  NO PICTURES or High Current Fuses listed for the rear.....  SO...I'm sure we have a LOT of experienced folks that could easily understand and trace circuits and move things around...  But, I can't find any prints to even offer, as you learn MORE, how you would do it.

That's my take....

JUMPERING HOUSE AND CHASSIS BATTERY DIAGRAM - 2009 KNIGHT...AND OTHERS.pdf 322.53 kB · 1 download

Thanks for the diagram and the explanation.  This will make it very easy to no what to do to jump if I have to.  

Unlike you, i do not have any wiring diagrams other than those that Myron Truex sent me in a very helpful OneDrive set that starts with 2005 and goes up from there.  I am wading through those diagrams to solve an instrument cluster lighting problem on the analog gages, even though they are for a 2009 model.

[Tom Cherry]

14 minutes ago, Steve P said:

Thanks for the diagram and the explanation.  This will make it very easy to no what to do to jump if I have to.  

Unlike you, i do not have any wiring diagrams other than those that Myron Truex sent me in a very helpful OneDrive set that starts with 2005 and goes up from there.  I am wading through those diagrams to solve an instrument cluster lighting problem on the analog gages, even though they are for a 2009 model.

We, the staff, always like to help and educate....  LOL.  Seriously, the drawings are in our files.  I used the search box.  Put in Wiring.  Then clicked on Everywhere.  3 pages.... this was on the first page.  This is what I went through this morning.

Download it. You have them....  They are "different" as in Monaco had teams of "engineers" and a particular model or chassis might have had their "own" system of drawings.  I have seen or been into a LOT, a WHOLE LOT as I keep them on my hard drive to save time...  The Knight was the first one that EVER had all the plumbing and a bill of materials showing every piece of pipe and joint and fitting.

It is a LITTLE shy on wiring...but there are a LOT of useful things as the schematics for your entertainment system.

NOW...you have NOT responded and confirmed whether you have the IOTA.  We DO WORRY about folks....so call us Mother Hens...  Thanks...

 

 

[Steve P]

No IOTA.  See pics.  Thanks for the very valid concern!  Light Power Systems LPT50MRD.

Is the 2009 Knight likely to be mostly like my 2008 (built June 2007)?

[Tom Cherry]

26 minutes ago, Steve P said:

No IOTA.  See pics.  Thanks for the very valid concern!  Light Power Systems LPT50MRD.

Is the 2009 Knight likely to be mostly like my 2008 (built June 2007)?

Great....I'll wager that it is spelled LYGHT.  Lyght sold out to ESCO and they just started making.  They LOVED IT...so you have one of the originals...unless it has an ESCO sticker somewhere.  GOOD NEWS...we DO worry about folks...

You MIGHT be able to call REV and get a build date from the VIN.  Supposedly there is a "code" so you can google RV VIN Manufacturing Date and see...

My 09 was an August 2008 build.  Monaco would sometimes carry over a year...but NEVER more...so it is, my guess, a 2008 build.  The stuff that was on the line in mid January 2009 got stranded...and all were given a 2010 MY....THAT i know for a fact.

[dandick66]

The generator in my 2012 Diplomat was wired to the house batteries, but I changed it to the the chassis batteries.  I noticed the generator was hard to start from the house batteries unless I was connected to shore power or the engine was running.  I did not see any improvement in starting when I changed it to the chassis batteries.  My next project is to install an auxiliary starting battery and isolator for the generator.

The main reason I wanted to change it to the chassis batteries is because of the Aquahot.  If the Aquahot voltage drops below 12 volts it cuts off and has to be manually reset when the voltage is above 12 volts.  Of course this happened at 0300.  The AGS was set at 11.9 (default) and wouldn’t start the generator.  That’s when I decided to change it to the chassis batteries. I changed the AGS to 12.1, but the generator struggles to start from the chassis batteries.  The batteries are good as I have no problems starting the engine.  I’ve checked cables and everything is good, clean and tight.  Maybe the cable run is too long.  

[96 EVO]

20 hours ago, dandick66 said:

  The batteries are good as I have no problems starting the engine.  I’ve checked cables and everything is good, clean and tight.  Maybe the cable run is too long.  

