Very bizarre generator problem

[John C]

2 hours ago, Tom Cherry said:

Back up.  What you need to understand is the relationship of the AMPS and VOLTAGE.  You “sort of” defined your problem…and it is, as I posted, a HIGH RESISTANCE issue.  Frank also instructed you, just as I did to reboot your Intellitec MPX.  I do NOT think you have a control issue, but you must understand and troubleshoot properly.

Just because you have higher…as in 13.6 VDC when on shore…..that does not mean that you have fully charged or good batteries.  That is the Magnum in FLOAT MODE.

Then, when you unplug from shore, you have 12.7 VDC. I think we have been down this path before and it is important that you learn and understand how Amps and Volts and Current Draw impacts each other or what to expect under load…..if not, then you will be chasing ghosts and really unhappy with your Motor Home.

OK…NOW…you have “good” or reasonable Voltage at the Chassis Bank.  However, your statememt about holding the switch too long is incorrect.  You have to understand WHERE to measure and what to expect.

JUST to confirm….when you say “connectors to the engine”….you actually mean the Generator Starting Studs….or where the 12 VDC is attached.  You said the voltage was 10 - 11.5 VDC…I HOPE that was when you pressed the switch….The Generator “studs” should measure at least 12 VDC and crank instantly.  So, you have low or inadequate voltage.

BUT….If I UNDERSTAND…..you have NO VOLTAGE on the studs when the Generator is just sitting idle. That is totally inconsistent….  First you said 13.6 on shore…then 12.7 when off shore…..then low…too low 10 - 11.5.. WHEN you start an engine, the amp draw will be from the “resistance” in the starter windings and YES…the voltage will drop.  BUT you have to read or measure the voltage at the starter connection….which is the two 12 VDC studs on the rear.  If you have inadequate…as in the batteries are not fully charged (12.7 can be a surface charge….we’ve discussed that before) and then if they are weak, the voltage will drop like a stone.

SO…if you want assistance, then please perform the tests as outlined and not do additional pne or become helter skelter.  It is impossible to reach a logical conclusion.

My request was very specific and would have isolated some issues.  Go back and read my post.  Hook up a pair of Jumper cables to the two studs (engine) and then use the front (on the generator’ switch.  We have to “remove” or eliminate the starter controls (inside and on the MPX).  Do that.  I suspect it will start quickly……..then report back.

THEN you can start following the correct troubleshooting for the voltage issues….not COMPLICATED….you, your wife and your VOM….but once we know that the Generator will start with an auxiliary battery….we can proceed and quit guessing or speculating…

Thanks,,,,

 

There are to connector I test for voltage, the first one is from the coach to the outside box of the generator, that is 12.7V when no connected to the shore power. This voltage is very consistent.

After I open the generator box cover, there are 3 connectors outside of the generator ENGINE, I honestly don't know which one is which, so I chose the two connectors just to see if I could measure the voltage going into the generator.

It is normal that will be no voltage going into the engine when the switch outside the generator is NOT pressed.

I did get voltage when I pressed the voltage. that went from 0->9v->10->11v->, because multi-meter pins on the connector are not very stable and the voltage measurement on the engine kept changing(depends on pressure and movement of the multi-meter pins), so I didn't get very stable voltage.

 

7 minutes ago, Frank McElroy said:

If you are saying that with the voltmeter is connected to the battery cables on the back of the generator, the voltage goes to zero when you press the start switch on the generator, it means you either have dead coach batteries, or high resistance in one of 12 volt cables from the chassis battery bank or the ground cable connecting the generator to the chassis frame is bad.

First try connecting the voltmeter ground to the chassis frame, not the ground lug on the generator.  A loose generator ground cable would show the voltage readings you are seeing provided your voltmeter was actually on the +12 and ground connections on the generator.

Sorry I didn't make myself clear.

There are two connectors I test for voltage, the first one is from the coach to the outside box of the generator, that is 12.7V when no connected to the shore power. This voltage is very consistent.

After I open the generator box cover, there are 3 connectors outside of the generator ENGINE, I honestly don't know which one is which, so I chose the two connectors just to see if I could measure the voltage going into the generator.

It is normal that will be no voltage going into the engine when the switch outside the generator is NOT pressed.

I did get voltage when I pressed the voltage. that went from 0->9v->10->11v->, because multi-meter pins on the connector are not very stable and the voltage measurement on the engine kept changing(depends on pressure and movement of the multi-meter pins), so I didn't get very stable voltage.

[MyronTruex]

19 hours ago, John C said:

No sure if it was because of the temperature, Here in So California, it is about 67 degrees when I was doing it...

Notice that even the big engine has a grid heater or something of the like. Diesel pickups have a wait to start. Or the ones I recall. So the failure of one or more glow plugs could easily lead to longer starting/warm up times. I experienced this while living in Northern Ca. with similar temps. 

[Frank McElroy]

The battery connections you want to test are on the BACK of the generator where the large +12 and Ground cables are connected.

[John C]

22 minutes ago, Frank McElroy said:

The battery connections you want to test are on the BACK of the generator where the large +12 and Ground cables are connected.

Yes, I did test that connection and that one is very consistent 12.7V when unplugged

[Tom Cherry]

32 minutes ago, MyronTruex said:

Notice that even the big engine has a grid heater or something of the like. Diesel pickups have a wait to start. Or the ones I recall. So the failure of one or more glow plugs could easily lead to longer starting/warm up times. I experienced this while living in Northern Ca. with similar temps. 

