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dallas121469 08-03-2021 09:38 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 08-04-2021 12:01 AM

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 09:57 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 10:52 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 11:35 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 08:10 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 08:30 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 08:36 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 06:46 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 07:26 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 10:03 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 11:45 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 11:37 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 12:10 PM

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.

RayAZ 08-15-2021 02:35 PM


Originally Posted by dallas121469 (Post 5874346)
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.

Try this guy I've been watching at his videos on YouTube , ill add the link .

PCS Electronics 573-814-3131

dallas121469 09-08-2021 01:17 PM

Update and question
I put the inverter problems on the back burner while attending to some home repairs that need to be done before winter and now I'm back at it.

I found a company on the east coast that can test to see if it is my control board or FET board is bad but after round trip shipping, the headaches of removal and reinstall and their bench test fee I'm pretty close to the same price as a control board from them. The FET board on the other hand is another story. Control board is $300, FET board is $600 and it sounds like neither one is available until at least November thanks to the worldwide chip shortage.

I still think its more likely to be the control board but I don't know much about the FET board, it's function or if it typically goes bad. Even with the price of both boards I'm still out less than the cost of a new Inverter. The RV places around here wan't three grand for a new inverter of my type.

Anyone have some information on these FET boards? Thanks.

dssl 09-08-2021 09:20 PM

3k for an inverter? What kind is it and how many watts? You can get a Magnum or victron 3k pure sign wave hybrid Inverter for under 2k.

dallas121469 09-09-2021 12:16 AM


Originally Posted by dssl (Post 5906986)
3k for an inverter? What kind is it and how many watts? You can get a Magnum or victron 3k pure sign wave hybrid Inverter for under 2k.

I'm not stupid. I know They're just trying to rip me off but I didn't bite. Nobody within 200 miles of me will repair inverters. They all just want me to buy a new one. One place even told me a new board would cost as much as a new inverter so I should just buy a new one. And people wonder why I do l my own repairs and maintenance .the only place that has been helpful is a marine and solar place in Florida. I ordered the control board today through them and I might get it this year.

I'm sure there are other good companies out there but I always seem to get the worst ones when I need parts or repairs. You should read my post about trying to find a new AC unit.

They think every is a helpless rube and when you call them out they get pissed.They know there is a shortage so can jack the price up. Not all places quoted me $3k.

dssl 09-09-2021 01:48 PM

I too am handy and try to not spend more money then is needed but whenever something breaks you have to decide if it's better to replace or repair. A $600 dollar part that you are not sure if it will fix an old inverter that depending on the model may be replaced for $1300 or (magnum 2k PSW). Clearly you have to consider the actual replacement cost and the parts cost and if you think the item will be as good as a new one as well as how much hassle you are willing to take on.

I don't believe there is an inverter shortage.

The reason I am familiar with inverter prices and availability and why a $600 inveter part seems questionable is I recently purchased a like new Magnum 2k PSW inverter for $600 plus $75 for shipping for an electrical upgradeI am planning. I am trying to decide if I should use it or sell it and install a 3k hybrid inverter.

andy29847 09-09-2021 03:43 PM

I like to read all the electrical threads. I was an apprentice electrician back in the 70's, and switched to a telephone job for a carreer. I've had some training and I have a little apptitude. Having said that, inverters/converters/chargers can be mysterious. In my 4 years of motorhome ownership (2001 Apline Coach), I have had a couple of problems that I thought were inverter issues, and they turned out to be something else. Reading some of your posts make me believe that you have some of the same misconceptions about how things work that I had. I'm going to share some of the fundementals I have learned with the caveat that your coach may be different.

I have an inverter/charger. Some people have inverters/converter/chargers.

Since I have an inverter/charger, all 12v power comes from the batteries.

My inverter/charger will only charge the house batteries unless there is another piece of equipment to sense when the house batteries are fully charged, and transfer the charge to the chassis batteries. On my coach, an Echo Charger performs this function.

The path of power through the coach is more complex than I expected. It was a while before I understood the reason for 2 panels. I also have some 12v items (steps, refrigerator, 12v fuse panel) wired directly to the batteries. I made a diagram that helps me keep this straight in my mind.

On shore power, power comes through the transfer switch to the main panel, from the main panel to the inverter/charger, then AC is passed through the inverter/charger to the sub panel. My sub panel feeds the microwave and a few lights and recepticles. The items that work from the sub panel are the ones that will work when using the inverter function.

Generator power functions the same as shore power.

Battery power feeds the previously mentioned items that are directly connected to the batteries plus the items in the sub panel.

Batteries are what I always check first. One of my biggest hints is that my step quits working when my house batteries get low.

I have some concern about some how your batteries are connected. The 25v measurement and the statement that you hooked them up like the previous owner are not the same "as I know they are right". Again, I made a diagram for my coach that shows all the power. You should note that the house batteries are connected in 2 parrallel pairs of series wired batteries. To write that another way, 1 & 2 are in series, 3 & 4 are in series, the the 2 pairs are connected in parrallel. This nets the 12-14 volts expected.

My coach also has a sticker on the wall of the battery compartment that shows how the batteries should be connected.

On my recent trip, I had some generator problems which lead to some house battery issues when I had a long travel day. To solve the battery issues, I first made sure they were properly filled with water (should be serviced monthly). My control panel would show readings in the low to mid 12s when my step stopped working. When I hooked up to shore power at the end of the day, my inverter would alarm when trying to recharge the house batteries from their low state. I solved the problem by using a auto battery charge on the house batteries while I camped overnight. After a couple of days of struggle, I realized that I was straining the batteries and the inverter/charger by setting up (jacks and slides while the AC was running) before I hooked up to shore power. My house batteries are 6 to 7 years old, so this might be a sign that they are near end of life. My inverter is OK.

dallas121469 10-30-2021 05:14 PM

Installed new control board today and the inverter appears to be working swimmingly. I haven't tried inverting yet but the charger has been working for a bit now. The inverter is not making funny noises or shutting down. I'll let it charge over night and try inverting tomorrow. If that works I'll button everything up and move onto the next issue: rewiring my new AC to work with the old thermostat and wiring.

Thanks for the help.

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