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Odd Inverter Issue..


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Hi folks!

I have an odd inverter issue that seems to be cropping up. For some time now I've seen that the microwave resets and goes back to displaying 'Simply the Best' and looses the clock. Ie, it's as if the microwave was power cycled even though I am plugged into GOOD 50 amp shore power. 

Tonight the fridge started beeping saying 'NO AC' at the same time the microwave display was off. Same with the TV. What I realized was that all the inverter outlets were dead. I went outside and checked the inverter. Both breakers were OK and the fan was on. I tripped them both anyway. The green light on the inverter was blinking very fast. I verified that the 50 amp plug at the receptacle was tightly seated. Neighbors all had power and so did I (on other outlets) so it was not a power failure.

I went inside and turned the inverter on and the power came back to the outlets. I then turned it off and at some point, not sure when, normal operation resumed....inverter outlets were powered whether or not the inverter was on (normal behavior).

It behaved as if power was cut to the inverter (power failure). Is there anything that comes to mind that could cause that even if the power to the inverter has not been cut?

I realize it's an odd issue but this is the first that I was able to witness it. I hope my inverter is not going south...if it happens again, and I think it will, I will be able to watch it more closely and hopefully ascertain exactly what it's doing. But it seems to be, intermittently, thinking that the power going to the inverter has failed...even when it hasn't....

 

Edited by Bob Jones
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I'm certainly not an expert on the electrical, but this does not sound like an inverter issue.  Perhaps a transfer switch is the problem.  The inverter, changes 12v DC to AC and should not really be involved if you are plugged into 50amp service.  I'm sure someone else with a lot more knowledge will weigh in on this.

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Bob,

Electrical problems are not in my realm of things to work on, this problem sounds like maybe one or more connections in the transfer switch may be loose and need tightening. When working in the transfer switch please use all electrical safety measures.

Bill B 07 Dynasty

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1 hour ago, redstickbill said:

Bob,

Electrical problems are not in my realm of things to work on, this problem sounds like maybe one or more connections in the transfer switch may be loose and need tightening. When working in the transfer switch please use all electrical safety measures.

Bill B 07 Dynasty

What inverter do you have??

It probably wouldn't hurt to access the inside of the inverter and check the connections.  On mine there is a power strip with screws holding both the in/out romex wire.  I'd all check the connections at the main service panel and the inverter subpanel.

If that isn't the problem it the inverter may be developing a problem with the internal transfer switch (pass through power relays). 

When I thought I had an inverter problem I called the tech support line and that person steered me in the wrong direction.  I actually pulled the inverter out thinking I was going to have to replace.  I then called Inverter Sales and Service (they have multiple locations) 1-615-285-0611 and after explaining the symptoms he said he didn't think it was an inverter problem and suggested I reinstall the inverter and bypass and how to isolate individual circuits and was able to solve my problem, which wasn't with the inverter. 

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First, when attempting to troubleshoot electrical problems, you need to separate them so that one doesn't play into the others.

You have various sources/devices that can generate power to your coach.

Shore power - 240 VAC split into TWO separate 120 VAC circuits or 30/20/15 amp supplying 120 VAC to all circuits.

Generator - supplying 120 VAC to all circuits.

Inverter - supplying 120 VAC to some circuits by converting 12 VDC to 120 VAC MSW or PSW. Your Inverter also charges batteries when either hooked to shore power or generator power.

House Batteries - 12 VDC powering all 12 VDC circuits.

If you are having a 120 VAC problem it's best to disable the Inverter completely so you can focus on either the shore power supply or the generator power supply. Once you have confirmed that neither one of them is causing your problems then you disconnect all 120 VAC power, shore and generator, and turn on your Inverter so that it is the ONLY device supplying power to your coach.

Once you have done all that you will have a better idea as to what is going on with your electrical systems.

 

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My limited knowledge of the electrical circuits in motor homes..... I believe the things that the inverter powers by "inverting" 12vdc into 110vac are all powered "thru" the inverter. TV microwave refrig and limited outlets..... 