YES.... But his data or measurements are a contradiction.  He reports ZERO Volts when the switch is NOT pushed but earlier a low voltage.

You MAY be RIGHT....that would account for the lower voltage... BUT until he tries the GREAT VOLTAGE trick with Jumper Cables....or says NO...tell ME HOW to PROPERLY MEASURE... it is all theory.

We need to know the Voltage, under the INTIAL Load,  at the Chassis Bank...when the front switch is pushed.  That tells us if the problem is in the battery.

Next, we need to know the Voltage, under the Initial Load, at the Connections up front...

Then FINALLY, we need to know the Voltage, under the Initial Load, at the genny studs.

THEN, we can determine the issue...

26 minutes ago, Frank McElroy said:

The battery connections you want to test are on the BACK of the generator where the large +12 and Ground cables are connected.

John,

Your terminology and posts are confusing, at least to me.

The points you are measuring are "meaningless", at least to me, without a picture.  BUT, from what you said, you have a VOLTAGE ISSUE in the HIGH AMP Starting cables....  The FRONT switch takes the "starting circuit" out of the picture.  We do NOT need to be messing with that until we establish, which was posted a few times before, what the voltage is on the TWO CABLES connected to the REAR (you do NOT have to remove the cabinet).  The TWO Studs on the back.

If that voltage is LOW or insufficient...it ain't gonna start.  The reason for telling you to MEASURE THERE and use the UP FRONT SWITCH is that the INTERNAL switches are OUT of the PICTURE.  If you don't have sufficient battery voltage or if there is a voltage drop (high resistance or too small cables), then the issue is that..

Please see the post that I just made.

Either USE the Jumper Cables as outlined several posts ago.... and try to start it from the FRONT GENNY SWITCH... not a harness or the internal switches

OR....

Read the REST of my last posts and measure the voltage, when your wife pushes the start button on the GENNY, directly...  We need to know, when the button is pushed....the voltage at the Chassis....  Then at the FRB where the Cables to the Genny are connected....and FINALLY, the connection (studs) on the Genny.

ODDS ARE....your batteries are OK...but we don't KNOW THAT.  Odds are...the cables are OK UP FRONT and there is enough Voltage...but we DON'T KNOW THAT.

ODDS ARE...when you finally test or measure the Voltage on the Genny's studs....it is gonna BE LOW....to LOW.  THEN... The fix will be replacing the cables....but jumping around and measuring voltage at some undefined (at least to me) point tells us nothing,

Hope this explains it.....Use the JUMPER CABLES....that is the quickest and easiest....

NOW....VERY IMPORTANT...  Have your PRIMED the Genny?  You hold the button DOWN (on the front panel)....that preheats the GLOW PLUG....hold it down for maybe 45 second....  Do this EVERY TIME you attempt to start...  
 

YES....HOLD it down when you use the Jumper Cables....

Good Luck.  Perform the tests as outlined....it is the ONLY WAY myself or others can logically and definitavely TELL YOU WHAT IS WRONG.

15 minutes ago, John C said:

Yes, I did test that connection and that one is very consistent 12.7V when unplugged

BUT....we need to know this when your wife holds down the button to start... ODDS ARE...it is gonna drop like a ROCK.  The Jumper Cables gives you GOOD VOLTAGE THERE>>>and it should START...OTHERWISE, there is an internal issue....but we need to verify voltages....test and measure....before we say....have the Genny REPAIRED....

Please read and reread the importance of what data and tests we need....otherwise, these posts are futile....

[Frank McElroy]

3 hours ago, John C said:

Yes, I did test that connection and that one is very consistent 12.7V when unplugged

Since you confirmed that you are getting 12.7 volt power to the generator, my best advice is for you to follow the trouble shooting section 12.7 in the Onan service manual. 

BUT - PLEASE FIRST POST THE BATTERY VOLTAGE WHILE PRESSING THE START SWITCH ON THE GENERATOR WITH THE VOLTMETER CONNECTED TO THE GENERATOR POSITIVE AND NEGATIVE BATTERY TERMINALS AT THE BACK OF THE GENERATOR.

See sections 12-1 and 12-2 on pages 61 and 62 in the attached Onan manuals link - you want the service manual. 

Earlier, I attached a Monaco schematic of the remote controls including the Intellitec interface.

 

[MyronTruex]

Frank is getting right to the heart of it. Get to the wires on the back of the generator. Showing 12.7 volts on them without the generator turning over is nearly useless information. Not quite though.

IF your voltage as measured right in the middle of the bolts holding the wires drops, then you need to get your voltmeter negative lead to a clean ground and put your positive lead in the middle of the negative bolt on the generator. IF any voltage shows up while cranking and you are measuring the ground post, you have a bad ground.

Don't use the wire terminals of the wires to make the measurements. You need to dig the meter into the bolts ends. I actually sharpen my voltmeter probes to nearly a needle sharpness. Yes this can play heck with my fingers but it really assures me of getting a good measurement.

IF you can't find a decent ground for the meter. Use a wire brush or sandpaper and make one. You need to be sure your measurements are valid.

 

[Frank McElroy]

18 minutes ago, MyronTruex said:

Frank is getting right to the heart of it. Get to the wires on the back of the generator. Showing 12.7 volts on them without the generator turning over is nearly useless information. Not quite though.

