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dallas121469 08-03-2021 08:38 PM

Need second opinion on possible bad inverter.
2007 Monaco Dynasty

Getting internal fault 1 after about 1 minute of inverter trying to run. Clicks a few times, appears to be charging per monitor station and volt meter check but eventually shuts down.

Have 120 on both legs of pedestal, have 120 on both legs in and out of transfer switch. Have 120 at breaker , 120 on both "hot ins" at inverter, both "hot outs" have 120 while the inverter is working.

With inverter off I get about 25 volts on the positive lead mounted to front of inverter. While inverter is trying to run it jumps up to maybe 40 on the positive lead.

The charging system has never been right as long as Ive owned this rig. Initially it was just chassis batteries that wouldn't charge but now neither bank charges.

Is this more likely a Big Boy issue or the inverter? Or even a relay?I have been meaning to replace the Big Boy ever since I discovered chassis batteries wouldn't charge but never got around to it.

Thanks in advance

Biljol 08-03-2021 11:01 PM

Ok easy I think the dc (battery’s) are wired wrong you should have 12v-14v not 25. I am surprised you have not had other issues.

Do a google search on battery’s parallel vs series.

K7JV 08-04-2021 08:57 AM

I've not dealt with fault codes on our inverter, so you would want to go to the manual for it and see exactly what fault code 1 is telling you.

Also, I'm a little unsure of some of your measurement locations. If you pulled the cover off of the transfer switch and read the voltages you should have seen three sets of connections. One is for the shore power input, one is for the on board generator and one is for the output to the shore power breaker panel. You should read 120 volts line to neutral (and ground, too) from the H1 and H2 terminals and you should read 240 volts from H1 to H2, assuming you are plugged into a 50 amp shore power source. You should read essentially zero volts on any of the terminals on the generator input. If that is all true, your transfer switch doing what it should.

The circuit from the transfer switch goes to the shore power breaker panel. There should be two 30 amp breakers that feed from that panel to the inverter. That is the AC source for your inverter powered loads and your battery charging circuitry. You should read 120 volts AC to neutral/ground on both of those breaker terminals. If so, you are good to the Magnum.

The Magnum inverter/charger has a transfer switch built into it that selects either power from the shore power panel or from the battery to power its loads. If shore power or generator power is there, it uses that to power all of the loads on the inverter breaker panel. If neither of those sources are available, it switches over and draws from the battery and inverts the 12 V DC to provide 120 V AC.

The DC terminals of your Magnum inverter/charger should be connected to the coach battery with that connection happening in your rear run panel. Just to the right of your Big Boy relay, you should see four breakers. They don't look like normal breakers, but that's what they should be. The bottom two are tied together and are from the Magnum. That is where the inverter/charger is tied to the coach battery. You should read 12 V DC from that main lug to ground.

Your 25 volt reading is very curious. But if you are reading a voltage on a point that is not solidly connected to a voltage source, many meters will display numbers that are incorrect. Also, when I say 12 V DC, that could be anywhere between 12 volts and 14.5 volts, depending on what is going on at the time with your charging system. When I say 120 V AC, that could be anywhere between about 114 volts and 126 volts, depending on what is going on with the electric utility's system or your on-board generator's voltage regulator.

Lastly, there is a lot of logic going on with the control of your Big Boy relay. It is controlled by a circuit board in your rear run panel. After you've been connected to shore power or your on-board generator for several minutes, set your meter to read DC and note the voltage between the two large lugs on the Big Boy. You should see a very low number. I would not be happy if it showed more than maybe 0.2 volts. That reading will tell you whether the Big Boy contacts are likely to be in trouble.

Finally, exercise extreme caution when pulling covers on your transfer switch or your breaker panels. If you're not familiar with those sorts of devices, please seek help from someone who is. But it sounds like you've already "been there, done that". Good luck. I am assuming (knowing the risks in that word) that your '07 is essentially similar to our '06 Dynasty that we just traded off. But if I can help further, please check back.

dallas121469 08-04-2021 09:52 AM

Thanks for the input. I'm pretty comfortable around electricity. I was going to check the battery bank to make sure they were hooked up correctly but ran out of time. I hooked them up in the spring just the way they were last year but that doesn't mean the guy before me hooked them up correctly.