When there is other power available (genny, shore power) to the inverter it passes that power (by way of internal-to-the-inverter relays or transfer switch) to those (TV, Micro etc) outlets.

It sounds to me like the internal to the inverter relays are losing contact, for whatever reason (loose, dirty, worn out) 

Ken

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I don't understand wok that you wrote.  You may have more than one problem confusing things.  You said the microwave and TV when off when the problem occurred. Then you state inverter outlets were powered regardless of whether r not the inverterwas on.  But the microwave & TV are on the inverter.  First you need to determine what the inverter/ charger is doing.  Is it switching to inverter mode indicating it is not seeing 110VAC input?  If so, the problem might be before the inverter. I'd it is not switching to inverter when there is lots of 110VAC, then it might be an inverter problem.  The fact that the refrigerator shows no power (that is a common message on propane refrigerators), indicates a power outage.  If this message is on a residential refrigerator, which would normally be connected to the inverter, it indicates an inverter problem.  Can you be more specific as to what happens at what times, what they are connected to, and what the inverter remote panel indicates, and if the inverter is turned on or not.  It's not clear if this is more than one issue at the same time.

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24 minutes ago, waterskier_1 said:

It's not clear if this is more than one issue at the same time.

Totally agree! He needs to separate out exactly what his problem is and then explain it in detail in another post before we can help.

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Thanks for the replies people!

As I said, this appears to be a new intermittent issue. The only clue I had that something was going on was coming home to see that the microwave had been power cycled for some reason.. until last night when the issue happened while I was in the unit. 

So, to keep it simple, last night all the inverter circuits lost power despite the fact that shore power was present.

I don't know (yet) what caused them to come back on. I am guessing this is what has been happening when I've been away and come home to see that the microwave has power cycled.

The inverter is a Trace Engineering Legend Series 1500 watt MSW inverter. As part of maintenance I had already tightened connections in the transfer switch box (shore/genset/inverter) and also at the breaker panel inside the unit. I had also tightened the strip that holds the romex wire in the inverter itself (I knew that vibrations can cause those connections to loosen).

@jacwjames "If that isn't the problem it the inverter may be developing a problem with the internal transfer switch (pass through power relays)."

This was the first thought that crossed my mind, even though I know little about how the inverter actually works. If AC is present at the Inverter and then power drops to the inverter's outlets on an intermittent basis, that would make perfect sense. I would guess that other than the fan, the relays are probably the only moving parts in the unit.

@Joel & Suzanna "Weak connections start fires so I would not ignore this issue."

Agreed. I don't like it and it seems serious to me. 

I still have an account at DigiKey, it may be time to pull the inverter, read the numbers on the relays, and order some in. 

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Ok.  You state the the inverter outlets lost power despite the fact shore power was present.  Note are you determining that shore power was present?  With a vote meter?  Where did you measure the voltage.  Or are you simply stating that the coach was plugged in?  What is important is to confirm that the inverter had shore power to it.  If it did, it should have just passed thru it.   I don't have a schematic of that inverter, so I can't say when the internal "transfer relays" are deenergized & when they are energized.  But it is not likely that they are randomly changing state all by themselves (and back again).  If that is happening, it's more likely the control circuit that is rejected p responsible, so randomly changing out relays may be futile.  It is most important to know for sure that when this error occurs, that we know for sure that the inverter has power at the input.  It would also be helpful to know what is displayed on the inverter remote panel when this is occurring.  

Before you mentioned that the refrigerator started beeping & showed NO AC. Is this a residential refrigerator connected to the inverter, or a Norcold connected to shore power?   I'm leaning to intermittent shore power issues, but the only explanation for loss on AC on the inverter outlets souk be the inverter is turned OFF. Is that possible? 

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It's very easy to determine shore power was present - all the other electrical outlets in the unit work, ie, the clothes washer was still running, the hot water tank was still on etc. Only the *inverter* outlets had no power. I agree that it could be a solid state error, ie, that control of the pass-through relay may have an issue. But, since it's intermittent, and the unit is 20 years old, my guess is that relay has performed yeoman service and probably needs a break 🙂 (pardon the humor)

The refrigerator is a Norcold. The only reason I knew the issue was occuring was because I heard it beeping about no AC. 

Right now I'm tripping the breaker to the inverter every 30 minutes or so (cutting and resuming power) to exercise that relay but I suspect replacing them would not be expensive and probably stand a high chance of solving it. I will take a look in the owner's manual shortly as I think it describes the operation and may help narrow it down. 

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Update: I took the case of the inverter and from what I can see, there is only one relay in it. It's a Deltrol Controls 23523-70 and it's still widely available. Looks like it's about $60 all in.

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Ok, let me summarize to make sure I got it.  The inverter outlets went off.  You think you still had shore power because the w/d and egoistic water heater were working, but the refrigerator was not.  Only the ice maker on that refrigerator should be connected to the inverter.  The rest of the refrigerator is on its one AC breaker - not on the inverter.  So it seems some of the AC was working, but some was not. 

I'm now wondering is you are losing one leg of the 220 shore power (assuming you are on 50-Amp service). What do you have for "surge protector or energy management system usually installed prior to the main transfer switch?  If it something like the Progressive EMS, it will kill the leg once the voltage drops below 105 Volts.  It will keep it off until it sees void power for several minutes, then it will re-engage, and everything wok start working again, all without user involvement.  Is this a possibility?  Are the W/D & electric water heater on the same leg of the incoming 220-VAC?  Are the inverter & refrigerator on the other leg? 

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Try giving these guys a call, Inverter Sales and Service (they have multiple locations) 1-615-285-0611

When I was having trouble I talked to them, saved me a lot of time and $$$$. 

I looked at a manual for a Trace 1500 inverter, it showed only one line in and one line out.  So if it is an internal transfer switch there is only one.  When I called the Trace help line they told me the internal transfer switches for my RV2012 were obsolete.  I did take my inverter out and pulled the cover off, not easy to get to the internal transfer switches, the Trace tech said some people buy external ones and go that route. 

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Hi Jim!

I think you probably nailed it with respect to the internal transfer switch (hereafter, relay). You are correct, my inverter appears to have a power in line and power out. I'm assuming the feed to the inverter comes from the breaker panel above my bed and that the feed going out of the inverter goes to the outlets it powers. Other than that, two large DC cables at the rear connected to the batteries.

The relay is pretty easy to get at on mine and I have a hot air rework soldering station with all the goodies. So replacing it would be easy. But, if I'm in there I would also use my ultrasonic cleaner on the boards and get them like new. To be honest, I wanted to go in there and clean it for some time (I know, it's odd, but I have the gear to do it). It's a beautiful conformal coated board and I have a good multimeter so I could even test the capacitors and resistors etc. 

According to Deltrol, that relay is rated: Expected Life Electrical at Rated Load (Min.) 100,000 Operations | Mechanical Life 10,000,000 Operations

This makes me wonder if it's even required to replace the relay. I'm wondering if a few minutes with a points file on the contacts would case it. It does look like the plastic cover on the relay is removable...and I did see some posts from others that had a similar issue with their relay and one fella used DeOxIt on it and said it was good for 4 years since his 'repair' 🙂 I did look up the people you recommended calling, they are closed until Monday. 

If 'our' suspicions are right I could have this thing done by tomorrow.

@waterskier - Only the inverter outlets dropped off-line. The rest of the outlets continued to have power. My Norcold is entirely powered by the inverter, it seems Monaco's really are snowflakes 🙂 There is no energy management on this unit. It's a 2000 Diplomat so it's pretty basic in that respect. 50 Amps from the pedestal to the transfer switch and then it looks like the power feed to the inverter is on a circuit breaker in my bedroom. That's about it. The power in this park is very good, there is virtually no chance of a feed issue. 

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Bob,

Sounds like you are capable of fixing the inverter.   Easy access to the relay is a good start. 

Once I took the cover off of mine I was certain that I wouldn't be going any further.  Luckily the advice I got from Inverter Sales and Service was right on the money and ultimately I was able to fix my electrical problem.

Good luck, keep us posted on your progress.

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No way man, we're in this together 😉

I'm about to pull the inverter, which means, you won't hear from me for a while because the Internet and TV and all the important things run off the inverter. If you don't hear from me for a long time, it's because I have received a massive shock and am in need of defibrillation, which will probably never come as I am here alone 🙂

I'll take pictures so you guys can live vicariously through me without doing any of the work! 🙂

First stop will be putting the inverter on my desk, draining the capacitors and then examining the contacts on the relay. If they look good, then there is probably no point in going further. Back soon..wish me luck! 🙂

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1 hour ago, waterskier_1 said:

You could simply wirenut the 110VAC input and output of the inverter together, since you're taking them off anyway that way you'll have a place to plug in you solder station. 

Hahaha - great minds think alike! I came to that same conclusion when I started disconnecting and everything in the motorhome went off. And then it came to me, why not just wire the input and the output together and away you go? After that, I realized that everything in the motorhome that runs on 12v was going to kill the coach batteries because the charger has been removed. So I had to put a temporary charger in there too!

One of the pics shows the clear plastic case of the relay which is the suspect. 

20210821_162503.jpg

20210821_162508.jpg

20210821_162639.jpg

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I got the board out and cleaned up as well as the rest of the inverter. I took the cover off of the relay and there was corrosion on one of the terminals and signs of wear on the others. It's very hard to determine how bad it is without removing it from the board. I ordered up a new relay because if I have to remove it from the board, might as well put a new one in. $75 CAD delivered. I think it's worth the shot and now that I've jimmied power to the motorhome I can wait for the shipping.....

The board is held in place with plastic rivets which will need to be replaced. Add in another $25 and I'm into it for $100 even. I suspect it will work 🙂

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The plastic rivets are about $5, in the USA - not sure about CA.  Depending on size, you might get them at an auto parts store.  I buy mine in quantities on eBay.  

Yes, you'll need a charge source for the batteries if you plan on not reinstalling for an extended time, and don't have solar. 

Best of luck on the relay replacement fixing the problem. 

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When I had my inverter out I was not using the RV, it was in the garage.   I went ahead and taped up the +/- 12 volt cables, and then 120 volt leads just to be on the safe side.  But one thing that baffled me was that when the inverter out I could not get any 12 volt circuits to work even though I had the 12 volt disconnect on.  I did put a small battery charger on the house batteries but that didn't help. 

When I put the inverter back in and hooked up the 12 volt leads but bypassed the 120 volt system the 12 volt circuits in the motorhome worked.  This allowed me to trouble shoot the 120 volt circuit and ultimately solve my problem. 

So in the future, if I have to bypass/remove the inverter how do I get the 12 volt circuits to work.

 

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Hi Jim - I don't know how you couldn't have 12v if the disconnect switch to the coach batteries was not turned off. Yours must be wired differently than mine?

As you can see in the pic, on mine I did not disconnect the battery cables from anywhere other than at the back of the inverter. Do you have some kind of battery management system or something that could interfere with the 12v? I'd have to see a picture of how it's wired to come up with an idea on that one. 

My system/motorhome is pretty simple in that respect. There is no other battery management than the inverter. 

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I had my voltmeter out even checking the entire system.  Could not figure out why I wasn't getting 12 volt to the house.  I never did figure it out but solved my problem by installing the inverter and attaching the 12 volt cables and all the control wires.  Not sure if one of the control wires would have had something to do with it. 

I guess this problem is for another day, got too many irons in the fire already.

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