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Onan Generator - Electric system failure


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When gen running all is good for around 2 min then the amps drawing changes to 86 amps to much for gen,and kills it.

What maybe causing this?

same on shore power.

2006 holiday rambler endeavor

IMG_1727 bulk charging.JPG

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Your panel is showing charging amps of 86 for your batteries. Check your batteries with a hydrometer to see if you have dead cells or shorted.

Tim

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That's a lot of amps but thats 12v and your gen is putting out 120v so your gen would only need to put out 8.6 amps at 120v.  If I figured that right something else is killing you gen.   I remember something about a setting I believe in your charger settings that will stop the gen when they reach charged.

Richard knows this stuff, maybe he can chime in.  Or anyone else that has an idea.

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5 minutes ago, Ray Davis said:

That's a lot of amps but thats 12v and your gen is putting out 120v so your gen would only need to put out 8.6 amps at 120v.  If I figured that right something else is killing you gen.   I remember something about a setting I believe in your charger settings that will stop the gen when they reach charged.

Richard knows this stuff, maybe he can chime in.  Or anyone else that has an idea.

Yes, check your invertor control panel and make sure it's not set to auto start/stop the generator for battery state of charge. Look in your manual for the RC7/GS

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3 minutes ago, Tim-AZ said:

Yes, check your invertor control panel and make sure it's not set to auto start/stop the generator for battery state of charge. Look in your manual for the RC7/GS

There you go, someone with a memory. I should-a known you would know.  What was I thinking?

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Is there a blinking light fault on your generator control switch after this shutdown?   That would indicate to me that there is some kind of short circuit in your 120vac system, something that does not 'kick in' as soon as ac power is put on the system.   Maybe an air conditioner??

 

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I had a similar issue,  gen would shut off in a few minutes.  It was the water pump belt that was broken.  My light was out so I didn't look for codes and it was cold so no big deal. Figured it out after arriving home. Our 7500 generators uses a special belt, Onan only. 

Edited by Ray Davis
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8 hours ago, bigbhb said:

reset the magnum and all is working .

thank you for the help

Brian

Assuming you did a soft reset, holding the power button ON for 15-20 seconds, and then releasing.  Yes,that will clear out the gremlins.  
The Intellitec EMS reads the Neutral, so you had 9.6 amps going to the charger, call it 10…so you did not have any other major loads…

Glad the reset worked.  What I can tell you is that the Genny sensed a load that it could not handle.  I had the same issue, but  it was a with a higher load.  I inadvertently left on the AC when breaking camp.  I unplugged power.  Then started the Genny from the button on it.  I would have thought that the 2 minute delay on the AC system would have kicked in and not allow them to run.  That was many years ago.  Memory says that, but I may have started the Genny and then pulled power.  It shut off.  It would NOT restart….or maybe run for a minute or two.  I was driving and just let it sit…almost like some timer or whatever was wrong had to clear itself out.  About 30 minutes later, I started it.  Let it run for a few minutes….then had DW turn on one AC…wait….then the other.  Have not had that issue since.

My comment would be to check the Magnum setup and make sure the parameters were set properly.  The key ones are 30 amp on shore, disable search watts, set LBC to 11.8 VDC..depending on which remote you have that might not let you adjust and 11.0 is the max.  Charging rate should be at 80% …sometimes I use 70% when the batteries are low.  AC cutoff to 100 VAC.  Check the battery amp hours and type.

Good luck.

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  • Tom Cherry changed the title to Onan Generator - Electric system failure
On 8/15/2022 at 9:52 AM, Tim-AZ said:

Your panel is showing charging amps of 86 for your batteries. Check your batteries with a hydrometer to see if you have dead cells or shorted.

Tim

Don't believe that's too out of line while bulk charging.

I know I've seen at least high 70's, and I only have my charge rate set to 70%.

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When my AGS kicks on my panel will sometimes show 100+ amps for a short time, and then start decreasing after a while.  I have 4 batteries rated at 20 Hour Rate: 420.  I’m wondering if that 100 amps gets divided by 4, so there is 25 amps going to each battery?

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16 minutes ago, dandick66 said:

When my AGS kicks on my panel will sometimes show 100+ amps for a short time, and then start decreasing after a while.  I have 4 batteries rated at 20 Hour Rate: 420.  I’m wondering if that 100 amps gets divided by 4, so there is 25 amps going to each battery?

Nope.  You have TWO batteries in SERIES....  That means that the current going through them is like having ONE 12 VDC.  Therefore you have 50 Amps through each bank.  Your TWO "12VDC" or equivalent batteries....the TWO in series, are in parallel....then the 100 amps is divided, IN THEORY, by half.  In reality, it may be different depending on the state of charge....but for talking purposes, it is the same.

NOW....to continue with my old EE-101.  IF there is a bad cell or issues in ONE or BOTH of the two batteries in series (CONNECTED TOGETHER), then that is a higher resistance and that bank will suck up MORE, which is essentially wasted as it does NOT end up as stored energy.

