Inverter failure, Help

[Joel Ashley]

I just had mine repaired with two new boards for $935.  An invasive varmint had “polluted” atop it, and I goofed and tried to reset it while plugged into power.  If you can’t ferret this out, M&M RV Electronics told me they had 2 Magnum MS2012 rebuilds at $1100@.  Fred also had helped me determine that the 300amp fuse had blown in the battery bay fuse compartment.  It was the wrong fuse (from the factory!… should’ve been a slo-blo), but it didn’t save the boards.

Joel

[Scott Shearer]

Dennis,

Yes, if the inverter has 12-vdc suppled to it, then you should see something at the remote or on the LEDs at the inverter.

As Fred suggested, you should check the voltage from RED to WHITE and BLACK to WHITE to make sure that you don’t have an open neutral.

If you have 120 on each leg, I would try the following:
Turn the shore power off, have someone turn it back on while you monitor the Aladdin Coach Electrical Status screen. What does the status line read? Are there any error messages? The Surge Guard 40250 has the capability to report status and errors to the Aladdin system.

The status sequence should be:
NO AC POWER PRESENT
POWER DELAY ACTIVE
SHORE POWER SELECTED or if gen set is running, GEN-SET POWER SELECTED

If you have CLEAN 228VAC shore power at the transfer switch and the shore power contactor is not engaging and you don’t see any error messages on the Aladdin screen, I’d be suspicious of the transfer switch. There is a troubleshooting guide for the Surge Guard 40250 in coach assist.

-Scott

[Fred Brooks]

    Dennis,
I asked you the voltage between the red and the neutral and the black and the neutral to confirm both hots and the integrity of the neutral. If you have shore power into the surge guard and the relay is not engaging, you have a bad transfer switch. Fred

[Dennis Belfils]

Sorry Fred, I thought I modified my response, but it didn't post. Anyhow I have 116 & 118vac Black to white, red to white. Apparently the pedestal 50amp at this park is possibly the problem. The transfer switch doesn't like it, keeps opening & closing the contactor. Switched over to 30 amp, OK. Inverter still out though

[Joel Ashley]

Yes, as Fred and Scott and your own report suggest, it’s likely your 50amp post outlet has a bad Neutral.  I’ve run into them a couple of times in RV parks.  Management usually calls a local electrician to replace the outlet.  Your inverter may have suffered, but as a first easy check take a voltmeter to the 300amp ceramic fuse in the battery bay fuse box.  Put the black lead on a negative battery post and touch the red to either side of the fuse.  If there’s nothing on the left side, the fuse is shot.

Joel

Top photo: new slo-blo T300 Magnum fuse in place.
Bottom photo:  incorrect old factory fast-blo A3T300 fuse.

[Dennis Belfils]

New RV Park hooked up to 50amp for the last 3hrs, no problem. Still working on inverter. Appears our DC voltage is alittle different than what the schematic says it should be. I have 2 hots off the battery bank. One appears to go to one side of the 300amp fuse, & the other looks like it goes straight to the inverter. Will have to trace it out better when we get to Summer home. Thanx for all the input......

[Jerry Emert]

Dennis, I saw two things that caused me to have a question. First did you check the breaker on the inverter?  First time I had an inverter issue years ago I didn’t initially see the breaker on the side of the inverter because it’s mounted on the roof of the bay and the breaker was hidden by a lip on the mounting. It was on the left side bottom when looking from the front where the cables are. Second you mentioned that the inverter got power fro the main panel to the inverter sub panel. That’s not correct. It gets power from the main panel to the inverter. The 120 output of the inverter goes to the sub panel. Maybe I misunderstood. I just had a very similar problem, still do actually. I took the 120 output from the inverter and connected it to the 120 input to the inverter. That sent the 120 directly to the sub panel bypassing the inverter. My charger doesn’t work but I have a maintainer on the batteries so all is good while I wait on a board. Hope I didn’t confuse matters. Good luck.

[Dennis Belfils]

Yes it sounds like we have similar problems. I believe I stated that the inverter gets it's 120vac from the 50amp panel, thru a 30amp breaker, then thru the inverter that basically acts like a switch to use the power it gets or inverts via the batteries. From there it goes to the 30amp panel. I removed the 120 input/output wires at the inverter & wire nutted them together. I am now in the process of tracing the 12v wiring as our rig does not conform to the schematic. Schematic shows 1 wire from the +side of the battery bank to the 300amp fuse, then to the inverter. I have 2. The sequence of events have made this complicated. First battery failure, then inverter, then bad power at the park we arrived at, now even if I determine a bad inverter, none are to be had. Have ordered a battery maintainer to buy some time as you did. Thanx

[Joel Ashley]

So Dennis, the two positive 12v cables you reference… you have two fastened to the inverter + post, or to a junction nearby?

Mine has a large junction just aside the inverter with 2 red cables coming to it and 1 short loop to the inverter post.  I’m not sure where the second long cable goes.  It makes no sense to bypass a protective fuse, so I don’t expect it to be a direct link to the battery;  there must be another device involved that someone more knowledgeable than me can reveal.

Joel

[Steve Huber Co-Admin]

Dennis,Joel,
Look at pg 15 of the 2006 Monterey wiring diagrams; Main DC Distribution. It shows 1 3.0 awg wire coming off the house fuse. it then attaches to a terminal stud from which 2 3.0 awg wires lead to another terminal stud where it then drops to a single 3.0 awg wire to the inverter. I surmise the split to 2 wires is to prevent current loss over the lengthy run. I suspect that in your coach they simply brought the 2 wires from the first stud directly to the inverter.
Steve

[Joel Ashley]

Yeah, I’ve noticed that odd map feature in the diagram before, Steve, but assumed I was too uneducated in diagrams to decipher it and it went no further.  Thanks for the clarifying;  sounds like a reasonable explanation, although on this short coach it’s not particularly far from battery bank to inverter.  It may be just standard procedure install for all models.

😉Joel

[Dennis Belfils]

Thanx Steve, I agree with your assessment of the additional wiring due to distance. It's been abit too wet here where we are at to work outside for now. I can see the first terminal stud from the battery bay. It does seem to be odd that they put a 300amp fuse to protect the inverter and then bypass it. Will continue to trace it out when the weather breaks and let you know.