Charging: House, chassis or both?

[Newcsn]

Coach batteries dead this AM when I went to start it. Of course, it's sat for a couple months w/o being plugged in & it's been pretty cold around here. Attempted battery boost on dash & still nothing. Apparently all have lost their charge.

When plugged in, do both house & chassis batteries charge or just house?

Haven't had this happen previously - always left it plugged in to 15A service. Just want to know how the charger works.

Thanks!

[vito.a]

Both charge.  Check your Intellitec Big Boy solenoid in the rear run bay.  They are notorious for carbon buildup on the interior contacts.  

[Newcsn]

 

10 minutes ago, vito.a said:

Both charge.  Check your Intellitec Big Boy solenoid in the rear run bay.  They are notorious for carbon buildup on the interior contacts.  

Vito.a - Thanks for the feedback! Is the Big Boy solenoid something I can remove, disassemble & clean? Thanks

[Newcsn]

Vito.a - Disregard my earlier question. I found your post on IRV2 with the attachment "Big Boy Relay rebuild instructions".

Thanks again!

Big Boy Relay rebuild instructions.pdf

[Tom Cherry]

1 hour ago, Newcsn said:

 

Vito.a - Thanks for the feedback! Is the Big Boy solenoid something I can remove, disassemble & clean? Thanks

Yes,

READ THIS…Vito has you on the right track.  Here is a trouble shooting and advice guide…..

many do it.  Some buy a new one and then clean and rebuild and carry as a spare.  Go to the SEARCH bar in the upper right.  Put in Big Boy.  There is a drop down and the default is EVERYWHERE.  Click on that and choose FILES.  Frank McElroy has a HOW TO on cleaning and rebuilding.  There are no parts to order and all you need is a little dielectric (memory) grease….or Bulb Grease.  He also comments on how to get the “top” off.

There will also be a file on the “Intellitec Service Manual”.  I had to replace mine in 2021…..after 12 years and it had always had 30 A power in storage….plus over 200 “nights” out and 65K or so.  I decided to purchase a new one as it killed my older Chassis batteries.  

Now, look on pages 284 and 285 in your manual.  That provides a picture of where the Big Boy is located.  The REAL Question….is the control board for,the Big Boy working.   Also is the Boost switch working.  Assuming your house batteries are charged, then you need to test the Big Boy.

The first thing I would do, with the HOUSE, presumably, charged.  Unplug your shore.  You might hear a CLUNK from the Big Boy.  NOW Measure the voltage on each side of the Big Boy. Put your common to a GOOD chassis ground and the “red” to each large terminal.  Repeat and measure the voltage on the Chassis and House.  Now compare to the Big Boy.  You will see, probably, the house is higher and the chassis is lower….then you know which terminal is HOUSE and which is CHASSIS.  

If you plug in the inverter, you MIGHT hear a clunk.  But the 15 amps might be too low to engage it.  This is the next step…

I would recommend recharging the chassis first as the Big Boy and the control is designed to keep from running down both sets.  The way I did it was to use a single jumper between the House and Chassis positive and jump start the engine.  Let it run a while.  That puts a surface charge back on the Chassis.  I am not sure which battery starts your Genny.  Drive it as that will definitely charge it,  or let it idle a while,  15 amps is a bit low for effective charging.  You also need to exercise your Genny and Polish the brushes.  Start the Genny.  That will give you full amperage to start the Magnum charging.  You can also now shut off the engine.

BUT FIRST….REMOVE THE JUMPER CABLE….let it idle and do some voltage measurements.  The 200 amp alternator is pumping out current.  If you go back to the Big Boy, it should be closed and getting warm and “humming”.  The alternator voltage will be around 13.9-14.0 voltages or in that ballpark.  You will see or measure that on the CHASSIS side….so remeasure from ground to Chassis stud.  Should be the same.  Now measure the House side.  It the big boy is closed and working, then the voltage should be the same.  If the House side is LOW or the same 12.6/7, then the big boy either has a bad contact or a bad coil or the control board is not working.  

NOW, you need an assistant.  Push in the Battery Boost switch and you should hear (with your hand on the can….you can FEEL the clunk).  When it is engaged, then if you measure the House and it is still low….then you have a contact issue.

A redundant test is to shut off the engine.  Then have an assistant push the boost.  There should be a loud clunk.  Coil works at full voltage.  The voltage on either side of the terminal will be within 0.03-05….that is HUNDREDTH….not Tenths.  If higher you have a bad or corroded contacts.

NOW start the Generator.  That is giving you FULL charging current.  Within a minute or so, you should (hear) know the big boy is closed.  If you stay back there and have the assistant start the Genny, keep your hand on the can….

you KNOW it worked with the boost,  the Chassis is DOWN, but should have enough surface charge to start or almost start the engine.  So, the control board should have closed the coil contacts.

There are topics here on measuring the DYNASTY (and UP) coil voltages.  This is different from folks like me with a Camelot that have the Intellitec system.  

When  you did your search, Frank has a file on how he repairs the Dynasty board….

Thats the basics and how to trouble shoot.  

DO NOT BE SURPRISED if all is well.  I lost power and the Big Boy did not reengage and my Chassis was down.  But when you cycle it now, it might work.  If the coil and the board are working OK, the CLEAN IT….as it will probably fail on you again.  It is 16 years old. Or put in a new one and then clean thie old and keep for a spare.

BUT, you have to make sure that the control board is working and it kicks on with Boost as well as when charging….from Genny or Engine…

[Newcsn]

Tom Cherry - Thanks so much for the feedback!

[Tom Cherry]

51 minutes ago, Newcsn said:

Tom Cherry - Thanks so much for the feedback!