I also forgot to mention that I have two breaker panels: a main and a sub. The main panel was reading fine on all breakers so power is getting there without any issues. The sub panel only has power when the inverter is working and the "hot outs" on the inverter only have power when the inverter is running.

I''ll check the manual today after work to see if it lists the fault that I mentioned and I'll check the big boy and breakers in the rear run panel.

Biljol 08-04-2021 10:35 AM

The two rear panels are correct one gets power from shore or genset the other from the inverter.

This keeps the large loads from pulling power from the inverter that can not handle them.

K7JV 08-05-2021 07:10 AM

Very good, "Dallas". I'm sorry I couldn't get back to you yesterday. I will add that I am pretty sure your batteries are not mis-connected. Had that been the case, you would have had massive problems long before now. So I'm pretty sure you are good, there.

You are right about those panels. And "Biljol's" summary is spot on. The one serves the loads that are able to be served only when connected to shore power or running your generator. That includes things like air conditioners, washer/dryers, etc., that would quickly "kill" a battery powered energy supply. It also serves the battery charging function for both your coach and your house batteries. And, it supplies power to the other panel when shore or generator power is available.

The other panel only serves those loads that can reasonably be handled by your coach (house) battery bank. That includes your lighting, your fans, your AC outlets, and such. It gets its power from your inverter.

When shore or generator power is available, your inverter routes it thru straight to the second panel. (I call it the inverter breaker panel). When shore or generator power is NOT available, it draws from the coach battery bank and inverts it to 120 VAC and sends that straight to the second panel.

Your manual's explanation of the fault code is the key, here. I look forward to hearing what it has to say. Hopefully your inverter is ok, but at this point it really does sound like everything else is working properly for you. Fingers crossed.

Biljol 08-05-2021 07:30 AM


I agree that the battery’s would have been giving him much more problems but how is he getting 25 volts on the battery cable lug on the inverter?

I would have assumed he would be getting a battery overvolt error on the inverter.

K7JV 08-05-2021 07:36 AM

I wonder if the indication on the meter might not have been mV rather than volts. Reading voltages on circuits that are "off" but in the presence of other circuits and systems will almost always have induced voltages on them, to some degree. Digital meters have such a high input impedance that they will actually "see" those voltages and provide a value where a "good old" analog meter would have shown a solid zero. It is my personal policy to disregard voltages taken from de-energized circuits, and if he had his battery disconnect open, that's what he would have been dealing with on the terminals of his inverter. It's really tough to say how everything was configured and exactly how he took the reading, but I'm guessing that the 25 volt thing was a false lead. Those sorts of things can really throw a troubleshooting project off track in a hurry.

dallas121469 08-09-2021 05:46 PM

Okay. So last week after my original post I went back to do some more troubleshooting and wouldn't ya know it everything seemed to be working normally but the inverter swas louder than in the past

Big Boy was showing about .4 to .6 volts, the breakers near the big boy all had high voltage readings, batteries seemed tobe charging, I was able to run both AC units for a couple hours etc. The batteries are 6 V in this rig and all were hooked up correctly.

My understanding is that batteries in series stack their voltages so why shouldn't I get a 25 volt reading on the battery charging lug with four 6 volt batteries?

Anyway I shut everything down and tonight went back out and everything is a mess again. Lights are flickering, batteries low voltage, inverter making noise, my auto antenna was going nuts, screen on the inverter monitor not working etc.

At this point I think the coach batteries are hashed from all the abuse because they don't seem to be holding a charge so I'll probably pull those and see if I can charge them one at a time. The rig has already killed 2 chassis batteries that I replaced and now the new ones are low as well.

