Onan Microquiet 4000 Generator - 1999 Tioga

Sorry so late. Home now and not connected to shore power.
Power cord of RV is now plugged into the outlet on the MH.

Ken
Bethlehem, Ga.

You can get an initial reading of the house battery voltage from any 12 v plug inside the house area such as by the TV, if it is easier. Or at the 12v fuse box. Or at a built in light fixture.

Jim

OK Gentlemen, I will plan to crawl underneath the MH tomorrow when it warms up a bit to check the 2 house battery connections/wires. It will be tomorrow evening before I can test the voltage on them when not connected to shore power. - (Still need that battery for my multimeter)

I will provide an update tomorrow evening after the little lady and I return home from our trip!

Ken

In my other post, I left off that the main thing to keep the genset ignition running is of course it's own 12 v output. If there is something wrong with that for some reason, other things like the Motorhome battery can ALSO provide 12v for the genset to keep going, and there are quite a few of them.

The strange thing is it shutting off when Motorhome engine is shut off, when the shore power was running the converter.

My experience is the same as yours gotsmart.

Jim

If my house battery is too weak to start my Onan MQ 4000, I start the MH's engine and then walk back to the test panel and start the genset. After the genset has settled down and is running smoothly (about 30 seconds) I turn off the MH's engine and the genset continues to run smoothly.

Yes I would plug into the outlet to let the genset provide the AC power to test. What is the voltage on the house battery with the rig disconnected from shore power? The Onan spec says it needs a 350 CCA battery, and the 12v converter puts out less than 100, so if the battery is dead the converter probably cannot start the genset even though it was connected to shore power, especially if a dead battery was sucking up its output.

How are the connections to the house battery and the wires into them?

It's what Mex said - the battery is not giving power to the genset for some reason.

Jim

Well, I have to apologize...I did not get the much needed battery for my voltmeter and did not check the 2 house batteries today.

I appreciate your post Jim. Question regarding your question:

I am connected to 120 right now. Should I unplug that and connect the C's power cord back into the "rig" before trying to start the generator?

Also, when I do not start the motorhome and try to start the generator from within the coach using the switch at the control panel, it just dims/flickers all the lights in the trailer and makes a slight humming noise but does not actually start. - (Keep in mind, I am still connected to 120V)

Ken

Yes. The Onan should run even with the house battery disconnected once it is started and with no connection to the engine.

My guess is either the Onan is not producing 12 volts, or something is pulling down the 12 v supply. It might even be as simple as bad grounds, and getting ground through the chassis engine circuits. When the Motorhome starts, the relay that is energized by the ignition wire is connecting the engine 12v system to the house battery to charge it. This is supplying the 12 v to keep the genset running right now.

Once the AC power from the genset turns on, and the converter in the house portion is turned on, will the Onan stay running? In my old C I could tell the AC had come on once the microwave display powered up and the genset RPMs dropped down for a moment.

There are basically 4 sources or 12 v available and really any ONE of them should keep the genset running, assuming it is a good source (not say a fully discharged battery): 1) the house battery, 2) the house AC to DC 12 v converter, 3) the alternator on the chassis engine and 4) the chassis battery.

So for example, without starting the Motorhome engine, I would expect that if you press the switch that joins the batteries, the Onan probably also runs.

Jim

What is weird is that the generator is running, so when I turn the vehicle off...shouldn't the generator continue to run on its own - (without the vehicles 12 volts) or does it need a continuous connection to a 12 volt power supply (house batteries)?

I will have to check the 2 marine style (house) batteries to ensure they are fully charged and then try to trace a line from them to the starter on the generator.

I will try to post my findings/pictures later on tonight.
Thanks for any further assistance/suggestions.

Ken

:-)

Something is interfering with the coach batteries delivering power to the Onan's starter motor. When you start the engine, the battery and alternator that keeps the vehicle charged and powered is traveling back to the Onan. When the engine is shut off the power stops. The Onan keeps running because it develops its own power. But when you shut it off, the coach circuit goes dead. Is this understandable?