Most Welcome.  I regret that I am NOT well versed in how to check the Control Leads (small wires) on the Big Boy.  There is some crazy way that they are wired and I don't know what the readings should be.  I THINK that if you measure the control voltage when the Big Boy is "Engaged" and you are in the BIRD (Bi Directional) charging mode....the NORMAL state, that you should read maybe 3 - 5 VDC (don't worry about polarity....that is the mystery) across the two terminals....one is DOWN UNDER, I think, from the picture.  There has to LOW voltage to hold it ON, CONTINUOUSLY.....  When it first comes on, the control board sends a full 12 VDC.  That is also the same full 12 VDC that comes when you hold on the Boost Switch.  That is why your manual warns you NOT to leave it in (the switch) or "jimmy" it.  A full 12 VDC for more than say a few minutes will burn up the coil. BUT, the reduced voltage will not hurt the coil.

Good Luck....keep us informed.

[Newcsn]

Thanks again for all the feedback - truly appreciated!

I haven't had the time to execute the full diagnostic plan as suggested. However, I did have the coach plugged in for about 4 hours & then attempted to start it. It would not start off the chassis batteries - however - it did start when I used Battery Boost. Therefore, my assumption is that the Big Boy is working correctly - at least in the Boost mode.

We also drove it for about 60 miles & it appears the chassis batteries are now charged as it restarts w/o Boost

Thoughts?

[Tom Cherry]

1 hour ago, Newcsn said:

Thanks again for all the feedback - truly appreciated!

I haven't had the time to execute the full diagnostic plan as suggested. However, I did have the coach plugged in for about 4 hours & then attempted to start it. It would not start off the chassis batteries - however - it did start when I used Battery Boost. Therefore, my assumption is that the Big Boy is working correctly - at least in the Boost mode.

We also drove it for about 60 miles & it appears the chassis batteries are now charged as it restarts w/o Boost

Thoughts?

You need to determine if the big boy is engaged.  Simplistic.  If you have your 15 amp shore, is the big boy warm or almost hot and humming?  Kill the shore.  You should hear or feel the big boy go clunk and open up.  Wait a few minutes.  It should start to cool off.  Start the Genny from the front or from the dash and quickly get back to the open RRB.  IT takes a minute or so for the ATS to close and full voltage to the charger.  Put your hand on the big boy.  Eventually it should close and go clunk.  If that happens, then the control board is working.

but you still don’t know about the contacts.  Only way is to measure each side.  Or put a VOM on each terminal (studs).  If you read more than 0.03 - 0.05 (hundredths), you have pitted contacts.

it is easier to know what you are dealing with and what could be the problem than shotgunning it.  Too many times folks post….I “THOUGHT” that I needed to replace this based on what I read or what somebody posted.  NOPE….still have the issue.

New parts not needed will not fix something that is broken or bad somewhere else.

ODDS ARE….you need to clean or replace the Big Boy.  But until you determine it in coming on and the control board is working, it is a crap shoot.

folks spend a lot of time chasing ghosts because the don’t understand how something works or how to troubleshoot and eliminate issues.  That is what we moderators want to eliminate. Proper troubleshooting is more efficient and saves repair bills and needless new part purchases.

That’s why I went into detail.

[Newcsn]

Thank you Tom! Totally get the need for thoroughly running the diagnostics & not being a parts swapper (In my previous life I was a Master Tech for GM & worked with a number of folks that were parts changers - at best)!

Will continue the diagnostics as time & weather permits!

Truly appreciate you taking the time to moderate this site & provide detailed feedback!

Thanks again!

[Frank McElroy]

On 11/29/2022 at 10:50 AM, Newcsn said:

Coach batteries dead this AM when I went to start it. Of course, it's sat for a couple months w/o being plugged in & it's been pretty cold around here. Attempted battery boost on dash & still nothing. Apparently all have lost their charge.

When plugged in, do both house & chassis batteries charge or just house?

Haven't had this happen previously - always left it plugged in to 15A service. Just want to know how the charger works.

Thanks!

If you plugged into shore power and only the house battery bank charged and once the house batteries were charged, if the chassis battery bank did not also charge, then yes, likely your big boy needs to be cleaned.

However, you mentioned that the coach sat for a couple months w/o being plugged in.  (I assume you didn't have solar to keep the battery banks charged.)

Even if you turned off the battery switches, there would still be a parasitic load.  On my Dynasty, that load is 5 amps.  If I turn off the Magnum inverter at the inverter itself (not at the remote), and turn off the battery cutoff switches (my inverter doesn't pass through the battery cutoff switch), the parasitic load drops to 1 amp.  So, on my coach, that's a parasitic load of 24 amp hours a day and in about 3 weeks, my house battery bank of 900 amp hours would be below 50% SOC just from the parasitic load.  After 2 months just from the parasitic load alone, the batteries would be flat dead.

My solution is if I have to store the coach more then a week not plugged in is to physically disconnect the batteries (I don't have solar).  Since my battery banks are balanced (connected such that the positive and negative cables from the coach are not on the same battery), all I do is remove one end of each short battery cable to stop electrical flow through the battery bank.

[MyronTruex]

I hope this does not confuse anyone.

In many "big boy" setups, the solenoid is first engaged with the full battery voltage. That is after the appropriate "delay". 

You can get tricked into thinking the control voltage is not coming from the bird controller if not patient. This "delay" works two ways. The delay at first is to help prevent a huge load of a run-down bank of batteries from causing the relay to cycle on and off. So the control device waits till things have stabilized a bit before combining battery banks. Once combined, the voltage can drop below the threshold but won't release the "big boy" for a couple of minutes. At that time the surface charge may be enough to make the controller happy. In any case, It may cycle a few times if a bank is severely depleted.

Now I first mentioned the "big boy" is activated by the full voltage of the bank that is being charged, but after that, it goes into a pulsating DC voltage. This pulsing measured by a voltmeter comes across as a low voltage. Five or so volts. This pulsing is sometimes reported by hearing a humming in the area around it and is annoying to some folks. 

The Boost switch applies full voltage to the control wire on the Big Boy, thus bypassing any "bird" control circuit. I know, not exactly as it may pass through the bird control device. In any case, using the Boost switch to help diagnose a bad Big Boy makes things a bit easier/quicker. Not time waiting for the "delay" part of the controller. 

Seeing different voltages on the large terminals is an immediate issue. But nearly charged, or charged batteries can fool you into thinking things are fine. Without a load passing through the heavy contacts of the relay, there is no voltage drop. Which makes you think things are fine. 

I have recommended rebuilding the true large “Big Boy” about every three years. In my case, the relay “Trombetta”, about the size of a fist, is not worth the effort to rebuild unless you just want to. Replacing it with a silver contact one is not expensive in our world.

It was extremely painful learning my system. There was no information available at the time Monaco was going bankrupt. Fortunately, I have years of experience working through systems in vehicles when there is no documentation. The “Trombetta”, failed less than two years from now. I believe it was caused by the heating and cooling of it, thus drawing moisture into it. The contacts were absolutely green when I took it apart. The factory install had the solenoid basically upside down so no moisture could exit. It just accumulated over time. I have replaced many solenoids that have been mounted upside down over the years. It is a problem under the hood of a vehicle where water can splash onto them.

Here is some information I wrote some time back. It applies mostly to those of us that have the "Trombetta" that is often in the battery compartment versus the huge "big boy" mounted elsewhere. 

----------------------------------------------------------------------------------------------

First let’s clear up the "Big Boy" question. It is like calling all tissues Kleenex.

To be specific there are several variations of the "Big Boy" solenoid. The solenoid is a very simple electric switch controlled by a 12-volt source. See, even the Big Boy is not always called that. As an electronic tech I will refer to it as the relay. How's that for confusion.

So, Big Boy, Solenoid, Relay, and often because of the mfgr of these they are called Trombetta relays.

How these relays are activated can be complex or as simple as sending 12 volts and ground to them.

You will notice on your relay in the battery compartment that there are two wires. One is likely purple. In any case one is ground and the other is switched 12 volts. The purple wire is the switched voltage in most cases.

Again, 12 volts is sent to the purple wire and the big relay goes clunk and makes contact between the large wires thus combining the batteries.

That relay under normal working conditions will get very warm or even hot to the touch if it runs for several hours. For example, if things are working properly and you are using shoreline it will be working 24/7 and get hot to the touch. This is normal.

So, the heart of the system is that relay on the back being controlled by 12 volts. How and where that 12-volt control comes from can be the tricky part to understand...

We will get to the BIRD part shortly.

First, if the engine is running and after a few minutes of warming up and the grid heater stops loading down the battery voltage on the chassis batteries should rise enough to engage the BIRD device and send the 12 volts to the relay. This is the “Delay” part of the bird. It would not make sense to combine the batteries without the alternator having brought up chassis batteries a bit.

So, let’s take the situation where your chassis batteries have been run down for some reason. You left the radio on for two days etc.

Pressing and holding the Aux start button bypasses the fancy “BIRD” circuitry and sends 12 volts directly to the relay in the battery compartment.  This combines the battery banks just as a set of jumper cables would.

Now that we understand how the relay functions let’s begin managing when it is turned on. We already discussed how the “Aux” start button controls it. That is a manual function and can easily be tested by listening to the relay as someone presses the button. If no clunk is heard, then the relay is most likely already activated. To test this without a meter, simply remove the purple wire. Wear some gloves because there will be a tiny static like discharge that can surprise you. If you have a meter you can measure the voltage on the little terminals. You can also carefully feel the relay to see if it is warm or hot IF it has been engaged for some time.

Here is how the Bi-Directional Relay Delay functions to control that purple wire.

Keep in mind the “DELAY” part as you are troubleshooting. It can take a couple of minutes for it to activate. No sense in combining batteries if the first bank being charged is not up enough.

Parked with nothing running and no shoreline the bird is asleep. No combining. However, if you have solar that is indeed a charging source and may be enough to activate the bird.

Now you plug into shoreline. The little circuit board in the front run panel wakes up and sees that your converter is doing a fine job of charging the coach batteries. The converter is connected directly to them via cutoff switches and fuses or circuit breakers.  The BIRD now sends voltage to the relay and engages it, thus combining the batteries.

Time to leave, shoreline is disconnected so the BIRD drops out the control voltage. You fire up the big engine and in a couple of minutes the BIRD sees a nice alternator doing its thing. Time to send voltage to the relay again.  

We have just discussed the BI-directional part of the BIRD. This demonstrates how it can work from one set of battery banks to the other depending on which one is getting the charge.

Arriving at your favorite boon docking place you decide to fire up the generator to run some heavy loads. This generator is the same thing as having shoreline power, so it works as described before.

So, you spend the weekend without the generator running anymore and enjoy the quiet along with

some tv and perhaps running the microwave on the inverter. Inverter of course not the converter. They can be combined in one box and I can address that more if needed. Inverters are real battery hogs so now you have a very low set of batteries.

You are packed, and the big engine is started, thus providing a big enough voltage to activate the BIRD. You are now charging 6 batteries or more and the alternator is straining. This is rough on the alternator, so you follow the manufacture and my advice and fire up the generator so the “converter” comes alive and supplies voltage to the dead batteries.

At this stage you have two sources of charging voltage. The converter via the generator, and the alternator. This poses a bit of an issue with the alternator and can cause it to show a fault.  However, the BIRD is rather smart and knows the engine is running along with the generator. With these two competing charging sources it simply turns the Relay off and allows each battery bank to be charged separately.

Now that you understand how it works, here is a scenario that could get you home if your alternator dies. Just start the generator and prop the AUX button up so it forces the banks to combine. Since your alternator is offline there will not be any conflicts. This will easily get you any distance you wish to travel.