IF your voltage as measured right in the middle of the bolts holding the wires drops, then you need to get your voltmeter negative lead to a clean ground and put your positive lead in the middle of the negative bolt on the generator. IF any voltage shows up while cranking and you are measuring the ground post, you have a bad ground.

Don't use the wire terminals of the wires to make the measurements. You need to dig the meter into the bolts ends. I actually sharpen my voltmeter probes to nearly a needle sharpness. Yes this can play heck with my fingers but it really assures me of getting a good measurement.

IF you can't find a decent ground for the meter. Use a wire brush or sandpaper and make one. You need to be sure your measurements are valid.

 

Exactly.  Until John posts real data under load, the 12.7 volt measurement means nothing. Unless he has a voltage measurement between the +12 and ground connections at the generator (not frame ground) he has not proven that the generator is seeing 12 volts while the generator is starting.

[Tom Cherry]

39 minutes ago, Frank McElroy said:

Exactly.  Until John posts real data under load, the 12.7 volt measurement means nothing. Unless he has a voltage measurement between the +12 and ground connections at the generator (not frame ground) he has not proven that the generator is seeing 12 volts while the generator is starting.

 

1 hour ago, MyronTruex said:

Frank is getting right to the heart of it. Get to the wires on the back of the generator. Showing 12.7 volts on them without the generator turning over is nearly useless information. Not quite though.

IF your voltage as measured right in the middle of the bolts holding the wires drops, then you need to get your voltmeter negative lead to a clean ground and put your positive lead in the middle of the negative bolt on the generator. IF any voltage shows up while cranking and you are measuring the ground post, you have a bad ground.

Don't use the wire terminals of the wires to make the measurements. You need to dig the meter into the bolts ends. I actually sharpen my voltmeter probes to nearly a needle sharpness. Yes this can play heck with my fingers but it really assures me of getting a good measurement.

IF you can't find a decent ground for the meter. Use a wire brush or sandpaper and make one. You need to be sure your measurements are valid.

 

What is so frustrating is that the OP was given the exact instructions for doing just that... that was about 24 hours ago...and they have been repeated several times....there have been over 20 posts since then.,

It is very difficult to troubleshoot or provide assistance when direct and well laid out instructions are not followed....and then helter skelter information, sometimes conflicting, is presented.

It is requested, based on my conversation with Frank on this matter earlier this afternoon, that we let this topic SIT and then wait until John responds....as requested.

That way, there will be no further confusing or supeerfulous posts...  Those of us following and trying to assist can then review and proceed.

Myron....thanks for your insight into this...it helps members stay focused... and this topic had reached the point of "being put on HOLD"

 

[John C]

2 hours ago, Frank McElroy said:

Since you confirmed that you are getting 12.7 volt power to the generator, my best advice is for you to follow the trouble shooting section 12.7 in the Onan service manual. 

BUT - PLEASE FIRST POST THE BATTERY VOLTAGE WHILE PRESSING THE START SWITCH ON THE GENERATOR WITH THE VOLTMETER CONNECTED TO THE GENERATOR POSITIVE AND NEGATIVE BATTERY TERMINALS AT THE BACK OF THE GENERATOR.

See sections 12-1 and 12-2 on pages 61 and 62 in the attached Onan manuals link - you want the service manual. 

Earlier, I attached a Monaco schematic of the remote controls including the Intellitec interface.

 

Yes, I looked at the manual, but the problem is I am having a hard time locate the P8 harness connector

 

2 hours ago, Frank McElroy said:

Exactly.  Until John posts real data under load, the 12.7 volt measurement means nothing. Unless he has a voltage measurement between the +12 and ground connections at the generator (not frame ground) he has not proven that the generator is seeing 12 volts while the generator is starting.

OK, Frank @Frank McElroy, I just crawled under the coach and tested the voltage again, this time when DW was pushing the start, here is the voltage

12.4V -before DW push the start button outside the generator

11.4V to 11.7V- kept hearing the click Click

8V to 9V-> heard the crank sound , this last very short period of time, probably 1 second or less

11.4V to 11.7V- kept hear the click Click

8V to 9V-> heard the crank sound , this last very short period of time, probably 1 second or less

12.4v -> Generator started

I didn't time this, seems to be very long, definitely more than 10 seconds

Please let me know what you think.

Thank you

 

 

1 hour ago, Tom Cherry said:

 

What is so frustrating is that the OP was given the exact instructions for doing just that... that was about 24 hours ago...and they have been repeated several times....there have been over 20 posts since then.,

It is very difficult to troubleshoot or provide assistance when direct and well laid out instructions are not followed....and then helter skelter information, sometimes conflicting, is presented.

It is requested, based on my conversation with Frank on this matter earlier this afternoon, that we let this topic SIT and then wait until John responds....as requested.

That way, there will be no further confusing or supeerfulous posts...  Those of us following and trying to assist can then review and proceed.

Myron....thanks for your insight into this...it helps members stay focused... and this topic had reached the point of "being put on HOLD"

 

Sorry I have not retired yet, still need to work to make ends meet.

I need to find time after work to crawl under the coach, I also needs to wait when DW is home to help me push the switches.

