Confused about Inverter/Shore Power

[Stan Simpson]

I have our coach plugged in to a 20 amp outdoor receptacle when we are not traveling. It keeps the house batteries charged. When I look at the Xantrex Inverter panel above the door, I have Invrtr/Chrgr selected, and there is a green light at the top of the panel. It always shows on "float" indicated by a floating X on the screen.

Today, we went to the coach to do some cleaning to get ready for our trip. As soon as we arrived, I turned on the Genset so we could use the AC. When we tried to put the slides out, they would barely move. I looked at the Aladdin and it said GenSet Power selected with 119 on one leg, and 121 on the other leg. When I pushed the switch to move the slide, the GenSet surged, the Xantrex screen went off, and the slide wouldn't move. I tried it on all of them. A few seconds later, the Aladdin screen said Open Ground. Then in just a short while, that went away, the Xantrex screen came back on and the screen showed a graphic regarding "bulk charge", until I hit a slide out switch again, and it went blank, again. 

I turned the GenSet off, the transfer switch put the coach on shore power, and it was so indicated on the Aladdin. Without the generator running, I could move the slides in and out at will. The Xantrex screen had the green light at the top, and in a few minutes it went to float.

I am clueless. How are the slides operating flawlessly on 20 amp, and won't operate with 50 amp from the Genset? Does any one have an idea?

Thanks,

Stan

[Jerry Emert]

Stan, I would look at the transfer switch generator side relay.  Might be some burned/corroded contacts.
Jerry

[Stan Simpson]

Stan, I would look at the transfer switch generator side relay.  Might be some burned/corroded contacts.
Jerry

Thank you, Jerry. I'm going to the coach today, and will take pictures of the bay that holds my power cord, transfer switch (I think) and surge protector. Perhaps you can look at them and let me know where the contacts are? Or are you talking about one of those relays in the electrical bay?

Stan

[Edward Buker]

Stan,

This indeed is a puzzling one.... It looked to me like for some reason while on the generator you had an excessive current load when you hit the slide button, that caused the generator to surge in response and the voltage drops gave the Alladin some odd voltage input that it interpreted the best it could.

I do not know if your slides are driven by 12V and use a hydraulic pump or not. If it were me I would put the generator under some load like the two roof airs and if that went well then repeat the operation of moving the slides while on generator power to determine if this was a one time chance issue related to the slide drive system that could have happened while on shore supply but by chance did not.

There is a chance that the slide had some mechanical locking issue or a 12V motor issue (given it is a 12V hydraulic drive) that some how cleared itself. While it could be a contactor issue at the transfer switch, I am more in the camp that a heavy electrical load for some unknown reason created the issue and the generator surge response.

Later Ed

[Stan Simpson]

Ed,
I went to the coach today. In sequence here are pics of my Inverter/Charger and the Aladdin.

1. When I arrived at the coach. Nothing on, 120 volt plugged in to 20 amp receptacle. Before doing anything else, I put both LR slides out, using 12V power only.
2. Turned the generator on and let it run for 15 minutes. Picture is the Inverter/Charger showing GenSet turned on manually.

3. Turned on LR AC and the 120 ceiling light in the galley. Aladdin shows drawing 11 amps. AC and GenSet running fine, cooling as it should.

4. Attempted to extend a slide-out. Generator surged, Aladdin shut off. AC shut off, and the ceiling light went off. Slide-out would barely move an inch. And the Xantrax screen went totally blank and then showed this. (light at the top is off) The GenSet did not shut off.

5. Shut everything off, including the GenSet. Transfer switch put me back on shore power. Turned the GenSet on, and then the AC and ceiling light. Picture of the Aladdin after that. Same as before I tried to move the slide.

Before I left the coach, I moved the slides out and in, using only the house batteries and the 20 amp shore power.

Thanks,

Stan

[Edward Buker]

Stan,

One thing I noticed is the solar indicated 24V in one photo and 15V which is more inline with what might be expected in another. I am wondering if that high voltage solar condition is somehow triggering things to shut down. Has your screens always showed this kind of solar voltage variation and is that higher voltage occurring just when the genset is running?

One other test is to have both airs running with the genset given one leg has no load on your monitor screen. It is possible that the no load leg is the leg the inverter charger is on so it was not really tested with another load to see how the generator responded.

From your test it is clear that he genset is operating normally with the load on one leg that you put on it. If with the two air load the genset runs fine then it is also clear that moving the slides with the generator on is triggering some cascading repeatable effect that is shutting things down which I am afraid is some kind of overcurrent (shorting) condition or some kind of generator AC waveform change that the inverter charger cannot handle causing it to pull a lot of AC current. 

The second test would be to turn off the inverter charger with the generator on supplying AC and see if the slide runs properly. That would tell you that this is strictly an interaction between the genset and the inverter and not actually any slide drive issue drawing excessive current.

You did not mention what voltage and what type of drive mechanism your slide uses. Also do you know if you have an electronic inverter type generator or a standard generator that supplies the AC?

One last possibility, there may be a setting on your Xantrex inverter charger where the 13V charge current could be set to a lower value to see if that eliminates the event. Not sure what the options are but if you can limit the inverter charge current to 50 amps as a test, while using the genset, and see what running the slide does. If that works it may provide a work around and some insight.