Of course, you could put a small jumper from 12 volts to the purple wire and do the same without pushing the button.

Now you understand how, when, and why the relay is activated. What you don’t know is if it is actually working. The relay is a very simple device inside. It is a magnet that pulls a contact across the two large wires connected to it. Very often these contacts burn and fail to make contact. This can be intermittent and drive a technician crazy.

If the relay is activated there is either a charging source or the AUX button is being held down. When it is activated it is like placing a nail across the two large terminals. So you should see the exact same voltage on each of the large terminals and at the batteries. If you do not see the exact same voltage across the large terminals, then the relay is bad.

This can be a bit tricky if both banks of batteries have been fully charged and the relay is making contact but a poor one. You will see the same voltage on each large terminal and think the relay is ok. You need to run one bank down a bit so there will be lots of current trying to charge for an accurate assessment.

If you are having one bank of batteries low after having a charging source for several hours and you find voltage on the purple wire then the relay is bad.,

These relays are a known source of problem and I had a heck of a time understanding how the system works. I am a senior certified electronic tech and extremely qualified to work on such a simple system as long as I know how it is supposed to function. I did not have that information in 2008.

Replacing the relay is easy and cheap as things go on these things. Be sure to turn both battery banks off and I would highly recommend removing the negative leads of each bank for additional safety. You can weld with these battery cables so do be careful.

Once you replace the relay do yourself and us a favor by taking it apart and posting pictures of the insides.

The actual BIRD control board is a common failure item too but has become difficult to source. I found one on e-bay.

Don’t despair if that is the problem because there are plenty of other solutions available.

There is another relay that has nothing to do with the charging system but gives plenty of problems. It is the “Salesman” switch/relay. It is the relay controlled by the switch by the door or nearby. The relay is in the box up front near the BIRD board. The BIRD board is a small board. The relay is on the bottom left.

This thing controls lots of functions and can go bad anytime. Simply bypassing it with a jumper is easy and permanent fix if it fails.

Keep in mind, things like the salesman solenoid and bird solenoid can be in different configurations. There are many of them so your snowflake may not match my description exactly. 

[Frank McElroy]

On 12/4/2022 at 7:52 AM, myrontruex said:

You are packed, and the big engine is started, thus providing a big enough voltage to activate the BIRD. You are now charging 6 batteries or more and the alternator is straining. This is rough on the alternator, so you follow the manufacture and my advice and fire up the generator so the “converter” comes alive and supplies voltage to the dead batteries.

At this stage you have two sources of charging voltage. The converter via the generator, and the alternator. This poses a bit of an issue with the alternator and can cause it to show a fault.  However, the BIRD is rather smart and knows the engine is running along with the generator. With these two competing charging sources it simply turns the Relay off and allows each battery bank to be charged separately.

Now that you understand how it works, here is a scenario that could get you home if your alternator dies. Just start the generator and prop the AUX button up so it forces the banks to combine. Since your alternator is offline there will not be any conflicts. This will easily get you any distance you wish to travel.

Of course, you could put a small jumper from 12 volts to the purple wire and do the same without pushing the button.

 

Myron, lots of good information but I need to make a few comments. 

Over the years there have been a number of "BIRD" control circuits used my Monaco.  My comments will focus on the combination BIRD and salesman switch latching relay(s) circuit board with remote salesman and battery boost switches used Dynasty and above model coaches starting in about 2005.  For reference, here is a link to a document in our files where I explained how to repair common failures on these boards.  This board is labelled PCB#6 and it's located in the Rear Run Bay.

 

The intellitec Big Boy that Monaco used was a non-latching Big Boy Battery Isolator Relay.  (I'm not aware of any instances were Monaco used the latching Big Boy Battery Disconnect.  The Blue Sea ML-ACR, a latching relay, is used by many folks to upgrade a failed BIRD/ Big Boy System.)

The control circuit board that I shown does not have a generator input signal.  Even though some of the other BIRD modules had a generator input signal, Monaco may or may not have used it.  The design reason for the generator input signal is to prevent applications with a AC to DC converter from being overloaded.  These converters were typically not smart chargers like the magnum inverter/chargers used in many Monaco coaches.  As for the issue with the ALT light coming on when both the generator and the alternator are producing power, that issue was resolved with the engine ECM via the J1939 data bus to the dash gauge cluster lighting up the dash ALT light when the engine wasn't seeing battery charging.  So, it didn't matter if the chassis batteries were being charged by the alternator or the generator through the Magnum inverter/charger.

If you had a weak engine alternator output, running the generator would automatically close the Big Boy and the chassis batteries would charge.  This is evidenced with the generator running by seeing the higher house AND chassis battery voltage when the Magnum was in bulk charge with the engine also running.  Like you mentioned, when the house batteries are low it's always good practice to first start the generator and let it run long enough so the Magnum goes into bulk charge, then start the engine.  Most of the battery charging will come from the Magnum and help save the life of the engine alternator.  Then when the bulk charge current drops off, the generator can be shut down and the engine alternator will take over.

It's important to know that when you press and hold the battery boost switch, a full 12 volts goes to the Big Boy solenoid.  The Big Boy solenoid is not designed to handle this amount of power for more than a few minutes.  That's why one of the terminals on the big boy solenoid coil has a voltage that is electronically modulated between 12 and 0 volts such that the average voltage is somewhere between 3-5 volts.  That modulation is why you hear the hum.  On the old BIRD Diesel-2 modules, the other side of the coil was grounded so the coil "hold in" voltage is around 3-5 volts.  On the design with the circuit board I illustrated, the other side of the coil is connected to +12 volts so the coil "hold in" voltage is around 8 volts.  The higher voltage didn't seem to cause any issues with burning up coils except that the big boy would run hotter but likely hold in the internal contacts a bit tighter. 