Yeah, I think they should have used larger dia cables, given the length!

There's no way that little 3cyl diesel should struggle to turn over with 1900CCA of battery power, when the ISL doesn't!

[Tom Cherry]

20 minutes ago, 96 EVO said:

Yeah, I think they should have used larger dia cables, given the length!

There's no way that little 3cyl diesel should struggle to turn over with 1900CCA of battery power, when the ISL doesn't!

Ben,

I don't have an issue....but I have the 8KW.  BUT, you know my curiosity....as well as yours.  I pulled the 10 KW Onan manual.  It says....  one of them 475 CCA Battries.....sarcasm.  NO SPECS.... OK....more googling.  Here is the thread that came up...

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29965839/print/true.cfm

Cut and PASTE of at least SOMEONE's testing....how GOOD....NARY A CLUE...but it does have data and seems to be logical.

As shown in the picture below, my generator (Onan 10 KW QuietDeisel) has a dedicated battery that is only used to start the generator.

• 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.

As you may have guessed, I am a proponent of using a dedicated battery for the generator. As per a previous post, I found that even when I cleaned all my terminals from the house batteries to the generator, the generator just did not start reliably. After installing the dedicated battery, I have never had a problem. IMO...

1. Due to the high current draw, 30 - 40 feet of 4/0 cable just has too much voltage loss.
2. The house batteries are deep cycle batteries. Therefore, they are not designed to supply the 200 Amps necessary without pulling down the battery voltage significantly.
3. When you really need to start the generator (i.e. In the morning when you house batteries are at 50% - 12.0V --or-- during cold weather) that is also the time when you have the lowest voltage available and cannot handle further voltage drop as the starter cranks.

NOW....BACK TO OUR RIGS....

My print for my 2009 Camelot shows only ONE High Current print....NOT one for an 8.0 or a 10.0.  SO, I assume, if yours is, as I think, like mine.....there is the skinny.

The Generator direct cable from the REAR to the Front is fed by a 125 Amp ANL Bussmann Ignition Proof fuse.  I VERIFIED THAT a long time ago and have the spare.  BUT, LO and BEHOLD....the cable size is only 1/0.  Check your print....is that what it says or what you have?.  OK...on the the SOUTHWIRE calculator... OPPS...it considers it as AC and continuous...

THEN, I pulled this chart.  

https://www.directwire.com/resources/welding-cable-ampacity-chart/

OK....this is my logic...and sometimes hard to follow.... so I may be wrong.  IF you had 50 Ft of 1/0 cable.....then that would get you up to 350 Amp.  Only takes 207, per the guy that measured it.  SHOULD be OK.  

NOW...  what if you had 50 Ft of 2/0.  BINGO....you go to 450 or a 100 Amp increase.  MY DUMB IDEA....and I could do it on mine....  If I wanted to Kick UP the DC Cranking amps....  I would do the following.  Run a NEW, short, maybe 10 Ft cable from the Chassis Post on the PCB.  That is a 2/0 feed.  There is ROOM to attach it....I have done something similar....  Then add in a 2/0 Negative cable...or replace the one that is there...or drill a hole and tap the Chassis and such.  That would then give you 200 Amps of power....on the FUSED side.  BUT, we know, from experience, that a short burst of a high current spike will not take out a heavy fuse.  I have never popped my 8.0 KW fuse of 125.  There are TWO PCB (in the FRB) studs.  BOTH ARE 2/0.  BOTH have a 200 Amp Battery Buss fuse....one for the House and one for the Chassis.  You NEVER need, anywhere, that high a current for the Chassis.  Maybe at PEAK...40 or so.  Same for the House.  I have, as you do, the Lippert Hydraulic pump.  It ONLY pulls or supposed to pull 65 Amps....and your's is protected at 80....mine is a goof and was 150 and I replaced it.