[Frank McElroy]

3 minutes ago, John C said:

Yes, I looked at the manual, but the problem is I am having a hard time locate the P8 harness connector

 

OK, Frank @Frank McElroy, I just crawled under the coach and tested the voltage again, this time when DW was pushing the start, here is the voltage

12.4V -before DW push the start button outside the generator

11.4V to 11.7V- kept hearing the click Click

8V to 9V-> heard the crank sound , this last very short period of time, probably 1 second or less

11.4V to 11.7V- kept hear the click Click

8V to 9V-> heard the crank sound , this last very short period of time, probably 1 second or less

12.4v -> Generator started

I didn't time this, seems to be very long, definitely more than 10 seconds

Please let me know what you think.

Thank you

 

 

You have a voltage drop problem like Tom Cherry thought early on.  Please go back and reread his earlier posts.  A bad cable connection, bad batteries, or bad ground.  Check cables for a voltage drop like Myron suggested.

[John C]

On 3/14/2024 at 5:58 PM, Tom Cherry said:

OPPS...  Again...an ASSUMPTION.  The Genny Start system is integrated into the MPX system.  WHOLE NEW BALL GAME as to Controls.  THAT also explains WHY your VOM, I THINK, caused the "Bizarre" situation....that is assuming that ALL the Gen Start Switches are on the LIGHTED MPX Panel.

IN THE FUTURE...  PLEASE state where any funky SWITCH is located.  IT DOES MAKE A DIFFERENCE...MOST folks are NOT attuned to such...as we have "PLAIN JANE SWITCHES"

OK....NOW to your issues.

I STILL SUPSECT VOLTAGE ISSUES....so that needs to be addressed FIRST.  The best way to tell...  RUN A JUMPER CABLE.

SO...here is what you do.  Move your Vehicle near the GENNY so you can get jumper cables underneath or on the BACK two studs of the Genny.

NOW....do this exactly as written. 

TURN OFF THE BATTERY CUT OFF SWITCH at the DOOR

TURN OFF the DISCONNECT SWITCHES....both HOUSE and CHASSIS. 

Then Hook up the POSITIVE and the NEGATIVE (Jumper Cables) to the Genny battery cable terminals.  YES...they are a bit small...but will work.

NOW...  THEN scoot out and HOOK up the jumper cables...(MINDFUL of the POLARITY) to your car or whatever vehicle.

THEN...  TURN ON BOTH House Disconnect switches.  Wait a minute or so.  

THEN...  Turn on the Battery Cutoff switch.  That will reboot your CPU and the Intellitec MPX.

NOW...  wait about 5 minutes.  Test a light or a fan or the water pump or any switches on any of the LIGHTED Key pads...

DID THAT RESOLVE THE GENNY SWITCH in the Bedroom.  IF NOT...then that is a DIFFERENT ISSUE...I think...

NOW...  Go to the FRONT of the Generator or move the Genny Slide out.  IT COULD have been out before...which ever is easier.  Push the START SWITCH on the PANEL or the UP FRONT CONTROL box.  IT should START instantly.

That means that you have GOOD POWER to the Genny (from the vehicle) to Start.

Let it run for about 5 minutes and THEN shut it off from the inside....say the dash or wherever the front (near the cockpit) lighted switch panel is. THAT SHOULD WORK...  BUT REPORT WHAT DOES and WHAT DOES NOT WORK.

OK....wait about 5 minutes for the Genny to cool off.  NOW try the Genny Switch up front.  I THINK it will start FINE.  IF SO....then we have isolated the issue as a HIGH RESISTANCE connection or STUPID UNDERSIZED cables.

NOW…..turn off the disconnect switchs.  Then remove the jumper cables….then turn the switches back on…..

You STILL need to clean the Battery Stud Grounds at the back.  You STILL need to clean the ground cable up front to whereever it is GROUNDED....as well as where the Positive it.  If that don't fix it.  GET NEW CABLES....

NOW... Here is where I hand you off.  @Frank McElroy needs to chime in here if you have lights or issues with the MPX switches.  I THINK that when you use the VOM....it actually "sent a signal" to start... BUT, I am at a LOSS at to WHERE you have the VOM.  Maybe Frank can noodle it out. What I told you to do is how you TROUBLE SHOOT Voltage issues....

The Genny SHOULD start with good voltage from the vehicle and using the UP FRONT Switch is NOT part of the MPX system...

 

Tom @Tom Cherry

Could you please tell me when you disconnect the jumper cable? after you turn on the house disconnect? or the Jumper cable is always connected during the whole process?

Please advise.

Thank you.

[Tom Cherry]

6 minutes ago, John C said:

Yes, I looked at the manual, but the problem is I am having a hard time locate the P8 harness connector

 

OK, Frank @Frank McElroy, I just crawled under the coach and tested the voltage again, this time when DW was pushing the start, here is the voltage

12.4V -before DW push the start button outside the generator

11.4V to 11.7V- kept hearing the click Click

8V to 9V-> heard the crank sound , this last very short period of time, probably 1 second or less

11.4V to 11.7V- kept hear the click Click

8V to 9V-> heard the crank sound , this last very short period of time, probably 1 second or less

12.4v -> Generator started

I didn't time this, seems to be very long, definitely more than 10 seconds

Please let me know what you think.

Thank you

 

 

Sorry I have not retired yet, still need to work to make ends meet.

I need to find time after work to crawl under the coach, I also needs to wait when DW is home to help me push the switches.

Very SIMPLE.  You do NOT have enough battery or VOLTAGE to start the generator.  Use my JUMPER method.  It will start in an Instant.  This is what we have been needing….to KEEP you from working on something that is NOT BROKE.