I think at this point it's pretty obvious that these batteries should be charging and they aren't because My rig is plugged into shore power 24/7 IMHO it's either both relays went bad, the big boy is bad or the inverter is bad. I'm voting inverter but seeing as it costs $1500 I'll replace the big boy first and order a relay just in case. Even with both battery switches off my batteries are draining in a few days so I need to try something soon so I don't have to keep buying new batteries.

Unless someone has further insight I'm going to order parts tomorrow.

Ray,IN 08-09-2021 06:26 PM

This might be helpful: The 12volt Side of Life (Part 1) The website explains in detail how your battery bank should be wired and all thing 12V. Don't skip page 2 even though you don't have solar.

K7JV 08-09-2021 09:03 PM

Dallas, you probably aren't on a bad track. Your batteries may or may not be bad, but I do want to give you some insight into how four 6-volt batteries work. They are connected so that there are two sets of two, both of which are connected "in series". That means that the negative pole on one is connected to the positive pole on the second one. The remaining positive and negative poles will read 12 volts. You can think of those two 6-volt batteries connected in series as being a rather large 12-volt battery.

You have two pairs of those. They are connected "in parallel" with each other, which means the two outer positive posts are connected together and the two outer negative posts are connected together. That gives you two sets of two batteries that will provide energy at approximately 12 volts, but at twice the amperage and energy capability of just two of those batteries.

There is no place where anything other than 6 volts or 12 volts will be found in that 4-battery installation. You should definitely NOT see 25 volts anywhere in your coach.

If you were so inclined, you could drive your coach to a facility that sells batteries such as Interstate, or Batteries Plus, or Costco, and they could load test them for you to determine whether they are really at the end of their life.

I wish you were close to me, but chances are SW Idaho is a long ways from where you are located. I agree with replacing the BigBoy, as 0.6 volts is getting a bit high.

Your chassis battery should be good for several months if you open the disconnect switch that is probably on the left wall of your battery compartment. If you are sure to turn off the inverter, you should be able to get several weeks on your house batteries with that disconnect open, as well. THERE IS AN EXCEPTION - Your CO alarm and your Propane alarm both draw enough current to become a problem. For long term storage, you can pull those two fuses, but be sure to put them back in before using your coach. Those two fuses are in your front run panel in front of your front left wheel. Your inverter can be a bit of a drag as well. Also, be sure to turn off your refrigerator. It is on the battery side of that house battery disconnect switch. Part of the AquaHot control system is on the battery side of your house battery disconnect as well, but the draw is minimal once the unit shuts down.

When you look at your BigBoy relay, one of the large terminals is connected to your house battery and the other is connected to your chassis battery. If you are reading a fraction of a volt between those two terminals, and you are connected to shore power or running your generator, your batteries are both charging.

Wow, I wish I could be there to help you, in person. Way too much to try to describe in a website user group. Dang! Keep us posted what you find.

dallas121469 08-09-2021 10:45 PM

I'm actually in east Idaho. Didn't realize my location wasn't listed. I noticed the battery set up that you noted. For now I just unplugged from shore power and disconnected all the batteries. I've taken batteries to auto stores to test them and may do so but for now I e got six batteries to charge and a Big boy to install. After that we'll see how things look. The chassis batteries are draining in a few days with or without the disconnect flipped. I didn't want to replace my coach batteries yet because I was going to get a couple lithiums and some solar panels next year.

Anyway. For the next couple days I just need to charge batteries. I'll keep ya posted

dallas121469 08-15-2021 10:37 AM

New big boy installed, internal fault error. Turned off every single breaker except for inverter, internal fault error. Unplugged shore power and tried inverting instead of charging, internal fault error. I'm now nearly convinced that it's a bad inverter.

That being said, can the inverter be repaired? And if so by whom? I did read one instance where someone was able to get theirs repaired at a marina and that it just needed a new circuit board.

Thanks, Steve

Addendum: it's supposed to cool off later this week so Im just going to pull the inverter and inspect the internals.

dallas121469 08-15-2021 11:10 AM

Realized that I didn't have to remove the entire unit to inspect it so did it today. Visually everything looks good but I obviously can't see everything. I'll see about getting a control board tomorrow or finding someone to fix it.

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