SO, either use the HOUSE or the CHASSIS....  In fact, like I did, you COULD use a selector switch... Blue Seas, which is rated at 300 A and have BOTH them suckers pumping out amps...and be fused....at 400 Amps...as you have a DUAL feed (200 plus 200).  Run a piece of 4/0 rather than 2/0.  THAT looks like a way to always have the Onan cranking.  Easier that running a new cable all the way....and there is a LIMIT on the BUSS.  Technically, you would have to run a 3/0 or 4/0 and fuse it much higher...  Replacing the Ground or Chassis Cable is easy.

I don't argue that there may be an issue.  I also know a lot of 42 Ft (10 KW) Camelot owners....one full timed for several year and followed the INDY circuit and drove all over the country and stayed in mostly NO POWER fields.  He never had an issue cranking.  The folks with the Dynasty and above that have cranking issues, generally, are a small minority....and it has been jawboned (clicked?) to death here.  The ones that had the issue....either lived with it or added a battery.  

I don't have a better solution or explanation that that.  BUT, for the folks with the 8KW, there has NEVER, to my knowledge, been a post about Too Small a Cable.  it is MOSTLY a "Bad Ground" connection from the House to the Stud behind the box or a rusty Ground connection up front.  I had the former...  Would NOT crank.  Figured it out....and didn't mess with it till I got home and NEVER, once the connection was GOOD...as in the tray was SHUT and the GROUND (resistance) was ZERO...it would crank.  Cleaned the Ground Stud.  Never a problem in over 8 years and 40K and at least a year's worth of full time camping and running the Genny for HVAC as the GK and DW got HOT.  Genny NEVER missed or would not start.

The 10KW is bigger...but Monaco only sized ONE circuit.

What do you think?

[96 EVO]

I think it may be worth looking into!

I had a slow crank on my gen just this morning, in close to freezing weather. My two 950CCA chassis batteries are only a year old!

I never knew they ran a heavier gauge chassis bank cable to the FRB!

Thanks!

[Tom Cherry]

43 minutes ago, 96 EVO said:

I think it may be worth looking into!

I had a slow crank on my gen just this morning, in close to freezing weather. My two 950CCA chassis batteries are only a year old!

I never knew they ran a heavier gauge chassis bank cable to the FRB!

Thanks!

Trust me...  LOL....when you fought voltage drops and had a Hydraulic failure and did a LOT of troubleshooting...you learn a LOT.  Them TWO studs up front, assuming you have TWO 200 AMP fuses in the back...with one on the House and one on the Chassis go to the FRONT....

If you did NOT change the cable from the back to the GENNY...then the issue is in the cable.  SO, popping in a "jumper" up front and running to the Genny and use either (or BOTH...a $30 Blue Seas Selector switch) should do the trick.

I have NOT have to use my Selector switch in the TWO BATTERY or BOTH position...and when I change out the House Switch, which has a wee drop....the House will be GREAT for the hydraulic. Right now, the 200 Amp line to the Chassis Stud powers my Hydraulics...and RUNS GREAT

Even sight challenged swine find a morsel....if they hunt long enough.  LOL...

[96 EVO]

No, I didn't change the long gen pos cable when I made the switch to chassis. Just moved my ANL fuse from house buss to chassis buss, with a portable ANL fuse holder.

[Tom Cherry]

2 hours ago, 96 EVO said:

No, I didn't change the long gen pos cable when I made the switch to chassis. Just moved my ANL fuse from house buss to chassis buss, with a portable ANL fuse holder.

Then, in my simpleton's logic.  You added a REAL starting battery...with a higher peak CCA.  The cabling is the "bottleneck".  YES, adding an inline 200 Amp ANL would work and is safe.  BUT, I think a short run cable from the FRN using either the House or Chassis and beefing up the ground would maybe have made the House OK.  The house does NOT have the deep reserve or BURST for starting.

Monaco did strange things.  On the Dynasty...they start from the Chassis.  IT MAY be that Monaco never, GOD FORBID, actually thought THROUGH adding the large 240 VAC genny to the Camelots....as they need the extra current for the 3rd AC.  1/0 is, my opinion, a bit SMALL.  SO, using the existing Chassis 200 Amp stud/fuse and putting a 4 or even a 2/0 cable from the Chassis stud would give you more "CCA" for those times when you need it...