Later Ed

[Jerry Emert]

Ed is far more experienced than I am so I would follow his advice.  Another thought because I'm a little simple minded.  The transfer switch (TS) itself is the only difference between the shore power and genny power in the 120AC power circuit in the coach.  On one side shore power and/or generator power enter the TS.  On the other side (maybe top and bottom) the 120VAC goes out to the coach.  The coach doesn't care if it is coming from the gen or shore pedestal.  Most coaches with an automatic TS default to generator power if shore and gen power are both active at the same time.  Since your issue seems to be on gen power only, my Navy trouble shooting training tells me to start there.  Since the TS switch is the first place that is different, working backwards, that is where I would start.  I would unplug from any kind of shore power, start the genny and check the output of the TS, both 120VAC legs.  Then go from there.  If both 120 legs are good, you still may have a loose or corroded connection that will not pass the required amount of current to move your slides.  I don't know what that current is.  My coach has 3 electric slides and I just recently found out that if we try to operate two slides at once, only one will function.  As soon as the one is completely in or out the other will start to move.  Once you open the TS, make sure no power, genny or shore, is on and make sure all connections are tight in the TS.
Good luck and remember I'm not an expert. 
Jerry

[Edward Buker]

Jerry,

I think you are using good logic from your experience and many times contacts are the issue causing erratic operation. In this case, I think if Stan can run the two roof airs, which are motor loads with high starting current using just the genset and the transfer switch contacts then that should rule out the transfer switch contactor issue as a source.

The slide 12V slide motor should represent a lighter load given the battery bank is also available as a DC power source then the 120V compressor motor starting load. I may end up with egg on my face but that is my logic here.... This is a strange one where I think the Xantrex becomes a load, pulling excessive current when the slide is activated, not sure why yet.

Later Ed

[Gerald Farris]

Stan, Jerry, and Ed,
What are the chances that the movement of the slide is shorting the wire that is carrying power from the generator?

Gerald

[Jerry Emert]

Another thought that comes to mind?  Will the slides operate on battery power alone?  Mine do.  I don't like to do it because I perceive it as a significant drain on my batteries so I always  hook or stay hooked to shore power when I extend or retract my slides.  I still would rule out the TS before I spent a lot of time looking for other things.  In my experience you can go nuts looking for things that don't exist and wind up right back where all it takes is a couple of readings on a VOM to be sure.  It may be a short in the slide as Gerald suggested or a corroded connection at the generator itself on one leg.  Or the way these beasts are it could be a corroded tail light wire!  Just kidding about the tail light wire...I think!!

[Edward Buker]

Gerald, Jerry,

Gerald, good thought...The genset wire or a wire nut connector shorting when the slide moves is possible and could explain the heavy load just with movement and just using the genset. Stan could visual the wire ad see if it got pinched. On the generator end there is a coupling block with screw terminals under a cover on the top of the generator. On the other wire end there is a covered box in the back right of the bay where the generator connections are made. You could confirm that the wire connections are tight and corrosion free. On the generator end do not over tighten, there are lug screws in an aluminum block that could strip, just confirm they are tight and the wire is seated in the opening using a mirror and light....I am describing my own installation Stan, yours may be similar. You may or may now want to "get dirty" here, never know how far a person wants to get into these things....

Jerry, I was confirming the contactor quality of the TS with a more severe load test then the slide represents but there is more than one way to skin a cat, nothing wrong with Stan breaking out the meter if he prefers. You are right, one way or another there is a need to verify that the contacts in the TS are not the issue.

Later Ed

[Stan Simpson]

Lots of stuff here to disseminate. I will go to the coach this afternoon and try some of the suggestions here, and report what I find. I'm no electrician, and although I have a VOM, the readings are Greek to me. Might be time to bring in "Bob the Electrician", who has helped me out many times.

[Jerry Emert]

If you are not comfortable around electricity then it sounds to me that you have a good plan!  Call Bob!  120 at 50 or so amps would definitely ruin your day.  All it takes is one mistake and you can do serious damage to the coach and more importantly, YOU!!
Good luck
Jerry

[Stan Simpson]

Here are the results from today.

With genset off, and no shore power plugged in, the slides moved in and out with no problem. 1st picture

With genset and both AC running (see 2nd picture) activating the slide caused 1) the inverter to shut off 2) the AC (both) to shut off 3) the Aladdin to shut off 4) genset remained running. The slide out moved about half way out before grinding to a halt.

After turning off both AC, the inverter and the Aladdin came back on. The Aladdin showed this screen immediately after I activated the slide. (picture 3) The voltage on the Solar charger also spiked. I turned off the genset, and the slide moved back in with just battery power. 

I turned off the inverter/charger and had  only the genset on. No AC running. Again, as soon as I activated the slide, the Aladdin shut off, and the slide would barely move. I turned the genset off, turned the inverter/charger back on, and the slide moved, but very slow. I plugged back in to shore power, and got the same Open Ground error message on the Aladdin, and then after a few seconds, the shore power connected. The slides moved fine after that, without the genset on.

Two times, while I was cycling between the genset and the shore power, when turning the generator back on, the Aladdin would show 'Power Delay Active' then this screen (picture 4) would come on for a few seconds before showing, 'GenSet Power Selected'. Notice the 60 amps. The AC was not running. Notice the spike in Solar Charge voltage. Picture 5 shows the inverter/charger status when I left the coach.

[Steve Huber]

Stan,
It almost has to be that the slide movement is causing a connection to fail in the generator cable/connections as Gerald suggested. The slide motors get their 12v power via the inverter. If wired like my 07, power for front (hydraulic) and rear (electric) slide motors is supplied by a single wire each. The slide circuit doesn't see or care if the 12v is generated via batteries, shore/inverter or generator/inverter. Since your problem doesn't happen when on batteries and everything seems to run on generator power except the slides, it seems to follow that the slide movement is causing the problem.

Some questions to help better understand this;
1.   Does problem occur when moving any slide or just one or 2? Which ones?
2.   Once the problem has occurred, (eg trying to extend slide), have you turned off the generator and extended the slide completely and then restarted generator? Does it run and power ACs, etc? If so, have you tried retracting slides with the generator running? Does the problem occur and if so, when (what is slide position)?

Steve