New to us '05 Interstate issues
 

Hello to all,
After having an 06 T1N 118" for a while, we decided to purchase a T1N based RV. We recently (yesterday) bought a 05 Airstream Interstate, 78K miles, very good shape. My more than capable wife flew to MD from CO and picked the rig up. All went well until early today when the battery light on the dash illuminated. It became apparent that for some reason the van battery was not charging. She made it to Charlottsville, VA. It is going into a local shop that works on Sprinters to have the charging issue diagnosed.
I have come to discover that the generator does not seem to charge the van battery due to the battery isolator. I had hoped that by running the generator while driving, it would charge the house and chassis battery to allow the rig to be driven despite a non-functioning engine driven charging system. Am I correct regarding the assumption that the generator will not charge the chassis battery thru the inverter/charger?
Secondly, the generator will not stay running while the van is going down the road. LP tank is full, the unit starts up while the rig is stationary, but dies when under way. Is this common or normal?
I'm a mechanic by trade, but I'm in Colorado and the rig/wife is in VA, so I can only go by what I'm being told.
Any and all input is greatly appreciated.

Doug In Gunnison
'05 Airstream Interstate 22FS

The battery isolator— if it's working properly— connects both systems for charging, as long as both systems have approximately the same state of charge. If one system is well-charged and the other is discharged, the isolator does its thing to make sure the low system doesn't drag down the charged system.

That's been my experience. Engine alternator will charge both systems while driving, generator will only charge the house system. Other owners may have different experiences; this seems to be one area where systems have changed from one model year to another.

That's kind of weird. I personally don't use the generator while underway, but other owners do, with no problems. If you have enough power to start the generator, you also have enough power to keep the propane solenoid switch open. Plus propane feed isn't terribly sensitive to bumps and jolts while driving.

My best guess is that it's low on oil. The Cummins/Onan generators have a cutout that prevents the generator from running if the oil is too low. While you're sitting still, there's barely enough oil to allow it to run, but underway, sloshing of the oil causes the "low oil" sensor to activate and shut off the generator. But that's only a guess.

Fixed...partially
 

Got a new/reman 120A alternator installed and all is fine. Under 500 bucks including labor, seems very reasonable.
Generator ran for about 40 mins yesterday with A/C on and had no issues, stationary. I'll check/change oil when she gets the rig home.
Thanks for the views and info.

So just for my info, how and where does one check the oil in the generator? Looks like it's tucked up underneath pretty tightly with no external access hatch.

You may have to lower the spare tire to open the access hatch.

I had the oil changed at 50K miles/40 hours on my 05 AS Sprinter, by my Sprinter dealer mechanic. He said the oil was full and the oil didn't look like it have worked very hard. He had to lower the generator to get access for oil service.

Ours is underneath, too, and we have it serviced by an Onan dealer. Not so handy, that part. :huh:

Just for general information, there is an on/off switch under there, too, which Doug located when the inside switch went bad.

Welcome to the world of Interstate ownership! The only way to go, in our opinion. :blush:


Maggie

To check the generator oil, I backed my to the end of the driveway so that the Onan access was over the gutter. Gave me enuf room to slide under and open the access door w/o dropping the spare. But may be different on an earlier model.

I am not thin and I can slide under there to check it on level ground, though there is not much room for maneuvering. There is an access hatch the comes of (assuming your unit is the same as my 2012 model) by lifting two tabs. Getting oil in is a bit of chore, I use a turkey baster to put it in one once at a time. Mine did exactly what you are describing for the reason that Protag mentioned. I had very high oil consumption at first, but now that it has some hours on it it's not bad, though I do still have to add some between changes.

generator
 

Thanks for all the replies.
While we chose the Airstream unit over other manufacturers because we liked many of the design features, this seems to be a place that they dropped the ball at some level. I know they probably thought with the low oil shutdown feature, manually checking the oil was not a real issue. I personally like a more "hands on" approach to maintenance.
As an aside, I have personally worked on about 5 Onan Microlites in class B units of various manufacturers with no start or start die issues over the past few years. Seems like these units are a little finicky. We have a Honda EV4010 in our bus conversion that has never so much as hiccuped. Maybe just an isolated situation, but seems like there is a fair amount of internet discussion about Microlite issues.

I don't think it's a case of them dropping the ball. Given the geometry of a Sprinter, the 2.5kW Onan seems to be the most generator that will fit in the space available, without extending too far downwards. Even at that, they had to replace the stock hinged Sprinter spare tire bracket with a crank-down bracket, because otherwise the stock hinged bracket would have obstructed the access door even when the tire was removed.