FIRST….read the manual and make sure you know how to prime the system (heat the glow plug and get the fuel pressure up).  Prime the Genny for 30 seconds…..

NOW that we know there is a Voltage problem, you must chase it down.  I have some “gut feels”, but you must perform the tests.

Measure Voltage, while your wife tries to start…using the front generator switch…

Meter leads - VOM on Chassis bank.  Test and record. 

Meter leads on the cable ends….the cables from the Generator studs, back of generator….follow these cables to the side or front where the Negative is grounded to the chassis and where the POSITIVE is connected to the stud or post in the Front Run Bay.  Have her do the start again….  Test snd record….

Post those readings.

FINAL TESTS…  have your wife outside….as usual.  Then sit in the drivers seat.  Hold down the BOOST BUTTON. Signal your wife to start the Genny…..how long did that take or “was there an improvement?”….

Next….start the engine….let it run for about 5 minutes.  The voltage will be low, in the 12’s…..when the chassis voltage jumps up to around the high 13’s or maybe even 14…..HOLD DOWN the BOOST Button….signal your wife…..

NOW include the results of using the Boost with and without the engine running.  Did THAT FIX IT?

Once you do this….and do it when convenient tomorrow….I’m signing off due to a HOME committment.  Get your tests run over the weekend and let us know….

We need this to advise HOW to fix it,…and it will not, if I’m right….anything ultra expensive…

ONE FINAL Question?  Look on the Chassis Battery.  Is there some date such as Month and Year?  If not?  Is there a stamped year date (maybe 2 digits) on the lead posts or around the terminals?  Need that, if available, as well….

We’re GETTING THERE….

 

8 minutes ago, John C said:

Tom @Tom Cherry

Could you please tell me when you disconnect the jumper cable? after you turn on the house disconnect? or the Jumper cable is always connected during the whole process?

Please advise.

Thank you.

Go back and read the original post…..here is the edit that I did…..

OK....wait about 5 minutes for the Genny to cool off.  NOW try the Genny Switch up front.  I THINK it will start FINE.  IF SO....then we have isolated the issue as a HIGH RESISTANCE connection or STUPID UNDERSIZED cables.

NOW…..turn off the disconnect switchs.  Then remove the jumper cables….then turn the switches back on…..

You STILL need to clean the Battery Stud Grounds at the back.  You STILL need to clean the ground cable up front to whereever it is GROUNDED....as well as where the Positive it.  If that don't fix it.  GET NEW CABLES....

NOW…hope that makes it clear….

Good luck….

[John C]

1 hour ago, Tom Cherry said:

Very SIMPLE.  You do NOT have enough battery or VOLTAGE to start the generator.  Use my JUMPER method.  It will start in an Instant.  This is what we have been needing….to KEEP you from working on something that is NOT BROKE.

FIRST….read the manual and make sure you know how to prime the system (heat the glow plug and get the fuel pressure up).  Prime the Genny for 30 seconds…..

NOW that we know there is a Voltage problem, you must chase it down.  I have some “gut feels”, but you must perform the tests.

Measure Voltage, while your wife tries to start…using the front generator switch…

Meter leads - VOM on Chassis bank.  Test and record. 

Meter leads on the cable ends….the cables from the Generator studs, back of generator….follow these cables to the side or front where the Negative is grounded to the chassis and where the POSITIVE is connected to the stud or post in the Front Run Bay.  Have her do the start again….  Test snd record….

Post those readings.

FINAL TESTS…  have your wife outside….as usual.  Then sit in the drivers seat.  Hold down the BOOST BUTTON. Signal your wife to start the Genny…..how long did that take or “was there an improvement?”….

Next….start the engine….let it run for about 5 minutes.  The voltage will be low, in the 12’s…..when the chassis voltage jumps up to around the high 13’s or maybe even 14…..HOLD DOWN the BOOST Button….signal your wife…..

NOW include the results of using the Boost with and without the engine running.  Did THAT FIX IT?

Once you do this….and do it when convenient tomorrow….I’m signing off due to a HOME committment.  Get your tests run over the weekend and let us know….

We need this to advise HOW to fix it,…and it will not, if I’m right….anything ultra expensive…

ONE FINAL Question?  Look on the Chassis Battery.  Is there some date such as Month and Year?  If not?  Is there a stamped year date (maybe 2 digits) on the lead posts or around the terminals?  Need that, if available, as well….

We’re GETTING THERE….

 

Tom @Tom Cherry

Could you please tell me when you disconnect the jumper cable? after you turn on the house disconnect? or the Jumper cable is always connected during the whole process?

I just test the boost, looks like it is much fast now probably half of the time than it was before.

Does that looks like a battery problem?

I have not trace the cable yet.

[Tom Cherry]

11 hours ago, John C said:

Tom @Tom Cherry

Could you please tell me when you disconnect the jumper cable? after you turn on the house disconnect? or the Jumper cable is always connected during the whole process?

I just test the boost, looks like it is much fast now probably half of the time than it was before.

Does that looks like a battery problem?

I have not trace the cable yet.

John,

You have a LACK of voltage.  You need to understand that when you start ANY engine, the compression of the cylinders, unless it has a “compression release”, has to be “overcome” by the torque (rotation power….called pound feet” of the starter to “spin” the engine causes the battery voltage to drop….

NOW, if you had say 5 chassis batteries in a bank…..the engine would spin faster that with 2 or 3 or 1.

So…when you have a battery (batteries) that do not have sufficient “Cold Cranking Amps”, then the engine will barely or slowly turn over….in your case…..

You do NOT have sufficient voltage to the generator starter to start the generator.

When you use the boost, you have the house bank (4 or 8 ) in parallel with the Chassis.  Frank and I have had many conversations and you MAY have one or two conditions prevalent.  

ALL THE JUMPER CABLE test was to provide a “full power” BATTERY to test to see if the issue was internal (generator) or if it was merely a lack of good or adequate cranking power.  SO….since the boost works….lets forget the Jumper cables….

Frank’s 08 Dynasty has the same cabling arrangement.  He says that from time to time as his Chassis Battery starts to “normally get weaker”, he notices that the Genny starts “slower” and he may decide to use the boost.  NOW, the Chassis bank STILL starts the engine.  
 

We, Frank and I, both have the same engine.  We also use the same “Rule of Thumb” test.  When our chassis gets more than say 4 years old, we pay more attention. For example….it is hot…say above 90 degrees and we drive a few hours and stop.  We will wait maybe 5 - 10 minutes.  That period is when the engine, after it is shut down and coolant is not flowing, gets HOTTER….as in the compression will be at a Peak.  Then, with the DASH HVAC on in the AC max mode, we start the engine.  If it fires up….no delay….great. BUT, when there is that OMG…IT AIN’T GONNA START….or dead silence and the engine has NOT turned over…..then you panic….but BINGO…it starts….then we KNOW to replace the Chassis battery in a year or so.

OK….the above was long…..but…until you do the REST of the tests….we do NOT KNOW whether you have chassis batteries that are starting to get weaker or if there is a “connection point” that is loose or corroded or if it is the MONACO GOOF and you need to replace the cables from the FRT RUN BAY to the studs on the Genny.

NOW…reread and measure the voltage, while attempting to crank, at the following points. Unplug the shore power so we can get GOOD and clean readings.  The Big Boy and Charger will be ON and we do NOT want that.

Chassis Battery bank.  Record the “at rest” or just sitting voltage.  Then have your wife, up front, hold the start button….then after maybe 5 seconds note the battery voltage.

Find the GROUND cable up front that goes to the Negative Stud on the Genny. Find the Positive stud or where the Positive is connected inside the FRT RUN BAY.  HOPEFULLY….you can put a meter probe on each…..if NOT….find a good GROUND inside the FRONT RUN BAY….or use a bolt head (sort of scratch an X in it with the probe or a knife so you can use that for a ground.  NOW measure the at rest voltage….record it.  Repeat the attempt to start and record the voltage after 5 or so seconds.

Finally, repeat the test by measuring at the Generator Studs…..at rest….then start.

IT IS IMPORTANT that we know the AT REST or no load voltage at each point,

DO THAT…report back. 

ODDS ARE….it is TWO things….your chassis is not as good as it once was….and the voltage drop across the puny, undersized #2 cables going to the Genny is now taking a greater toll…as in,the weaker the chassis, the worse, exponentially, the voltage drop AT THE GENNY STUDS will be.

NOW….there is also ONE MORE EXPERIMENT…..

Use Jumper cables.  Run the positive from the Genny Stud to the OTHER END of the positive cable….where it bolts or is connected in the FRB….

Run a Jumper cable from the negative to where the Negative cable is connected to the ground stud….

THEN….put your meter leads on the genny studs…..measure the voltage….at rest.  Then have your wife crank it and see if the voltage is higher or doesn’t drop as fast…it MIGHT even crank much faster….

THAT tells us how much of the issue is in the puny cables.  

TO EXPLAIN…..#2 Copper has a max value of 130 Amps….  The Cold Cranking Amps on ONE of your Chassis Batteries is 950…..so….since you have two that is 1900 Amps.  The MAX Amps that the #2 will deliver is 130 A or barely 6%.  BUT a 2/00 (00) cable will deliver 195 Amps or 50% more.  If you run supplemental jumper cables, that tells us, as well as shows you, how much improvement you will get by recabling…

GO FOR IT when convenient 

[John C]

7 hours ago, Tom Cherry said:

John,

You have a LACK of voltage.  You need to understand that when you start ANY engine, the compression of the cylinders, unless it has a “compression release”, has to be “overcome” by the torque (rotation power….called pound feet” of the starter to “spin” the engine causes the battery voltage to drop….

NOW, if you had say 5 chassis batteries in a bank…..the engine would spin faster that with 2 or 3 or 1.

So…when you have a battery (batteries) that do not have sufficient “Cold Cranking Amps”, then the engine will barely or slowly turn over….in your case…..

You do NOT have sufficient voltage to the generator starter to start the generator.

When you use the boost, you have the house bank (4 or 8 ) in parallel with the Chassis.  Frank and I have had many conversations and you MAY have one or two conditions prevalent.  

ALL THE JUMPER CABLE test was to provide a “full power” BATTERY to test to see if the issue was internal (generator) or if it was merely a lack of good or adequate cranking power.  SO….since the boost works….lets forget the Jumper cables….

Frank’s 08 Dynasty has the same cabling arrangement.  He says that from time to time as his Chassis Battery starts to “normally get weaker”, he notices that the Genny starts “slower” and he may decide to use the boost.  NOW, the Chassis bank STILL starts the engine.  
 

