Electrical burning, heavy smoke w/ 3yr old grandson sleeping in AI

[pdavitt]

Alex,

What I am about to say may be completely wrong. But, I learned in my professional career to not be afraid of offering trouble shooting ideas.

Basic facts/assumptions:

1. You were on shore power. Which should take the Inverter Section of the device out of the equation.
2. Shore power places the device in "Pass-Through/Charger mode.
3. I suspect that the problem is not related to the AC Pass-Through, or the AC circuitry.
4. The DC charger section and related DC connections are suspect.
5. The Inverter/Charger's chassis ground is a primarily a DC ground. Not to be confused with the AC ground from shore power.
6. The 2018 Airstream Interstate owners manual indicates a 8 AWG chassis ground wire, Magnum's manual recommends 6 AWG.
7. The Inverter/Charger's chassis ground wire should be connected directly to the vehicle's chassis. With no intervening ground posts or buses.

My questions are:

1. What size wire was actually used for the Inverter/Chargers chassis ground, and where did it terminate?
2. Are there any indications that the DC Negative connection to the Inverter/Charger was compromised in any way?
3. Are there any indications that the Inverter/Chargers chassis ground wire connection was compromised in any way?

Like I said earlier, the above may have nothing to do with the failure, but is offered as an investigative path.

Thanks,
Pat

[sajohnson]

Originally Posted by Alex AVI

SAJOHNSON - Yes, the hot smell MANSDERM161 is smelling is definitely not normal. Was not that way prior to my problem and I used to sleep on the side of bed.

Yes, my AI has MMS1012 and schematics seem outdated. (no surprise). Which is why I too was scratching my noggin seeing 1,380w? Where'd that come from? MMS1012 is only 1,000w continuous. Unless they are talking in vicinity of surge power rating at 5min which is 1,200w.

Absolutely -- any hot smell is cause for alarm.

Assuming for a moment that the schematic is accurate, the 1,380W rating could be a conservative rating for the pass-thru wattage.

IOW, when the AI is using shore/gen power, the auto transfer switch (ATS) contacts are capable of handling up to 20A (2,400W) of pass-thru current. The output has a 15A breaker however (not sure why, our MS2000 is 30A in/30A ATS/30A out). So the max pass-thru is reduced to 15A (1,800W).

As you're probably aware, the general rule with breakers (and most fuses) is to de-rate them by 20% to get their continuous current handling capability. So in this case the 15A out becomes 12A.

Still, 12A x 120V = 1,440W, not 1,380W (11.5A). That's not a huge difference, but it is an unusual number.

That's just something I noticed, but it should not be related to the problem you had.

What I keep coming back to is how the A/C would have any effect whatsoever on the inverter. It is clear from the schematic that the A/C has its own breaker (#3) in the main panel. The supply wiring runs straight from bkr #3 to the A/C unit. The inverter is completely uninvolved. I am at a loss as to why the dealer thinks running the A/C will be a good load test of the new Magnum 1012.

One thing I'm still curious about:

The output from th inverter goes to those 3 outlets and then to "1st Relay". Why is the power switched and what controls the "1st Relay"?

Regardless of the answer, I can think of no reason why running the A/C would harm the inverter. The two are independent -- in that the inverter does not handle the power for the A/C.

If I were going to load test an inverter/charger I would:

1) Load the output right to the max sustained limit -- 12A in this case -- and leave those loads running for an extended period.

2) Load the inverter to it's continuous power limit -- 1,000W in this case -- and see if it can handle it for as long as the batteries hold out. For a more prolonged test perhaps a large battery charger could be connected to the coach batteries.

3) With the batteries discharged, set the internal battery charger to the max the coach batteries can safely handle -- about 44A for two GC batteries and make sure it can sustain that output thru the bulk charge stage.

[sajohnson]

Originally Posted by pdavitt

Alex,

What I am about to say may be completely wrong. But, I learned in my professional career to not be afraid of offering trouble shooting ideas.

Basic facts/assumptions:

1. You were on shore power. Which should take the Inverter Section of the device out of the equation.
2. Shore power places the device in "Pass-Through/Charger mode.
3. I suspect that the problem is not related to the AC Pass-Through, or the AC circuitry.
4. The DC charger section and related DC connections are suspect.
5. The Inverter/Charger's chassis ground is a primarily a DC ground. Not to be confused with the AC ground from shore power.
6. The 2018 Airstream Interstate owners manual indicates a 8 AWG chassis ground wire, Magnum's manual recommends 6 AWG.
7. The Inverter/Charger's chassis ground wire should be connected directly to the vehicle's chassis. With no intervening ground posts or buses.

My questions are:

1. What size wire was actually used for the Inverter/Chargers chassis ground, and where did it terminate?
2. Are there any indications that the DC Negative connection to the Inverter/Charger was compromised in any way?
3. Are there any indications that the Inverter/Chargers chassis ground wire connection was compromised in any way?

Like I said earlier, the above may have nothing to do with the failure, but is offered as an investigative path.

Thanks,
Pat

Good observations and questions Pat.

The schematic I'm looking at (attached above) does not seem to indicate the gauge of the chassis ground wire for the inverter. It is here: https://www.airstream.com/wp-content...ers-Manual.pdf

Page 111 / 9-25.

If the schematic you are looking at is different, would you mind posting the link?

I agree with your assumptions. There is/was something else going on, unrelated to the A/C running.

[pdavitt]

Originally Posted by sajohnson

Good observations and questions Pat.

The schematic I'm looking at (attached above) does not seem to indicate the gauge of the chassis ground wire for the inverter. It is here: https://www.airstream.com/wp-content...ers-Manual.pdf

Page 111 / 9-25.

If the schematic you are looking at is different, would you mind posting the link?

I agree with your assumptions. There is/was something else going on, unrelated to the A/C running.

It's on the 12v main schematic page.
Am on my phone or I would go further.

Pat

[sajohnson]

Originally Posted by pdavitt

It's on the 12v main schematic page.
Am on my phone or I would go further.

Pat

Good enough Pat, thanks.

I wasn't thinking...

[sajohnson]

Originally Posted by pdavitt

Alex,

What I am about to say may be completely wrong. But, I learned in my professional career to not be afraid of offering trouble shooting ideas.

Basic facts/assumptions:

1. You were on shore power. Which should take the Inverter Section of the device out of the equation.
2. Shore power places the device in "Pass-Through/Charger mode.
3. I suspect that the problem is not related to the AC Pass-Through, or the AC circuitry.
4. The DC charger section and related DC connections are suspect.
5. The Inverter/Charger's chassis ground is a primarily a DC ground. Not to be confused with the AC ground from shore power.
6. The 2018 Airstream Interstate owners manual indicates a 8 AWG chassis ground wire, Magnum's manual recommends 6 AWG.
7. The Inverter/Charger's chassis ground wire should be connected directly to the vehicle's chassis. With no intervening ground posts or buses.

My questions are:

1. What size wire was actually used for the Inverter/Chargers chassis ground, and where did it terminate?
2. Are there any indications that the DC Negative connection to the Inverter/Charger was compromised in any way?
3. Are there any indications that the Inverter/Chargers chassis ground wire connection was compromised in any way?

Like I said earlier, the above may have nothing to do with the failure, but is offered as an investigative path.

Thanks,
Pat

OK, I went to the 12V Main page. I had attached a screenshot of the section of that page that shows the inverter to an earlier post, #66 -- but I didn't look closely at the chassis ground.

I see what you pointed out in your #6 above. The chassis ground is indicated as #8 gauge. I would suggest following Magnum's recommendations -- and I did when installing our MS2000. AS I recall, there were conflicting opinions as to whether the chassis ground was really necessary, but I installed a #6 ground wire directly to the chassis anyway.

I assume AS was just trying to cut costs by using the smaller gauge wire. From a safety standpoint it _may_ be OK (I don't know what the NEC calls for) but that's a poor place to skimp. Once again, I'm not picking on AS -- our WGO View has a lot of undersize wiring.

[pdavitt]

I don't like talking tech on my phone. Will answer tomorrow when back at my computer.

Pat

[Alex AVI]

SAJOHNSON & PAT - 100% agree. On paper, there is no conceivable reason why the A/C would have any bearing on Magnum burning up. At the risk of sounding like I am defending dealer (I am not, my first experience with them on Firefly issue was horrible at best), they are not going so far as to say A/C is contributing to problem. Rather, they are saying their observation was the problem manisfested itself much sooner with A/C on. I myself had observed that on the following day after incident, when I had more time to try and dig further into electrical load conditions that would induce burning/smoke. It is hard to argue this observable condition. Had I not seen it myself prior to when dealer first laid eyes on it, I would say that's baloney. BTW - this is not lost on Jackson Center's people either, they are baffled just as we are.

So take my word on this, the dealer has no reason to say that had they not observed it. Now, was it coincidence or a red herring. Yes, it may very well be. Keep in mind, we had no intention of replicating the scenario 1,000 times, with the different permutations of ckt brkr combos to establish a valid statistical analysis of what sets of load would really cause problem, i.e. once they visually identify the component smoking and tactile info says it is overheating, that is the obvious first component to replace.

Given the real life conditions that we use our rigs, I have no issue with them testing it by using the AI systems, rather than a controlled bench testing. The unit has all systems on, A/C being forced to go through continuous on/off cycles. Short of me staying in it, I actually feel it is a better test. Besides, my feeling now is if there is something residual going on or other contributory factors, what better way to test than hook the new Magnum to the rest of my original components. The best thing that may happen is if it is going to burn down, let it burn in the dealers shop.

I visited dealer today, sales is open but service is closed. I wanted to pick up some paperwork I needed and thought unit is hooked up outside. No luck. My unit is locked up tight INSIDE the shop. Sales rep can't even get to it. If it burns, it will burn the entire dealership. Looks like they are confident enough to keep unattended indoors. We will see.

[sajohnson]

Originally Posted by pdavitt

I don't like talking tech on my phone. Will answer tomorrow when back at my computer.

Pat

I understand. No rush on my end.

[SSquared]

Alex,

I'm glad no one was injured and your AI hasn't burned to the ground.

Sounds like the schematics are clear about what should be wired to the output of the Magnum. But have you verified that nothing else was improperly wired to that circuit? Like maybe the air conditioner?


And I'm putting a smoke detector into the compartment where my MMS-1012 lives (I have a trailer that came with no inverter; Lewster fixed me up with the Magnum)

[sajohnson]

Originally Posted by SSquared

Alex,

I'm glad no one was injured and your AI hasn't burned to the ground.

Sounds like the schematics are clear about what should be wired to the output of the Magnum. But have you verified that nothing else was improperly wired to that circuit? Like maybe the air conditioner?


And I'm putting a smoke detector into the compartment where my MMS-1012 lives (I have a trailer that came with no inverter; Lewster fixed me up with the Magnum)

Good question SSquared.

Stranger things have happened.

Although, even if something like that were to have been done, there is plenty of overcurrent protection.

I sure hope they tell Alex what they find. Serious failures like this always make me curious as to the cause.

[Alex AVI]

Originally Posted by SSquared

But have you verified that nothing else was improperly wired to that circuit? Like maybe the air conditioner?

And I'm putting a smoke detector into the compartment where my MMS-1012 lives

SSQUARED - Thank you for your thoughts. The quick answer is no, I have not verified everything. Keep in mind this is a 3mo. new unit. My troubleshooting and teardown purpose was NOT to fix the problem. This happened in the mountains of CO. The priority was to triage the situation and to assess if the unit is road-worthy to drive back 550miles.

But to address the tech side of your question, even if that were to happen, there are built-in safeguards that would catch it. Also, something like that would not last the first operation of the either a/c or Magnum. It would just be too catastrophic for the Magnum to survive beyond first use. It has worked well for 3mos.

Yes, AS has directed dealer to install redundant smoke & CO2 detectors as close to enclosure as allowable without intruding on jacknife seat operation. Original ones were immediately yanked and replaced with new, regardless of condition. I plan to push beyond that

[sajohnson]

Originally Posted by Alex AVI

SSQUARED - Thank you for your thoughts. The quick answer is no, I have not verified everything. Keep in mind this is a 3mo. new unit. My troubleshooting and teardown purpose was NOT to fix the problem. This happened in the mountains of CO. The priority was to triage the situation and to assess if the unit is road-worthy to drive back 550miles.

But to address the tech side of your question, even if that were to happen, there are built-in safeguards that would catch it. Also, something like that would not last the first operation of the either a/c or Magnum. It would just be too catastrophic for the Magnum to survive beyond first use. It has worked well for 3mos.

Yes, AS has directed dealer to install redundant smoke & CO2 detectors as close to enclosure as allowable without intruding on jacknife seat operation. Original ones were immediately yanked and replaced with new, regardless of condition. I plan to push beyond that

You're absolutely correct about the safeguards.

Good point about having no trouble for the first 3 months.

I realize all of this is completely hypothetical at this point, but the ATS in the inverter should be able to pass through current to the A/C all day long with no trouble -- in the exceedingly unlikely event that the A/C unit was somehow wired to the inverter output (rather than its dedicated breaker). I'm not trying to be contrary, but it is rated for 20A continuous, most rooftop A/C units draw about 12-13A.

However, that's right at the continuous limit of the 15A output breaker, so it might eventually trip, but even if it did, no harm done.

Of course in the event you had no shore/gen power and the A/C attempted to start, the inverter would almost immediately shut down for low DC input voltage or AC out overload. Ask me how I know...

Again though, no harm done. Magnum inverters are very well protected. It is hard to damage them even if one were to try.

I intentionally wired our MS2000 so that all incoming shore/gen power (30A max) goes through the ATS in the inverter. I feel perfectly safe with that because the ATS contacts are rated for 30A continuous and there are 30A input and output breakers in the inverter. In addition I have a Progressive Industries EMS upstream.

Of course we can talk all day long about how well protected the Magnum 1012 in the AI is, the fact is yours went up in smoke.

That is a very rare occurrence. I sure hope AS and Magnum are forthcoming about the cause.

Enquiring minds want to know.

[Titus]

I assume that it is a CO detector, not a CO2 detector. Regardless, it is hard to see how both CO/CO2 and smoke detectors could have both failed. Were there batteries in both? Does either/both have 12V hardwired and battery power. Perhaps it sat on the dealers lot for months and nobody noticed/cared about the intermittent 'beep' telling of a low battery.

ONOT, I am not sure that an electrical fire would necessarily have high CO/CO2 as there may not be much/any combustion occurring when producing heavy smoke from hot wiring.

[wachuko]

I just want to know what to do if something similar happens in our trip.

Were steps 10-15 enough to isolate the inverter and travel safely back home?

From the moment I realized where the inverter is located, I have worried about something going wrong. From accidental spilling something in the seat (one rule is no drinking or eating in the back seats due to this) or something like what happened to you...

Magnum inverters have a great reputation...not sure what would be better while still fitting in the limited space...

[pdavitt]

Found this article about Inverter/Chargers and grounding on vessels. Applies to RV's also.

https://www.bluesea.com/resources/101

Also these quotes from the Magnum MMS 1012 install guide:

"If installing in a recreational vehicle, do not attempt to use the
vehicle’s metal frame in place of the negative connection or DC
ground. The inverter requires a reliable negative and ground
return path directly to the battery."