I agree that the space limitations are restrictive, and perhaps Airstream had few choices. Maybe it's Onan that should consider a remote dipstick kit for applications like this. Maybe I can craft one and use my Sprinter transmission dipstick. That would give me PLENTY of length for checking it in just about anywhere but the drivers seat!:lol:

The posters spare tire may be inside the rear doors. Access to the gen is easier if the rear wheels are on ramps. When I had mine the dealer had to replace the original gen, seemed to be pretty easy to drop it down. As a final note, my gen never worked properly, one of the reason I sold the unit. It would not stay running and service people could not find the problem. Hope you can figure out your problem, mine was a new unit with not many in service at that time. I am sure the service people are more familiar with the Interatate in general and the gen in particular. Jim

You guys really need to understand that the 2002-2006 is much different than 2007 onward in terms of AS's conversion design.

Well, all of the Interstate owner's manuals are available for download from the Airstream web page, so it's not too terribly difficult to look up the differences. Appreciate you pointing it out; I had forgotten.

The 2004~2005 manuals specifically state that the spare tire has been moved from underneath to inside.

The 2006~2007 manuals say the spare tire has been relocated on rear bath models, but not on mid-bath models.

From 2008 on, the Sprinter hinged spare tire bracket is replaced by the crank-down bracket.

Our spare is mounted inside the back door. We do, however have a trailer hitch on the back, which has, in my previous Sprinter experience, made access to the undermount spare more difficult. I imagine it will also make generator access more challenging.
I'm hoping that the rig will fit on the lift in my shop and make generator service a non-issue. Like others have said, worse case scenario, it can go on ramps or I can just dig a ditch with the backhoe and have the wife back the rig over me...:eek:

If the generator is using a measurable amount of oil in the 25 hr change cycle, then there's a problem somewhere. I check my about half way thru the cycle and if it's OK, then don't check again.

FYI, if the battery is dead, the generator will shut down. That's probably why it wouldn't stay running.

If the house batteries are too depleted, the generator won't even start. But once the generator is running the house batteries will charge. A mounted Onan generator is no different from a freestanding Honda or Yamaha generator in that regard; once it's running, you don't need to keep feeding it battery power to keep it running. But you do need to keep feeding it air, fuel, and oil in sufficient quantities.

In my B190, I did have to keep feeding it 12 volt power, or it would shut down.

Relatively easy test: Fire up the gen, turn off the converter, then disconnect your 12 volt battery. In mine, the generator would shut off. I discovered this when I was doing something unusual (I forget exactly what), and I was a bit surprised when the generator shut down, but after I thought about it, I realized that's how it's probably controlled (i.e., the off switch just cuts 12 volt power to it for a moment).

So, if theirs is wired the same way, since the alt wasn't working, as the batteries depleted, eventually the voltage would get low enough that the gen would think it was being shut down, and shut down. Then it wouldn't start again because the voltage was low.

Hadn't considered that. If the generator isn't actually generating power, it can't self-power either, and so will draw power from the batteries to keep the spark plug sparking. Once the batteries get too low, the spark plug quits sparking, and the generator shuts down. By the time the batteries are too low to power the ignition coil, they're too low to power the electric starter motor, too.

But for the same thing to happen to a properly-working generator, that almost has to be keyed to the throttle control. A generator throttles up to increase RPMs as the load on the electrical system increases. Whatever mechanism controls the throttle probably relies upon battery power, so if there's not enough battery power, you can bog down the engine by overloading it; RPMs don't increase as they're supposed to with added load, which causes the generator to shut down.

Still grasping at straws here, but haven't reached the last straw yet.

The generator probably WAS generating power. It was generating 120 volts AC. But that doesn't do any good for the 12 volt DC side if the converter is off. Then the alt goes, and suddenly the only source of 12 volt DC power is the battery, which will run down without anything charging it.

Home and fixed
 

The rig made it home the rest of the trip without incident. The reman alternator solved the charging issue and is working like a champ. I think I posted it earlier, but that entire fix came in under 500 bucks, more than fair.
The genset issue did turn out to be slightly low oil. Went ahead and changed it and topped it off, no more issue.
So far, we really like the rig. The 2 couches fits our use better than a dinette set up and the rear kitchen is plenty big enough for us and with the rear door open, it makes for a nice view.
Thanks for all the help, comments and suggestions.

reddog,you might look into one of the screen enclosures for your rear door, if you don't have one already.

Available from the Sprinter store, they are wonderful for parks, beaches, etc., where you have a beautiful view but insects keep your doors closed. :sad:


Maggie

1. A generator "throttles up" to maintain RPMs not to increase them. The purpose of the governor is to maintain 60 Hz output under varying loads. This means that RPMs have to be controlled within a fairly narrow range, roughly 59-61 Hz.
2. The governor on these and most generators is mechanical and does not depend on battery power.

Thank you. As slow as I type, my fingers still go faster than my brain.