In practice, on coaches with the control circuit board I described, if your alternator fails, simply start your generator and turn on your charger.  Big Boy will engage and charge your chassis batteries. (If big boy fails, jumper the positive terminal on the house to chassis batteries - do not hold in the battery boost switch.)

On coaches with Big Boy, do not press and hold the battery boost switch for more than a few minutes at a time.  Otherwise you run the risk of burning up the Big Boy coil.

 

[Tom Cherry]

11 hours ago, Frank McElroy said:

Myron, lots of good information but I need to make a few comments. 

Over the years there have been a number of "BIRD" control circuits used my Monaco.  My comments will focus on the combination BIRD and salesman switch latching relay(s) circuit board with remote salesman and battery boost switches used Dynasty and above model coaches starting in about 2005.  For reference, here is a link to a document in our files where I explained how to repair common failures on these boards.  This board is labelled PCB#6 and it's located in the Rear Run Bay.

 

The intellitec Big Boy that Monaco used was a non-latching Big Boy Battery Isolator Relay.  (I'm not aware of any instances were Monaco used the latching Big Boy Battery Disconnect.  The Blue Sea ML-ACR, a latching relay, is used by many folks to upgrade a failed BIRD/ Big Boy System.)

The control circuit board that I shown does not have a generator input signal.  Even though some of the other BIRD modules had a generator input signal, Monaco may or may not have used it.  The design reason for the generator input signal is to prevent applications with a AC to DC converter from being overloaded.  These converters were typically not smart chargers like the magnum inverter/chargers used in many Monaco coaches.  As for the issue with the ALT light coming on when both the generator and the alternator are producing power, that issue was resolved with the engine ECM via the J1939 data bus to the dash gauge cluster lighting up the dash ALT light when the engine wasn't seeing battery charging.  So, it didn't matter if the chassis batteries were being charged by the alternator or the generator through the Magnum inverter/charger.

If you had a weak engine alternator output, running the generator would automatically close the Big Boy and the chassis batteries would charge.  This is evidenced with the generator running by seeing the higher house AND chassis battery voltage when the Magnum was in bulk charge with the engine also running.  Like you mentioned, when the house batteries are low it's always good practice to first start the generator and let it run long enough so the Magnum goes into bulk charge, then start the engine.  Most of the battery charging will come from the Magnum and help save the life of the engine alternator.  Then when the bulk charge current drops off, the generator can be shut down and the engine alternator will take over.

It's important to know that when you press and hold the battery boost switch, a full 12 volts goes to the Big Boy solenoid.  The Big Boy solenoid is not designed to handle this amount of power for more than a few minutes.  That's why one of the terminals on the big boy solenoid coil has a voltage that is electronically modulated between 12 and 0 volts such that the average voltage is somewhere between 3-5 volts.  That modulation is why you hear the hum.  On the old BIRD Diesel-2 modules, the other side of the coil was grounded so the coil "hold in" voltage is around 3-5 volts.  On the design with the circuit board I illustrated, the other side of the coil is connected to +12 volts so the coil "hold in" voltage is around 8 volts.  The higher voltage didn't seem to cause any issues with burning up coils except that the big boy would run hotter but likely hold in the internal contacts a bit tighter. 

In practice, on coaches with the control circuit board I described, if your alternator fails, simply start your generator and turn on your charger.  Big Boy will engage and charge your chassis batteries. (If big boy fails, jumper the positive terminal on the house to chassis batteries - do not hold in the battery boost switch.)

On coaches with Big Boy, do not press and hold the battery boost switch for more than a few minutes at a time.  Otherwise you run the risk of burning up the Big Boy coil.

 

As a followup to Frank’s post…which he is our resident expert and has also repaired defective Intellitec RC6(?) control board and has researched this and understands it, I also OFFER some info on the LOWER end coaches with the simple Intellitec BIRD or BIRD Diesel or the next generation BIRD DIESEL2 module that controls the Big Boy.  Basically, the Big Boy didn’t change….but technology and Monaco and experimentation did.

I THINK that Monaco started using the BIRD DIESEL circa 2005 or 06.  I helped a member with an 06 Windsor “BIRD” and it was a different circuit configuration from the 08/09 Camelots.  I spent a lot of time with the original, now deceased, Intellitec tech guy.  When he passed away, Intellitec turned over the tech support to M&M. At one time, we were weekly friends.  They also winter in Florida and do work.  They have attended several Gatherings and answered questions and made presentations as well as do some repair work.

First….and foremost,  NEVER, EVER Jimmy or wedge the Boost Switch.  Maybe the Trombetta will be OK,  but applying full 12+ VDC to the coil for several minutes will toast the coil.  Every Monaco manual warns against that.  

Next up….for the NON Dynasty (and higher) MH that have the Big Boy and a “BIRD” module, here is some tech info and such directly from Intellitec’s in-house tech. I have assisted at least 20 folks over the years and their problems were easy to spot using the trouble shooting guidelines that the Intellitec guy gave me,

Frank and I also discussed the “holding” voltage that the Big Boy needs…as well as the “common sense” touchy/feely tests.  Here is what I understand.  The Dynasty control board runs at a higher voltage than the Intellitec BIRD module supplies.  WHY…Frank has done a lot of research.  Who knows.  But, the holding voltage is different.  The Dynasty has the “equivalent” of an 8 VDC or so potential.  Intellitec told me to measure across the control terminals of the Big Boy and if it was in the 3 - 5 VDC arrange….that meant the BIRD module was working.  Mine runs a smidge over 3…some folks get high 3….I don’t recall any 4’s.  BUT, that is sufficient to operate properly.  NOW….my Big Boy is barely WARM…but it does have at least a 15 degree delta T.  In the summer, when the ambient is high, it is warm.  Frank’s, per our discussion, is a hand warmer and you are uncomfortable if you hold it for a period of time.  Dumb logic.  His has a pulsed 8 VDC control.  It hums…it is hot.  Mine has 3.2 or so and when the outside temp is 50 dF, you can barely feel the delta T and it is not “noisy”.  

