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Topic: Generator problem??? (Read 659 times) previous topic - next topic

Generator problem???

I have just fixed my Onan Emerald III propane generator - I thought.  The biggest problem was the lack of brush contact with the slip rings.  I seem to have some other problem, however.  I was dry camping at the Circuit of the Americas in Austin while working there and I thought I was charging the house battery with the generator but it appears that I wasn't.  I have disconnected the power supply in the dump valve compartment since I have been told that it will over charge the house battery.  I thought from reading the Onan manual that the generator should charge the house battery but I get no increase in voltage on the monitor with the generator running and had to run the main engine to keep the house battery up.  Should I have seen an increase in voltage on the monitor with the generator running?  If so, what sort of current does the generator provide to the house battery?  Where does the DC come from to charge the battery?  Is it the diode bridge on the control board?  BTW, I had just purchased a new house battery that week.
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Generator problem???

Reply #1 –
Not sure, but I thought that the house batteries are charged off the 120 volt battery charger that the generator provides power thru the transfer switch.  Now I will have to see it the generator is making 12 volt DC and 120 volt AC.

And how was the camping at the Circuit?  Saw the place from the toll road and Google Earth looks huge.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: Generator problem???

Reply #2 –
Poor brush contact pressure is due either poor spring condition due to over heating, this is generally caused by overload.  Could also be from dirt binding up the brush in the holder.
Should not be a biggie, just clean the holder/brush rig, so brush floats freely, do not spray a miracle cure all on it. just remove and clean, if springs look heated/weak,  replace em.
As to the load, Onan has no control over how you wire into the generator.
Cheers
Dave M

Re: Generator problem???

Reply #3 –
The generator should power the converter/charger which in turn charges the house batteries and powers the 12V system in the coach. To see if the converter is working, disconnect the house battery and see if your 12V interior lights still work. You may have a bad converter/charger or it may have come unplugged.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Generator problem???

Reply #4 –
Quote
I have disconnected the power supply in the dump valve compartment since I have been told that it will over charge the house battery.
You need to plug this back in - that's really the only thing that will charge your house batteries (shore power or with generator running).  Yes, it is true that these old "converters" can overcharge but I believe that is only when they malfunction.  Replacement with a modern 3 stage charger will be better for your batteries and they will also recharge the batteries faster - thus minimizing generator run time when you boondock.
Note: some generators will have a small alternator on the engine.  If yours has one it will provide some charging to the batteries but it's really made for just charging a separate (small) battery dedicated to the generator - of which most motorhomes (Foretravel included) will not have installed.  The separate battery would normally be install for an application like a house backup system.  Running your generator without the converter plugged in will overload that little alternator with a depleted house battery bank load on it and it might burn it up.  Same situation as to why you shouldn't try to charge your house batteries on just the main engine alternator - although with just the engine idling I don't think the alternator will put out it's maximum current so I would think it would be O.K.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho
 

Re: Generator problem???

Reply #5 –
First, camping at the Circuit of the Americas - pretty bad for us that were working: dry camping, sloping parking area, and VERY dusty roads.  The good camping had hook ups, paved parking and bordered the track - cost $2,000 for the weekend and I don't think tickets were included in that price!

I can see there is confusion over what is going on by the replies I have gotten so let me try again.

1.  I originally had two separate problems with the generator, the first was that the generator would stop when I released the stop switch and the problem was intermittent.  I would clean connections, it would work and then the next time I checked it  would go back to the same problem.  The answer turned out to be faulty connections with the voltage regulator which I replaced.  The second problem was probably caused by my constant attempts to keep the generator working.  The slip rings carboned up and I had no contact with the brushes.  Cleaning the slip rings solved that problem.

2.  In the past I have had the house battery not seem to last as long as it should because we normally camped in a RV park and were hooked up to shore power.  I was told in another post that the ferro-resonant battery charger in the compartment where the sewer hose hooks up was the cause of the early battery failures.  Not having the money to spend on a fancy triple stage charger, I just unplugged it.  In the process of reading about the Emerald control functions on page A-4 of the service manual I saw that the control board "B+ charge current from P1-6 flows to the battery."  And I thought that the generator would recharge the battery.  What I missed was the sentence that followed, "R6 on ground side limits charging current to 1 amp maximum." 

Having read that sentence I now realize that the generator is even less capable of recharging the battery than my 20 watt solar panel.  Because of cost concerns I will get a TriMetric 2025-RV battery monitor and disconnect the ferro-resonant charger once it recharges the battery.  Since I have a Tik-L Start it will keep the motor battery charged also.
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP