Hopefully someone can add some ideas. Onan 2800 microlite starts but immediately stalls and the 12 volt main circuit breaker trips, so all 12 volt is dead. There is no load on the generator when this happens. Circuit breaker resets, all 12 volt restored until attempt to start generator and then the same things happen again. All 12 volt works on battery an when plugged into 120 volt.Any ideas??????

12v main circuit breaker ?you have 12v power, until you start the generator ?then this 'breaker' trips and everything goes black ?are you on shore power ? how are the batteries chargedyes .. there is a load, the converter will come on as soon as the timer on the ATS kicks in, also possible is any switch that might accidentally be on, like water heater or fridgea bad converter or two many items in the on position, will cause a small generator to stall, 2800 is NOT a large generator

MrWizard wrote:12v main circuit breaker ?you have 12v power, until you start the generator ?then this 'breaker' trips and everything goes black ?are you on shore power ? how are the batteries chargedyes .. there is a load, the converter will come on as soon as the timer on the ATS kicks in, also possible is any switch that might accidentally be on, like water heater or fridgea bad converter or two many items in the on position, will cause a small generator to stall, 2800 is NOT a large generatorThank you for your thoughts. The inverter is in the "off" position so no instant load there. Refrigerator and water heater in off position. Microwave off as well. Water pump off. Air conditioner also off. What else is there? Yes, it is a small generator and I only run one load at a time. Not on shore power at the time. Yes, everything goes black, then a automatic resetting circuit breaker (I assume) cuts all 12 volt off. After about 5 minutes, 12 volt returns.

sounds like to me it might be shorted cells in the battery bank... But you say when on shore power both AC side and DC side (with batteries connected) works ok. Only happens when you start up the generator which switches the shore power transfer switch and selects generator to run the AC Distribution Panel.Something not adding up here. The shore power and the generator feeds the same point depending on which position the transfer switch is in...Keep in mind both the converter/charger DC output and the 12VDC coming from the batteries both feed the same point on the 12V Distribution Center... The 12VDC circuit breaker is only on the battery side...Sounds like a big load is causing the the generator to trip out...The only MAIN 12VDC Circuit Breaker I can think of is in-line between the battery and the 12V Distribution Panel mounted close to the battery terminals. Its purpose is to protect the wiring in case a cable short to frame ground.This is a very simplified block diagram of the 30A AC and DC Power Distribution in a regular trailer setup... Might give you a clue...Roy Ken

I think the Onan generators need 12V to generate power, though typically I wouldn't think they'd be wired through the main house 12V disconnect as the generator starter motor takes a pretty large current.If the batteries are low and the converter is a large unit and the wiring is low impedance, possibly the converter is trying to output more current than the 12V self-resetting circuit breaker is rated for. Possibly the circuit breaker is malfunctioning and kicking out at too low of a current. It would be helpful to locate it and see what the currents are (and what direction they are flowing) when the 12V supply goes dead.It may also be that there's a fault in the generator circuitry. While a 120V overload could stall the generator, I don't see how that same overload could normally cause the 12V system to shut down unless there was also some other fault.

When operating the 12v just on the convertor (batteries switched off to avoid overcharging by the old style fixed rate charger) I can try starting the generator and it tries to crank but there isn't enough power to start it. That may be the condition causing your rig to trip the breaker. If I switch the fully charged batteries on, I can crank the generator with no problem even when it takes awhile to start.

Generator stalls & main 12 volt circuit breaker trips

pianotuna
Nomad III
Mar 24, 2016
Great Job!

joebedford wrote:
This is what the primary DC distribution looks like in my RV battery compartment.
MEXICOWANDERER
Explorer
Mar 23, 2016

http://www.ebay.com.au/itm/80A-Car-Stereo-Audio-Circuit-Breaker-Amplifier-Amp-12V-24V-/321933991037

Try this for a main breaker. I have found they have 99% fewer problems over a 5 year span. Locate it several feet away from the battery positive post.
DownTheAvenue
Explorer
Mar 23, 2016
Thank you everyone for your help. I am leaning towards defective main, resetting circuit breaker. I will post the solution if and when I have it!
DrewE
Explorer II
Mar 22, 2016
joebedford wrote:
This is what the primary DC distribution looks like in my RV battery compartment. The battery is connected to the bus bar on the bottom. The heavy DC loads (like front jacks) are connected to that bus through auto-reset breakers.