The reason for pointing out is that one needs to know WHICH type of controller is in use and what the operating and voltage parameters are.

Next up is a discussion of the evolution of the BIRD DIESEL into the DIESEL2. On the 2006 Windsor, there was a Generator (presumably RUN) wire to the Genny terminal on the BIRD DIESEL.  On my 2009, that input or wire is NOT used.  We asked M&M and they said….don’t matter and that was the end of that.  They DID SAY that it was OK, generically for any “Monaco” to be plugged in, have the Genny on and running the engine.  I rarely do that as it is possible when you kill the shore and the AC is ON, for the Genny to shut down as it has not warmed up and the brief disconnect and then connect to the Genny via the ATS causes a fault.

BUT….I can also tell you HOW to determine if your Big Boy is working as you drive…. If your house batteries are down a smidge from operating the slides, odds are the Magnum will try to recharge and you get a higher voltage BULK rate for a while.  If I need the AC on, then my first priority is to start the Genny and get it warmed up.  Then I do my pre-start routine and eventually start the engine.  I have a digital VM on the main display.  The Leece Neville puts out 13.8/13.9….rarely 14.0.  So after the Cummins ECM allows full charging or run voltage it settles in at 13.8/.9.  

BUT, if the Magnum is not recharging at BULK….my DC (display) voltage read a few tenths ABOVE 14.  Sometimes 14.4.  SO, I know that the Big Boy is engaged and the Magnum is controlling the voltage.  BUT….I do NOT have a Genny wire attached to my BIRD DIESEL2.  So, maybe if it was configured with a Genny input, it might drop out the Big Boy…

Final trouble shooting for the Big Boy for those without a clamp on Ammeter.  If the Big Boy “feels” warm or is humming from a Dynasty control board, then do a Ground to Each Terminal test.  The voltage should be within 0.05 (5 hundreds).  If it is higher on one side, then there is probably some corrosion or pitting of the contacts.  

Next, measure the coil (small terminals) voltage.  With the BIRD DIESEL2, it should be within 3 - 5 VDC.  

Next, use the OHM or continuity….across the studs.  Should be a circuit.  Finally, back on volts, test the voltage across the studs….should be zero or less than 0.05 (five hundred).

if all is well……..great.  You can also disconnect all shore power.  Then reconnect and quickly go to the RRB where the Big Boy is and it should go CLUNK…maybe a minute or so delay based on the ATS setting….

FINALLY, thanks to Frank’s input, I actually am resting my Big Boy in storage this year.  Read the latter part of my post on how I did it.

 

The first photo is or was the test.  I had a 9” and a 12” Jumper or #2 gauge cable.  I bolted them together and used a piece of 1” PVC as an insulator.  I installed it like the first photo and did my voltage tests.  BINGO…I found the elusive 0.3-0.5 VDC drop that has eluded me for years.  Then I found that the cable was too fat for the battery door to close properly, so i rerouted it.  The second or right photo is how it is now…

 

[Bill R]

7 hours ago, Tom Cherry said:

On the 2006 Windsor, there was a Generator (presumably RUN) wire to the Genny terminal on the BIRD DIESEL.

You are correct Tom, as usual.  The 2006 Windsor BIRD picks up the GEN RUN HR signal as the indicator that the Generator is running.

[VinceB]

I know this is an older thread but...

I have (I think) a similar issue.  I notice after driving, my house batteries are at only 12.5v according to the panel.  When the big engine is running, I assume that the voltage should jump up to 13.5 or so as when the generator is running. Testing across the isolator terminals confirms the alternator is not charging the house batteries.

This makes me think my isolator is not working.  Here's a pic of what I have. They are available on the web and 1 is on the way.

My question is am I on the right track? Or could it be something else? I don't know that I have a BIRD board (?)

 

[Ivylog]

With the engine running do you have 12V to the small wires on the solenoid…energized? Where do the small wires go? Doubt you have a BIRD.

Edited January 27, 2023 by Ivylog

[Frank Bergamo]

Your picture is not an isolator. That looks like the battery boost solenoid. Here is a link to what you.probably have, https://www.motorcityreman.com/2-165.html?cmp=googleproducts&kw=2-165&gclid=EAIaIQobChMIh__c6c_m_AIVWQ2tBh0CVATqEAQYAiABEgLmMPD_BwE. Look around on the internet for a better price. Hope this helps.

[VinceB]

I'll have to check.

2 hours ago, Ivylog said:

With the engine running do you have 12V to the small wires on the solenoid…energized? Where do the small wires go? Doubt you have a BIRD.

I'll have to check

49 minutes ago, Frank Bergamo said:

Your picture is not an isolator. That looks like the battery boost solenoid. Here is a link to what you.probably have, https://www.motorcityreman.com/2-165.html?cmp=googleproducts&kw=2-165&gclid=EAIaIQobChMIh__c6c_m_AIVWQ2tBh0CVATqEAQYAiABEgLmMPD_BwE. Look around on the internet for a better price. Hope this helps.

Thanks for the response but there is nothing like that on my coach.

[VinceB]

55 minutes ago, Frank Bergamo said:

Your picture is not an isolator. That looks like the battery boost solenoid. Here is a link to what you.probably have, https://www.motorcityreman.com/2-165.html?cmp=googleproducts&kw=2-165&gclid=EAIaIQobChMIh__c6c_m_AIVWQ2tBh0CVATqEAQYAiABEgLmMPD_BwE. Look around on the internet for a better price. Hope this helps.

I'm no electrical whiz, but COULD the following be the theory of operation...?

At rest, the banks are isolated. Dry camping would never run down the chassis batteries this way. On a start attempt of the big engine, the battery banks are not tied together unless you hit the AUX switch.

After big engine start, 12v is sent to the solenoid to tie the banks together so they both charge.

FYI & FWIW, neither the generator nor shore power ever did charge the chassis battery bank. I had to install a Xantrex Echo to solve that problem. Also an FYI, I could start the generator, hit the AUX switch and start the big engine if the chassis bank was insufficient. I used that trick in cold weather to get a better cranking RPM.

So perhaps Monaco was getting double function out of this solenoid as a cheap way to do things in a low-tech way?

 

 

 

[Tom Cherry]

34 minutes ago, VinceB said:

I'm no electrical whiz, but COULD the following be the theory of operation...?

At rest, the banks are isolated. Dry camping would never run down the chassis batteries this way. On a start attempt of the big engine, the battery banks are not tied together unless you hit the AUX switch.

After big engine start, 12v is sent to the solenoid to tie the banks together so they both charge.

FYI & FWIW, neither the generator nor shore power ever did charge the chassis battery bank. I had to install a Xantrex Echo to solve that problem. Also an FYI, I could start the generator, hit the AUX switch and start the big engine if the chassis bank was insufficient. I used that trick in cold weather to get a better cranking RPM.

So perhaps Monaco was getting double function out of this solenoid as a cheap way to do things in a low-tech way?

 

 

 

Sort of YES and NO...

YES....there is NO charging of the Chassis when camping and having Genny or Shore.  That was always a big issue.  The Xantrex Echo should do the trick....but not being up on it's specs.....all you need to charge or maintain the Chassis is a THREE STAGE (Desulfonator option is nice).  Once you get the Chassis Charged, it takes less than 2 amps to maintain them.  Some have put on cheap 6/12 chargers and never shut off and cooked their Chassis Battery....so read up and understand.  You only NEED a little current to maintain.  That overcomes the normal parasitic load.

Isolator.  The device that was in the link....and you don't (not saying NO) think you have it.  It is NEEDED or necessary or was originally INSTALLED from the factory.  If you READ the info, they basically do NOT start charging the House until after the engine (Diesel) is running.  Intellitec makes one....

https://intellitec.com/isolator-relay-delay/

Thus, there are BIG ones (like the link) and smaller ones.....What you need to do is get a VOM and start to troubleshoot and understand.  When you let the Diesel warm up for a few minutes, the Isolator relay is SUPPOSED to send a 12 VDC signal to the Boost Solenoid in your picture.  Then you get the banks connected and you get DUAL charging.  If you had the Intelltiec BIRD system, you would then get a BiDirectional charging.  So, when the genny or Shore was on.....you charge BOTH banks.  Likewise....when you drive....you get BOTH.  NOW, you CAN install a BIRD module.  BUT, The original BIRD Module would be the one.  The later Diesel 2 was designed for lower voltage.  I am NOT sure how your White Roberts is rated...as to what the lock in or holding voltage is.  If you get the PN off it, you can find out....

As far as LOW TECH... it was a matter of "State of the Art in Development".  The isolator delay kept the house batteries charged whilst driving....a VERY IMPORTANT feature.  As technology and design engineers kept working on it....they developed the BIRD system. Circa 2007, it was the Diesel2 BIRD system that Monaco used.  That solved it....

OK....a word of caution or education.  The White Rogers will blow it contact up....unless you understand and use caution.  You CAN use the Boost to start the Genny.....assuming your HOUSE bank ain't totally DEAD.  The boost (logical ...very LOGICAL) gets its Power (Source) from the HOUSE....so you can use it to ASSIST the Engine.  BUT, if the House set is dead, it AIN"T gonna have any 12 VDC to energize the coil and use the Chassis to start the Genny.  A JUMPER cable is needed between the TWO banks (POSITIVE ONLY).  Once you get the Genny started....then you are charging the House.  BUT....in that situation, the House bank is woefully INADEQUATE.  YES....the Inverter is pumping 80 Amps or more into the batteries.  OPPS....it takes almost 1400 AMPS from the Chassis bank to turn over Big Bertha Diesel Mama.  SO, you have let the House get recharged somewhat, otherwise you will really deep cycle (as in DEEP SIX) the Deep Cycle House....so KNOW THAT AND BE CAREFUL.

NOW....what you were doing, with a fully or reasonably well charged House Bank to ASSIST is fine.  BUT....KNOW THIS.  If you read the Manual....it says (paraphrasing) that you need to HAVE SOME VOLTAGE in the Chassis Bank.  That is why the tell you to HOLD ON THE BOOST for a period of time....and put a surface charge on the Chassis.  THEN, you CAN use....with knowledge and caution....the Boost Switch to start the Chassis.  OK....this a a LOT....

BUT....to keep it simple....  You will need a helper..  Have someone turn on the ignition.  Then have them PRESS the Boost Switch.  Measure the VOLTAGE across the small coils.  That should be 12 VDC or maybe a bit higher.  You should ALSO here a CLICK or CLUNK that shows it is engaged.  NOW....measure the voltage (DC) across the large Terminals with the engine running and the BOOST switch PUSHED ON.  You should see less than maybe 0.2 or 0.1....in a perfect world, it would be 0.05 or less.  That means that there is NO voltage drop across the large contacts.  OK....if that is FINE....you have then TESTED the Boost Solenoid.  You KNOW it works when you use the Boost switch.

NOW....let the engine run....and also release the BOOST.  The SAME thing should be happening....wherever the Isolator Delay or Isolator Boost "device" is, it SHOULD be sending 12 VDC to the terminals on the Boost Solenoid.....JUST LIKE IT DID WITH THE BOOST ON.  If no control or 12 VDC then the Isolator Device....is DEFECTIVE....and needs to be replaced.

Finally....When the ENGINE is running....what is the VOLTAGE (Chassis Bank) across the TERMINALS (Positive and Negative. YES....you are correct...it should be in the 13.5 of higher range.  If it ain't and is only 12.5....then there is a problem with the Voltage Regulator and/or Alternator.  NOW....carry that one step further....as you SAID, the Boost Solenoid should be ENGAGED when the engine if running....so if so...and there is barely a small voltage drop across the studs...then the HOUSE should be close to the SAME voltage as the Chassis.  That is how it works..  Noodle it over...

Good Luck....let us know what you find...

[VinceB]

16 hours ago, Tom Cherry said:

Sort of YES and NO...

YES....there is NO charging of the Chassis when camping and having Genny or Shore.  That was always a big issue.  The Xantrex Echo should do the trick....but not being up on it's specs.....all you need to charge or maintain the Chassis is a THREE STAGE (Desulfonator option is nice).  Once you get the Chassis Charged, it takes less than 2 amps to maintain them.  Some have put on cheap 6/12 chargers and never shut off and cooked their Chassis Battery....so read up and understand.  You only NEED a little current to maintain.  That overcomes the normal parasitic load.

Isolator.  The device that was in the link....and you don't (not saying NO) think you have it.  It is NEEDED or necessary or was originally INSTALLED from the factory.  If you READ the info, they basically do NOT start charging the House until after the engine (Diesel) is running.  Intellitec makes one....

https://intellitec.com/isolator-relay-delay/

Thus, there are BIG ones (like the link) and smaller ones.....What you need to do is get a VOM and start to troubleshoot and understand.  When you let the Diesel warm up for a few minutes, the Isolator relay is SUPPOSED to send a 12 VDC signal to the Boost Solenoid in your picture.  Then you get the banks connected and you get DUAL charging.  If you had the Intelltiec BIRD system, you would then get a BiDirectional charging.  So, when the genny or Shore was on.....you charge BOTH banks.  Likewise....when you drive....you get BOTH.  NOW, you CAN install a BIRD module.  BUT, The original BIRD Module would be the one.  The later Diesel 2 was designed for lower voltage.  I am NOT sure how your White Roberts is rated...as to what the lock in or holding voltage is.  If you get the PN off it, you can find out....

As far as LOW TECH... it was a matter of "State of the Art in Development".  The isolator delay kept the house batteries charged whilst driving....a VERY IMPORTANT feature.  As technology and design engineers kept working on it....they developed the BIRD system. Circa 2007, it was the Diesel2 BIRD system that Monaco used.  That solved it....

OK....a word of caution or education.  The White Rogers will blow it contact up....unless you understand and use caution.  You CAN use the Boost to start the Genny.....assuming your HOUSE bank ain't totally DEAD.  The boost (logical ...very LOGICAL) gets its Power (Source) from the HOUSE....so you can use it to ASSIST the Engine.  BUT, if the House set is dead, it AIN"T gonna have any 12 VDC to energize the coil and use the Chassis to start the Genny.  A JUMPER cable is needed between the TWO banks (POSITIVE ONLY).  Once you get the Genny started....then you are charging the House.  BUT....in that situation, the House bank is woefully INADEQUATE.  YES....the Inverter is pumping 80 Amps or more into the batteries.  OPPS....it takes almost 1400 AMPS from the Chassis bank to turn over Big Bertha Diesel Mama.  SO, you have let the House get recharged somewhat, otherwise you will really deep cycle (as in DEEP SIX) the Deep Cycle House....so KNOW THAT AND BE CAREFUL.

NOW....what you were doing, with a fully or reasonably well charged House Bank to ASSIST is fine.  BUT....KNOW THIS.  If you read the Manual....it says (paraphrasing) that you need to HAVE SOME VOLTAGE in the Chassis Bank.  That is why the tell you to HOLD ON THE BOOST for a period of time....and put a surface charge on the Chassis.  THEN, you CAN use....with knowledge and caution....the Boost Switch to start the Chassis.  OK....this a a LOT....

BUT....to keep it simple....  You will need a helper..  Have someone turn on the ignition.  Then have them PRESS the Boost Switch.  Measure the VOLTAGE across the small coils.  That should be 12 VDC or maybe a bit higher.  You should ALSO here a CLICK or CLUNK that shows it is engaged.  NOW....measure the voltage (DC) across the large Terminals with the engine running and the BOOST switch PUSHED ON.  You should see less than maybe 0.2 or 0.1....in a perfect world, it would be 0.05 or less.  That means that there is NO voltage drop across the large contacts.  OK....if that is FINE....you have then TESTED the Boost Solenoid.  You KNOW it works when you use the Boost switch.

NOW....let the engine run....and also release the BOOST.  The SAME thing should be happening....wherever the Isolator Delay or Isolator Boost "device" is, it SHOULD be sending 12 VDC to the terminals on the Boost Solenoid.....JUST LIKE IT DID WITH THE BOOST ON.  If no control or 12 VDC then the Isolator Device....is DEFECTIVE....and needs to be replaced.

Finally....When the ENGINE is running....what is the VOLTAGE (Chassis Bank) across the TERMINALS (Positive and Negative. YES....you are correct...it should be in the 13.5 of higher range.  If it ain't and is only 12.5....then there is a problem with the Voltage Regulator and/or Alternator.  NOW....carry that one step further....as you SAID, the Boost Solenoid should be ENGAGED when the engine if running....so if so...and there is barely a small voltage drop across the studs...then the HOUSE should be close to the SAME voltage as the Chassis.  That is how it works..  Noodle it over...

Good Luck....let us know what you find...

Thanks for the detailed response. I will let you know what I find but it will take a while as I have to wait for the paint shop to complete the final paint correction, paint awnings and re-install, and paint the window/door frames.  Should have it back next week but...