OK....YOU HOOKED ME.  The 2008 Dynasty (and all upper ends) have a 4/0 cable from the Starting or Chassis Battery to two studs in the FRB.  Then the Genny (10 or 12) is powered or started by a 2/0 Run from that stud to the Genny.  I ain't no genius....but, I DO wonder if all the complaints about the problems with the "BIG BOYS" starting would be solved by running a 4/0 to the Genny.  That seems to be the weak link.  NOW, having said that and been down this path with folks that have the problem and hearing the "Gee, MINE NEVER HAS AN ISSUE", that may be too simplistic.

BUT, in your case...I think a new 2/0 or maybe a 3/0 just to NOT have that additional voltage drop from the Chassis Stud up front and an upgrade of the Ground Cable might solve the issue.  BUT...how bad it is and how much it bothers you...  Who knows.  BUT, swapping the cable to a set of batteries with a little more KICK....think the HARE....vs TURTLE probably helped...but the undersized cable is probably more of a bottleneck.

Again, Ben, that is my thoughts from looking at both schematics and then trying to apply some common sense.  In reality... putting a Blue Seas switch up there....with a 2/0 feed to BOTH of the 200 Amp services...and THEN running a 2 or 3?0 to the Genny with a 2 or 3/0 ground upgrade...and then setting that for BOTH.  That ought to spin that mill... Like NOBODIES BUSINESS.  You would have a 400 Amp potential.  

NOW, the DOWNSIDE...you JUST eliminated the BIG BOY.  Your batteries are CONNECTED...or Bonded....  NOT forever...but always when you leave the switch in the BOTH position.  Frank and I kicked that around when I added in the switch.  He commented that 300 Amp switch was about as good as the Big Boy....and YES, the 2/0 was bit WEAK...but since the Big Boy was only 200 A, what was the purpose of running the 4/0 cables between the two busses and through the 200 amp (Continous) Big Boy.

I do NOT leave my switch in the BOTH position... and like Frank, I bond the two banks when in long term storage.  In effect...I could do the same with the up front switch....and just, as I did, disconnect one of the control wires to the Big Boy.

Lots of muddling...and some of the Monaco engineers suffered from "Muddled" thinking...  LOL

[96 EVO]

Yeah, I'm going to look into this mod further, in the spring.

I think that long small dia pos cable from the rear run bay has to be the bottle neck!

[dandick66]

I’m out of town this week, but will check my wiring when I get back home.  I’m pretty sure my generator is connected by a long 2/0 cable from the RRB.  I’m going to check the FRB and see if I have two 4/0 cables coming from the RRB chassis and house batteries.  If so, I’ll make a 4/0 cable to run from the FRB stud to the generator.  I’m curious about the ground, though.  Wouldn’t be ok to just leave the current - no pun intended - ground cable?  I know on car batteries the ground cable is much smaller gauge than the positive.  

[96 EVO]

Give us an update if you do it!

Your 2012 Dip has the 10KW Onan?

[dandick66]

1 hour ago, 96 EVO said:

Give us an update if you do it!

Your 2012 Dip has the 10KW Onan?

Yes, I have the 10kw Onan. 

[96 EVO]

5 hours ago, dandick66 said:

   Wouldn’t be ok to just leave the current - no pun intended - ground cable?  I know on car batteries the ground cable is much smaller gauge than the positive.  

It's a fairly short cable, then uses the frame to return to battery ground.

I would 'think' the original would be fine, but I'm no electrical wizard!

[dandick66]

On 10/31/2023 at 10:41 AM, 96 EVO said:

Give us an update if you do it!

Your 2012 Dip has the 10KW Onan?

Well, I finally checked out the cabling.  I have a 2/0 that runs from the RRB directly to the generator.  There was is another 2/0 from the RRB chassis battery to the FRB stud and a 2 gauge (Not 2/0) from the house batteries to the FRB. So, no 4/0 running from the rear to the front.

I looked at Walmart today and I can get a group 24 battery for $70.  I think I’ll get one and a battery box and mount it near the generator.  I need to figure out how to connect a combiner/isolator.