May I suggest replacing that plastic circuit breaker holder with this style available here:

The plastic ones have the very bad characteristic of insulating one terminal on the breaker, forcing the current to flow through the threads from the nut to the stud. This can be trouble-prone. The metal one allows the connectors on both terminals to properly seat against the shoulder of the stud on the breaker. I had a similar setup on my motorhome, and found some of the breakers were barely sound structurally (partly from age but I think partly from the heat/connection issues). The metal bracket is a bit wider and I think a hair taller; the spacing of the breakers is the same, but the mounting ears spread out a bit more.
joebedford
Nomad II
Mar 22, 2016
This is what the primary DC distribution looks like in my RV battery compartment. The battery is connected to the bus bar on the bottom. The heavy DC loads (like front jacks) are connected to that bus through auto-reset breakers.
MEXICOWANDERER
Explorer
Mar 22, 2016
Battery power to be interrupted by an incoming charge would have to involve a DC transfer switch
A gen auto start has such protection but an RV? "All DC power is chopped. What does the chopping? A psychotic converter that has the ability to sever power can do it but newer converters are power supplies - battery chargers. Is there a master breaker inside the rig's fuse load center? Something that goes open circuit causing a general outage including generator control? Surely they wouldn't hide a trashcan grade sixty-nine-cent auto reset master breaker inside a fuse load center, would they?
Matt_Colie
Explorer II
Mar 22, 2016
I think YXM is on track, I saw this happening on a yawl a few years ago. The APU would start and promptly shut down and everything was dead.

It took some doing to find, but the final diagnosis was that the house bank was asking too much of the cold generator. Modern converter/charger/inverters can hit the AC supply hard when first fired up. We finally trapped the sequence:
1 - The generator (APU) would start (autostart in this case)
2 - The converter would grab the output and lug the poor APU down and at the same time is would pop the DC breaker at the system main and if it didn't it would pop the AC breaker on the APU. The the converter would pop the battery main breaker.
3 - It would be suddenly quiet and it took less than a second for this to happen.

We were able to get the owner going again by having him shut off the autostart and open the APU breaker. Then, fire the APU and let it get rolling unloaded. Close the APU breaker and cross fingers.
If it stayed on line great.
If no, disable the convert/charger/inverter monstrosity and get the APU stable - this gave the house bank time to recover from the starting load of the APU and then when the converter was enabled, it didn't pull the APU to its knees.

More fun on the water.

Matt
DownTheAvenue
Explorer
Mar 21, 2016
MEXICOWANDERER wrote:
Try to insert an image into this thread showing the "12 Volt Circuit Breaker. Curiosity overwhelms me...

I have no idea where it is, I just know what happens.
MEXICOWANDERER
Explorer
Mar 21, 2016
Try to insert an image into this thread showing the "12 Volt Circuit Breaker. Curiosity overwhelms me...
DownTheAvenue
Explorer
Mar 21, 2016
wa8yxm wrote:
I can tell you why the generator stalls. but not why the breaker is breakering.

The generator uses 12 volt BATTERY/CONVERTER power for the fuel pump and for ignition control.. So if it looses the 12 volt feed due to the main breaker tripping, It's the same as pressing the OFF button. or turning off the ignition on your car.. It does not "Stall" it is "Shut Off".

But I have no idea why the breaker is breakering.. Possible converter issue. that is the only thing I can think of, is a converter issue.

This helps to explain why the generator quits. I assumed it stalled. It is in a class B van AKA "motorhome".
Thanks!