We, Frank and I, both have the same engine.  We also use the same “Rule of Thumb” test.  When our chassis gets more than say 4 years old, we pay more attention. For example….it is hot…say above 90 degrees and we drive a few hours and stop.  We will wait maybe 5 - 10 minutes.  That period is when the engine, after it is shut down and coolant is not flowing, gets HOTTER….as in the compression will be at a Peak.  Then, with the DASH HVAC on in the AC max mode, we start the engine.  If it fires up….no delay….great. BUT, when there is that OMG…IT AIN’T GONNA START….or dead silence and the engine has NOT turned over…..then you panic….but BINGO…it starts….then we KNOW to replace the Chassis battery in a year or so.

OK….the above was long…..but…until you do the REST of the tests….we do NOT KNOW whether you have chassis batteries that are starting to get weaker or if there is a “connection point” that is loose or corroded or if it is the MONACO GOOF and you need to replace the cables from the FRT RUN BAY to the studs on the Genny.

NOW…reread and measure the voltage, while attempting to crank, at the following points. Unplug the shore power so we can get GOOD and clean readings.  The Big Boy and Charger will be ON and we do NOT want that.

Chassis Battery bank.  Record the “at rest” or just sitting voltage.  Then have your wife, up front, hold the start button….then after maybe 5 seconds note the battery voltage.

Find the GROUND cable up front that goes to the Negative Stud on the Genny. Find the Positive stud or where the Positive is connected inside the FRT RUN BAY.  HOPEFULLY….you can put a meter probe on each…..if NOT….find a good GROUND inside the FRONT RUN BAY….or use a bolt head (sort of scratch an X in it with the probe or a knife so you can use that for a ground.  NOW measure the at rest voltage….record it.  Repeat the attempt to start and record the voltage after 5 or so seconds.

Finally, repeat the test by measuring at the Generator Studs…..at rest….then start.

IT IS IMPORTANT that we know the AT REST or no load voltage at each point,

DO THAT…report back. 

ODDS ARE….it is TWO things….your chassis is not as good as it once was….and the voltage drop across the puny, undersized #2 cables going to the Genny is now taking a greater toll…as in,the weaker the chassis, the worse, exponentially, the voltage drop AT THE GENNY STUDS will be.

NOW….there is also ONE MORE EXPERIMENT…..

Use Jumper cables.  Run the positive from the Genny Stud to the OTHER END of the positive cable….where it bolts or is connected in the FRB….

Run a Jumper cable from the negative to where the Negative cable is connected to the ground stud….

THEN….put your meter leads on the genny studs…..measure the voltage….at rest.  Then have your wife crank it and see if the voltage is higher or doesn’t drop as fast…it MIGHT even crank much faster….

THAT tells us how much of the issue is in the puny cables.  

TO EXPLAIN…..#2 Copper has a max value of 130 Amps….  The Cold Cranking Amps on ONE of your Chassis Batteries is 950…..so….since you have two that is 1900 Amps.  The MAX Amps that the #2 will deliver is 130 A or barely 6%.  BUT a 2/00 (00) cable will deliver 195 Amps or 50% more.  If you run supplemental jumper cables, that tells us, as well as shows you, how much improvement you will get by recabling…

GO FOR IT when convenient 

Tom,

Under the guidance of Frank today, he helped me found out that my Big Boy is not charging the chassis battery, I spent the whole morning remove the Big Boy and clean inside really good. now the I just installed the Big Boy back and it is charging the chassis battery now.

I will let it charge for the rest ot today and will try it first thing tomorrow morning and report back.

Thank you.

 

[Frank Bergamo]

Yep, that Big Boy will get you if you are not on top of it! 

[Tom Cherry]

Looks good to me.  But….after you get your chassis charged, you STILL have no idea as to whether you have a connection or a cabling issue…..nor do you have any quantitative measurement of the condition of your chassis batteries…..

you can spend half the time it took to clean the Big Boy and do the measurements.  If you had done that, then the voltage measurements on the first step, would have shown undercharged or poor condition Chassis.  Then the next step….verify the BIRD system is working and that the BIG BOY is clean and functioning.

So…let the Big Boy do its trick.  Recharge the Chassis…   But….you need to know the condition of the Chassis bank and the load (as in starting the genny) will tell us that.  Maybe OK…MAYBE NOT…

You don’t want to replace good chassis….nor do you want to depend on bad ones. The genny start test is an excellent method.

BUT….REGARDLESS OF THAT….It is a KNOWN issue….and Frank and I discussed and agree. He just lives with it and says he will eventually recable….just not a priority.  My point is IDENTIFY what is wrong.  Folks have needlessly put in expensive “motorcycle” batteries that were not needed…only a simple and fairly inexpensive set of the correct 00 or even 000 cables.

Let us know….

 

[MyronTruex]

Watching the voltage drop as the glow plugs suck a lot of current and then having the starter engage and pull the voltage really low quickly shows you have a supply problem/ground.

Even if it started after doing trying a couple  of times, the heavy glow plug current may have shut off because of the heated area from previous tries allows the glow plugs to shut off, and the tiny bit extra voltage allows you to start it.

Get those probes sharpened and measure the voltage at the center of the bolts/stud. And ground your meter to a shiny place when you test the negative post. This simple test will tell you if you have a bad ground, along with an obvious poor supply voltage.

