Heart Freedom 458 Inverter "thumping"

We have a Heart Interface 458 Inverter/Converter which is making a "thumping" noise.  The noise is random and everything seems to be working except for this "thunk" sound.  It took us a very long time to zero in on where the noise was coming from.

I've done some internet searches that haven't provided much information.  Tim called the manufacturer who basically said the "control board"  (?) Didn't say circuit board, was probably bad and we'd have to send it in.  That's not gonna work because we are in Wyoming and heading for home in California on Sept 16th.  At that point the rep said, "Well, I guess you need a new inverter".  Oh Joy $$$

We have a RV tech coming out this afternoon, but I just wondered if anyone else has had this problem.

Marsha~

And there are no other symptoms accompanying this noise?  No flickering lights or change in amp readings?  Does it happen only when inverting? Or maybe only when charging (not inverting)?

The only thing I can think of that could "thump" is a relay switching. The Heart has a relay that switches incoming 120vac (shore power) to the output side when available, and switches to the inverter side when not. Maybe it is being told to switch by the circuitry that monitors power status?

Marsha


If it is happening while you are plugged in I'm with Gary, it sounds like the transfer switch solenoid  is not saying closed. Time for a pro?

I would not expect the little relay that is the internal transfer switch to produce a thumping noise as it is about 1cubic inch in size. Not sure what it could be inhe Heart.  Is the MH transfer =switch close to the inverter? That could make a thump when it switches.

Hi guys, this has us stumped, as well as, the Heart people.  Tim has talked to them several times.  The inverter is in a bay and it took a long time to finally find the sound.  It lasts for only a second.  It can happen once, then the next night several times in a row, then another night nothing.  It does not make the sound during the day at all.  We have narrowed it down to outside ambient temperature.  The colder it gets, the more it thumps.  Xantrex is being very generous to us, they heavily discounted a new 458 and are drop shipping it to us (our costs).  Tim is going to switch it out, then send the old one back for them to look at.

Just for more info, the inside wall of the bay also holds several solenoids i.e. slide, bay lights etc.  It also has a very large charging solenoid.  I'm still wondering if that is what is making the noise instead of the inverter.  However, Tim had his hand on the inverter when it made the sound and he could feel the vibration.

On the remote panel we have turned off the "inverter", as well as, the "charging" and the sound goes away.  At least we can now sleep.  For the last several weeks, we have been waiting for the thump and it's been driving both of us crazy....jumping out of bed at 4 AM, grabbing flashlights and waiting for the next "thump".

Forgot, the transfer switch is on the other side of the coach in the electric bay.  The mobile RV tech couldn't pin point anything either.

Marsha~

Just for more info, the inside wall of the bay also holds several solenoids i.e. slide, bay lights etc.  It also has a very large charging solenoid.  I'm still wondering if that is what is making the noise instead of the inverter.  However, Tim had his hand on the inverter when it made the sound and he could feel the vibration.

On the remote panel we have turned off the "inverter", as well as, the "charging" and the sound goes away.  At least we can now sleep. 

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Two things come to mind when reading this particular quote.  The "large charging solenoid" is a much more likely source of the "thump" than the 458.  BTW - turning OFF the charging function of the 458 would probably also cause the charging solenoid to fall silent.  Just a thought.  If the thump is as loud as you say, it probably could be felt while touching anything in the immediate area.

My second thought was the result of a problem an incident that I experienced while parked for a period of time at the beach.  As the temperature dropped in the evenings, one of my rear jacks would settle a small fraction of an inch, and make a "thump", both heard and felt throughout the coach.  This sometimes happened several time a night, and over several days, before the level of the coach was affected enough to be noticed as the problem.  It was a very noticeable "thump".

I'm thinking that it would take a very large relay/solenoid to cause a reaction like the following.

For the last several weeks, we have been waiting for the thump and it's been driving both of us crazy....jumping out of bed at 4 AM, grabbing flashlights and waiting for the next "thump".Marsha~

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Marsha,

I think Lou may be on to something, we have had both Jacks doing thumping as well as the fuel tank.  If possible spend a night with the jacks up and see if it occurs.  Also be sure to have a full fuel tank if you can.

I really don't know of anything in the inverter that could cause a thump of any magnitude as there are no large solenoids or anything else mechanically large.

There is a transformer but that would hum if that were a problem.

We've had the thumping jacks problem in two coaches ourselves, but Tim is no dummy so I am inclined to believe him if he thinks the inverter is the source. OTOH, I have to agree that the inverter has no large relays - it is only switching 30 amps. Doesn't seem like it could make any large noises or vibrations.

Marsha says turning off the Freedom inverter completely (no charging) stops the noise. Hard to argue with that.

Hi guys, the jacks were the first thing we checked.....re-leveled...re-adjusted....no difference; the sound was still there.  When we turn off the "inverter" on the inside control panel, we still had the thump; however when we turned the "charge" off, no thump.

One of the techs seemed to think it could be a wire connection (ie. broken/loose) that with the colder weather was not making contact; another tech thought it might be a power board which Tim had never heard of. 

I just hope replacing the inverter does the trick.

Thanks for all the ideas.

Please excuse me if anyone thinks I was calling Tim a dummy.

Sometimes we have to be a bit skeptical of the problem descriptions we get, but probably not in this case.

