Newbie question re: generator

daveseer · 07-09-2024, 04:30 PM

I just purchased a 2006 Sightseer, haven't even picked it up yet. When I was looking at it, the generator would start and run, but whenever I turned the ignition off, the generator would eventually die. The seller didn't know much about it. I'm not sure if the Aux switch was on or off, but I'm assuming if the switch is off that it couldn't connect/charge the house batteries and that's why the generator shut off. Is this a good assumption? I didn't have much time to diagnose the problem and it was raining to boot. Figured since the generator started easily and ran smooth that it should be an easy fix.

**Eagle5** · 07-09-2024, 04:49 PM

Greetings daveseer,
This is a wild theory, but the fuel pickup for generators is at the ¼ tank level. If the fuel level is pretty-much at a ¼ tank, perhaps the vibration of the V-10 engine was sufficient to splash fuel into the generator pickup line.
It is a good sign that it runs.
Welcome to the forum.
Eagle5

dkoldman · 07-09-2024, 06:01 PM

I have an even wilder guess...

Does it have a AGS system? It is possible if it does that the wiring is faulty. i.e if you have AGS in Auto mode and you turn the ignition off or on, it will shut down as part of safety. I assume you don't have it in AUTO even if you did have AGS but if the wiring is faulty, it may not know.

**creativepart** · 07-09-2024, 10:06 PM

Quote:

Originally Posted by daveseer

I'm not sure if the Aux switch was on or off, but I'm assuming if the switch is off that it couldn't connect/charge the house batteries and that's why the generator shut off. Is this a good assumption?

That sounds plausible.

How about this? Perhaps the house batteries are shot and can’t hold a charge. When the engine is running there’s 12v available from the alternator but with weak house batteries turning off the engine removes power from the Onan control panel killing the generator.

Like you need 12v to power your thermostat for your A/Cs to run, I’d bet the generator control panel is the same.

I like the fuel quantity idea too, but doubt it would restart after it ran out of fuel initially.

daveseer · 07-09-2024, 10:30 PM

It was on 1/4 tank. I thought about the cutoff but figured it wouldn’t restart so easy. Batteries are another option. AC was lit up but wouldn’t blow. I’m sure it’s related. Doesn’t sound too hard to isolate and fix. Thanks

Morich · 07-10-2024, 07:16 AM

I would assume the generator is not putting out AC power when the Air doesn't blow. If the generator is not putting out AC power, there will be no Dc from the converter, but as long as the chassis battery is connected to the coach, the generator has the DC control power it needs. Turn the RV egnine off, do power to the generator control is losst and it shuts down?
But you have not given us the basic info on which RV model to actually look at drawings of the power to verify that theory!

Some questions may help? Does the genset crank when the RV engine is not running? That would tell if the coach battery disconnect is on and the coach battery has enough charge to crank it?

daveseer · 07-10-2024, 07:20 AM

The model is a 2006 Sightseer 30B. No, the generator doesn't crank when the motor isn't running. Sounds like either the coach power switch is off or the batteries are shot. I pick up this weekend and these will be easy to test.

Morich · 07-10-2024, 07:46 AM

But a general thought might be that the coach batteries are dead as well as the geenrator not getting power to the converter and that providing Dc to keep it running.

I believe the coach battery disconnect will be closed to get the genset to crank. The DC power comes from the chassis alternator when the RV engine runs, allowing the genset to start and run. When the RV engine stops, there is no longer DC for it and it stops.

I would suspect several things?
One is bad coach batteries that won't hold a charge but more likely a problem with the wiring from the generator to the converter and on to charge those batteries. Bad batteries after being stored is common on RV as well as corrosion on things like battery cables.
Possible the breaker directly on the generator but I feel less likely than corrosion.

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Engine runs, there is DC power to generato as green line. but no DC from genset to converter on to batteries to maintain DC. When engine stops, DC is not comming from coach batteries nor engine as the mode solenoid opens.
Maybe as simple as corroded batterycable at some point between generator and converter but more likely at the coach batteries where there is a lot from battery fumes?

By no DC out, I mean it may be coming out of the converter but not getting to the battery!

Morich · 07-10-2024, 08:04 AM

Drawn in a different form from the correct drawing!
Engine running, solenoid is closed, power from it gets to gen. starter, etc. to make it run. The disconnect has to be closed to let that happen.
At that point DC power is good to gen. but when the RV engine stops, Dc power to gen. should still be there but coming from the DC made by the converter and also to the coach batteries. It should continue to run after the RV stops!

But since it dies, I assume the solenoid drops power from chassis but there is no DC power getting from converter to batteries and on to gen!
If the positive cable at the coach batteries is corroded that would be a common problem if RV has set for a time!

Click this snip for better view!

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**creativepart** · 07-10-2024, 10:02 AM

Picking up any "new to you" motorhome with some age on it, even if the mileage is very low, is to check the DOT manufacturing dates on all 6-tires. Generally, folks advise to replace them if they are between 5 and 7 years since manufacture regardless of mileage. And then the condition of house and chassis batteries.

Add to this list the roof/side drip rail interface. You may not be aware, but if the sealant holding the one huge sheet of FRP roof material has deteriorated then the roof can pop out of the drip rails and... sad to say can blow off in the wind as you drive.

It's pretty easy to check and can be a DIY fix but if you are not aware of it then you could be in for a major hassle and major expense, as well.

https://www.youtube.com/watch?v=jDd3NrdWSQA

daveseer · 07-10-2024, 01:37 PM

Thanks for all the good feedback. Lots of things to check out.

As for maintenance, has 6 brand new tires and the roof was just resealed and looks new. I'm a semi-retired jack-of-all-trades/master of none so I figure this thing will keep me somewhat busy and hopefully not somewhat broke.

**creativepart** · 07-10-2024, 01:45 PM

Quote:

Originally Posted by daveseer

As for maintenance, has 6 brand new tires and the roof was just resealed and looks new.

That's great. Some folks call resealing the roof different than the problem and fix in that video above. They reseal around vents and fans, and maybe the front and rear caps. But that's not the same as having the drip rail reseal shown in the video above. So, make sure you and the seller are on the same page about that.