[John C]

3 hours ago, Tom Cherry said:

Looks good to me.  But….after you get your chassis charged, you STILL have no idea as to whether you have a connection or a cabling issue…..nor do you have any quantitative measurement of the condition of your chassis batteries…..

you can spend half the time it took to clean the Big Boy and do the measurements.  If you had done that, then the voltage measurements on the first step, would have shown undercharged or poor condition Chassis.  Then the next step….verify the BIRD system is working and that the BIG BOY is clean and functioning.

So…let the Big Boy do its trick.  Recharge the Chassis…   But….you need to know the condition of the Chassis bank and the load (as in starting the genny) will tell us that.  Maybe OK…MAYBE NOT…

You don’t want to replace good chassis….nor do you want to depend on bad ones. The genny start test is an excellent method.

BUT….REGARDLESS OF THAT….It is a KNOWN issue….and Frank and I discussed and agree. He just lives with it and says he will eventually recable….just not a priority.  My point is IDENTIFY what is wrong.  Folks have needlessly put in expensive “motorcycle” batteries that were not needed…only a simple and fairly inexpensive set of the correct 00 or even 000 cables.

Let us know….

 

After a couple of hours charging, I unplugged the shore power, started the generator under 7 seconds!

Tried 4 times, everything were like that. I am going to charge it all night tonight. and I will try it tomorrow, maybe it will take even less time to start tomorrow. Will report it back.

Thank you guys so much for the help.

I really appreciate it.

[MyronTruex]

The higher the voltage, the higher the wattage consumed by the glow plugs. 

I really would love to see the voltage readings now. Just a volt or two can make a serious difference. Low voltage alone can confuse electronics. 

[Tom Cherry]

10 hours ago, John C said:

After a couple of hours charging, I unplugged the shore power, started the generator under 7 seconds!

Tried 4 times, everything were like that. I am going to charge it all night tonight. and I will try it tomorrow, maybe it will take even less time to start tomorrow. Will report it back.

Thank you guys so much for the help.

I really appreciate it.

Do the three voltage tests.  Then post the results.  Remember to measure first at each point…..then have your wife crank and the drop.

We’ll know instantly if you have good batteries and also how much the puny, Monaco GOOFED #2 cables are impacting you.

You may be FINE??  IN ADDITION…. I ALWAYS “PRIME” my Genny as the older they get, the more they seem to need it.  A GOOD tech will NOT take your word.  He will PRIME IT….wait a minute or so….then TEST.

BTW…I’ll bet the internal switches work.  That is why I have been insistent on IDENTIFYING the problem before you try to work on or fix something that AIN’T BROKE!

[amphi_sc]

I'd be curious about how well the AGS starts the generator ... I was thinking back to the question I asked a while back why I would never hear the generator crank when the AGS started it as it just always fired off ... never would notice a crank just popped to life immediately.  But when I'd try a manual start with the switch it would crank 4, 5 or more times before firing off.  It was suggested the AGS primed it and I wasn't manually priming it by holding the generator stop button for a while before pressing the start. Anyway, just curious following this thread.  (By the way your BigBoy wasn't as badly green as mine was last time I did the annual cleaning.  I probably should make it a semi annual routine ...)

[Ivan K]

51 minutes ago, amphi_sc said:

I'd be curious about how well the AGS starts the generator ... I was thinking back to the question I asked a while back why I would never hear the generator crank when the AGS started it as it just always fired off ... never would notice a crank just popped to life immediately.  But when I'd try a manual start with the switch it would crank 4, 5 or more times before firing off.  It was suggested the AGS primed it and I wasn't manually priming it by holding the generator stop button for a while before pressing the start. Anyway, just curious following this thread.  (By the way your BigBoy wasn't as badly green as mine was last time I did the annual cleaning.  I probably should make it a semi annual routine ...)

Our Trace inverter preheats/prime the generator for 15s, then 2s pause, then cranks.

[John C]

On 3/17/2024 at 6:22 AM, Tom Cherry said:

Do the three voltage tests.  Then post the results.  Remember to measure first at each point…..then have your wife crank and the drop.

We’ll know instantly if you have good batteries and also how much the puny, Monaco GOOFED #2 cables are impacting you.

You may be FINE??  IN ADDITION…. I ALWAYS “PRIME” my Genny as the older they get, the more they seem to need it.  A GOOD tech will NOT take your word.  He will PRIME IT….wait a minute or so….then TEST.

BTW…I’ll bet the internal switches work.  That is why I have been insistent on IDENTIFYING the problem before you try to work on or fix something that AIN’T BROKE!

Yesterday the ground is still wet because of the rain on Saturday so I didn't get a chance to crawling under the coach.

Just test it today.

The battery started at 1.35v (right after I unplugged it from shore power)

Pushed the generator,it dropped to 12.68v and stayed there for 4-5 seconds.

I heard the crank, the voltage drop to 9.68v for one second

Generator start!!!

The voltage came back 12-13v(didn't pay too much attention this point so I don't have the exact number).

 

So after two days charging, it started under 6 seconds

The inside keypad switch works now, I believe that was not "working" because I made the same mistake by releasing the keypad too soon(Just like I released the switch outside the generator too soon).

The only problem right now is the keypad light is reversed, the generator light on keypad is one when generator is not started, and it is off when Gen Started.

It looks like a wiring issue and I am not going to worry about that for now because I have so many major things to work on the coach now.

 

Thanks again for all your help.

John