THAT.....is why one needs to know the condition of each cell (assuming you have regular and not "MAINTENCANCE FREE" batteries....as well as doing a voltage check of EACH BATTERY.  If you lose a CELL....like I did when the coating on the cell plates dropped off enough to short it out, you will only get around 4.5 VDC when you measure that battery.  IF you have a bad cell, which shows up as a DUD or way below the Specific Gravity value....it MAY still be getting charged....but not gonna work. The voltage will still be 6.X VDC....but, again, the juice going into that cell is wasted.

CASE IN POINT.  I had one battery in one bank or series that had a shorted cell.  4.5 VDC.  I also had, in the other bank, a bad cell in one battery.  BOTH were toast and the charging was flaky.  I moved the two good ones into ONE (Series connected) Bank or 2 Batteries which would be a 12 VDC.  I ditched the other two. I was fine with them, but I only had 225 Amp Hours and not the 450 Amp Hours I would have had with a full bank of four.

Hope this makes sense....GOOD QUESTION...

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6 minutes ago, Tom Cherry said:

Nope.  You have TWO batteries in SERIES....  That means that the current going through them is like having ONE 12 VDC.  Therefore you have 50 Amps through each bank.  Your TWO "12VDC" or equivalent batteries....the TWO in series, are in parallel....then the 100 amps is divided, IN THEORY, by half.  In reality, it may be different depending on the state of charge....but for talking purposes, it is the same.

NOW....to continue with my old EE-101.  IF there is a bad cell or issues in ONE or BOTH of the two batteries in series (CONNECTED TOGETHER), then that is a higher resistance and that bank will suck up MORE, which is essentially wasted as it does NOT end up as stored energy.

THAT.....is why one needs to know the condition of each cell (assuming you have regular and not "MAINTENCANCE FREE" batteries....as well as doing a voltage check of EACH BATTERY.  If you lose a CELL....like I did when the coating on the cell plates dropped off enough to short it out, you will only get around 4.5 VDC when you measure that battery.  IF you have a bad cell, which shows up as a DUD or way below the Specific Gravity value....it MAY still be getting charged....but not gonna work. The voltage will still be 6.X VDC....but, again, the juice going into that cell is wasted.

CASE IN POINT.  I had one battery in one bank or series that had a shorted cell.  4.5 VDC.  I also had, in the other bank, a bad cell in one battery.  BOTH were toast and the charging was flaky.  I moved the two good ones into ONE (Series connected) Bank or 2 Batteries which would be a 12 VDC.  I ditched the other two. I was fine with them, but I only had 225 Amp Hours and not the 450 Amp Hours I would have had with a full bank of four.

Hope this makes sense....GOOD QUESTION...

I should have remembered about connecting batteries in series and parallel and the associated voltage and current.  My head was “somewhere else”.  
Before I replaced all 4 batteries, I did have a bad one and did what you did, just wired 2 batteries in series.  It worked fine until they finally gave out. 

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Sulfate particles will fall off the lead plates collecting in the bottom of the battery.  In older battery's the particles will collect in the bottom of the battery.  Then the particles will raise up causing a short across the lead plates that will make the battery explode.  Not worth saving dollars delaying the change out.  When changing batteries, change out the entire set.

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  • 1 month later...

This code 27 on 10 and 12.5kw untits has to do with the electrical part, not engine itself but is does cause the fuel actuator to shut off. I had that code and it turned into an expensive repair. If you lucky, it could be just a connection issue. If you download service manual and have a good meter, there are tests to check windings and brushes through the connectors etc. Basically the code says that it does not sense good AC power. Try running it with breaker OFF first, if not already.

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58 minutes ago, ph1386 said:

04 executive with a 10k onan. I am getting code 27. Generator starts for about 5 seconds and then dies. Any ideas what I can look for? Thanks 

Merged the new thread into an existing one for more information.

https://www.cummins.com/rv-generator-manuals

See your manual and the codes are in there.  Otherwise, the above will allow you to download the proper manual for your Revision letter.

https://manuals.heartlandowners.org/manuals/Electrical/Generator/Onan 5500/Onan Troubleshooting Codes.pdf

The above is also a good reference.

https://www.flightsystems.com/pdf/onan-rv-troubleshooting-guide.pdf

IF you have a bad board, which is common due to moisture, Flight Systems is one of the most common sources for remanufactured boards.  Many techs carry the 10 KW boards due to issues....

 

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On mine, there are 2 wires with spade connectors running across the air cage between motor and generator. These 2 would stop the engine. Easily accessible and visible from the side opening. There are 2 connectors at the bottom of intake muffler where the controller is mounted. Then an other 1 or 2 between the maze of hoses under air filter with wires coming out of the stator opening.

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What Ivan said!

I had to partially remove the top cover to get access to them.

Front of generator, passenger side. Once you get your top cover loosened up enough to remove the small front section of top cover, you will see them.

Mine had 3 or 4 spade connectors.

If none have come apart, you will still need to get at them to continue the troubleshooting on that fault.

Edited by 96 EVO
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