I run the freedom 458 also so if anyone needs the manual I can email it to them (too large to post).
The unit does have an over temp shutdown and also a temp compensated charging circuit. Not sure if either of those conditions would cause a thump. Maybe the internal transfer switch inside the unit when going between batter and shore power. If your inverter is in standby and you lose AC power during the night you might hear the thump when it switches over maybe?
Mine is pretty much silent so I?m curious to know what you find.

Mavarick,

That transfer switch is a 30 amp relay just larger than a cubic inch.  You will be hard pressed to hear it, let alone feel it switch.

Lou, no need to apologize, at all.  Any ideas are good ones to consider.

Maverick, we have the manual, thanks for the offer.  We too thought about the internal transfer switch "switching on and off" inside the unit, thinking it might be loss of shore power; but this has been doing the "thumping" since early July in at least 5-6 different campgrounds. 

More food for thought: we leave our inverter on all the time, not just in the stand by mode.  And, it was humming when we were trying to figure out what is going on.  What I can't remember is if it always "hummed".

When we decided to keep the coach instead of getting a new one, we both agreed we'd be ok with repair bills.  However, this has been the year of a new rear A/C-Heat pump, new ice maker and now the new inverter.  Plus we put MD shades in coach everywhere except the front windshield and just bought an RV lot in Wyoming at Star ranch....ca-ching......ca-ching.

Marsha~

I wanted to update/finalize this thread.  When we talked to the Freedom 458 people they could not explain the "thumping" either; but did send us a new unit at a much reduced price!  We received the unit when we got back home in late September, put the coach away and decided we would replace the inverter when we took off for our winter trip after the holidays.

We are now parked in Bakersfield, CA getting ready to take off for Arizona for a few months.  Last Friday, Tim tackled the supposedly "plug and play" replacement.  Well, it's a bit more involved than just plug and play.  There was some internal wiring involved with both removing the old one and installing the new one.  However, he installed the unit, followed the set up procedure to make sure everything was hooked in correctly.  Worked right off the bat.  The remote wall panel unit in the coach retained the settings, so we didn't even have to go through that process of set up.

And, yipee, there is no more "thumping" during the night.  So whatever was a problem in the unit was definitely causing the sound.  When we get back from our winter trip, Tim is going to take the old unit apart and see if there is anything obvious.  He's also thinking of sending it back to the manufacturer, have them look at and if it is a simple fix, repair it.  We always love having spare parts around.....<not>

Marsha~

Marsha


I have had zero luck getting Xantrex to do any repairs for out of warranty equipment but if you are going to PHX after QZ there is a good Xantrex Service Center there,

You were lucky that Xantrex helped you out. Awhile back they were sold to Schneider Electric. Same European company that owns Square D. Customer support has been poor. I called once with a wiring question re the inverter and he told me to get an electrician??? Maybe you charmed them!

Moisheh

I work with power converters (commercial) on a daily basis. Assuming this inverter is similar to 99% of the inverters we come across, there is very little inside of it that can cause a "thump." The only item that comes to mind would be the output reactors. These are usually laminated iron cores with wires wrapped around them. Basically, when current goes through them they become magnetized. If one were loose, it could conceivably "thump" when energized/magnetized. I am not familiar with this particular inverter model, so I could easily be way off base. Some of the smaller units don't even have such reactors.

Another thought occurs that if something were loose NEAR the reactors, it could be "pulled in" toward the case of the reactor and cause a thump. Perhaps something fell close to the inverter and is being "picked up" when the reactors magnetize? I would think that the wires from the batteries would carry a significant amount of current, and that magnetization would be much more powerful than the output reactors. I'd pay particular attention to securing those wires and make sure there is nothing around them. If this inverter is 120VAC at 30 amps, then 12V wires will carry 300A, or 24V wires would carry 150A, assuming no losses. Anyway, that much DC current can move a lot of large items, so if these wires are near something iron or steel, then that thing could be getting move around.

As far as this only happening at night, well, that's anyone's guess. Perhaps something steel is warping with the cold, and being "drummed" when the unit pulls current. Think of a cookie sheet that's heated and cooled. The metal reaches a point where it "pops" back into place. So, if something is warping/distorting with the cold, then the inverter kicks on and warms that metal quickly, it might "thump" when it pops back into place. Of course, everything I've said is pure conjecture. At least it's more things to look for if the thumping continues with the new inverter installed.

Ok...further update with a mystery. 

As I mentioned in a prior message we replaced the Xantrex 458 with a new one and all was well.....for while.  The new inverter started thumping just like the old one, but not nearly as loud. We had planned to go to Apache Junction from the Lake Havasu area so while there Tim called the well-known great Xantrex repair center.  They informed him that Xantrex 2000 watt 458 had a known problem that results in "thumping" of the top of the inverter case which is made out of metal.  It had something to do with the "power module" and that the new ones were not having that problem.  Well, we were.  We took it in to the Mesa Xantrex repair center; they removed the unit, bench tested and found nothing wrong.  Xantrex did agree to replace the power module and the control module.  One thing the tech noticed was that our back two 6 volt deep cell batteries were bulged a slightly leaking.  Took the coach back to Apache Junction then a few days later moved to Palm Springs.  Well, we began hearing a slight very low almost undetectable thump, not enough to wake us, but it was there.  I also think we are super sensitive to the sound. 

At that point, we decided to replace all of our batteries even tho they are only 3 years old- Trojan T-105.  The new batteries have been in for some time now and no thump....at all...nada.  So we are wondering if the battery situation was the problem all along!

Marsha~

I'll bet Tim is in a great mood over that.