"2.2.3 DC Grounding
The MMS should always be connected to a permanent, grounded
wiring system. The idea is to connect the metallic chassis of the
various enclosures together to have them at the same voltage
potential, which reduces the possibility for electric shock. For the
majority of installations, the inverter chassis and the negative battery
conductor are connected to the system’s ground bond via a safety grounding conductor (bare wire or green insulated wire) at only one
point in the system. Per the NEC, the size for the grounding conductor
is usually based on the size of the overcurrent device used in the
DC system. Refer to Table 2-1 to select the appropriate DC ground
wire based on the overcurrent device used for your inverter model.
If the inverter is in a recreational vehicle, DO NOT connect the battery
negative (–) cable to the vehicle’s safety ground. Only connect to
the inverter’s negative battery terminal. If any non-factory installed
appliances are onboard the vehicle, DO NOT ground them at safety
ground. Only ground them at the negative bus of the DC load center
(as applicable)."

Interesting reading,
Pat

[gmillerok1]

Originally Posted by wachuko

I just want to know what to do if something similar happens in our trip.

Were steps 10-15 enough to isolate the inverter and travel safely back home?

From the moment I realized where the inverter is located, I have worried about something going wrong. From accidental spilling something in the seat (one rule is no drinking or eating in the back seats due to this) or something like what happened to you...

Magnum inverters have a great reputation...not sure what would be better while still fitting in the limited space...

Viewing the images of the under side-seat space where the electronics appears AS now places them that you posted when you did the modification to the solar controller and BIM, one thing I noticed is that AS ignores is the requirement by Magnum that the inverter be mounted on non-flammable material, as it can get up to 193F on the surface of the unit. My 2011 did not come with the Magnum, but I later replaced the Triplitte with the Magnum and mounted it on the same material, but one major difference is that in that location, there is plenty of "breathing" space to keep the unit cool, as opposed to the incredibly cramped space under the side seat with virtually little or no ventilation. If it were my unit, I'd try to figure out some way to move some air in that compartment-either a 12vdc thermostatically controlled fan, or at least, some air holes somewhere, to try to keep the unit as cool as possible. I cannot say of course for certain, but it may have been a heat related failure. Using the remote, run the AC and see what the meter readings are for the temperatures for the electronics inside the unit. You may get a clue from those readings if they are extremely high. Of course, the unit should not self destruct in the process, but if Magnum does not expect these unit to bake themselves to death in a small unventilated space, it could happen.

[Boxster1971]

Originally Posted by gmillerok1

Viewing the images of the under side-seat space where the electronics appears AS now places them that you posted when you did the modification to the solar controller and BIM, one thing I noticed is that AS ignores is the requirement by Magnum that the inverter be mounted on non-flammable material, as it can get up to 193F on the surface of the unit. My 2011 did not come with the Magnum, but I later replaced the Triplitte with the Magnum and mounted it on the same material, but one major difference is that in that location, there is plenty of "breathing" space to keep the unit cool, as opposed to the incredibly cramped space under the side seat with virtually little or no ventilation. If it were my unit, I'd try to figure out some way to move some air in that compartment-either a 12vdc thermostatically controlled fan, or at least, some air holes somewhere, to try to keep the unit as cool as possible. I cannot say of course for certain, but it may have been a heat related failure. Using the remote, run the AC and see what the meter readings are for the temperatures for the electronics inside the unit. You may get a clue from those readings if they are extremely high. Of course, the unit should not self destruct in the process, but if Magnum does not expect these unit to bake themselves to death in a small unventilated space, it could happen.

I had similar thought since Airstream now packs everything around the Inverter/Charger much tighter than they did before they started the GT models.

[Alex AVI]

Folks, amazing responses. I forgot my tablet, so bear with me if typos as I am using my teenie smartphone

MIKE, GMILLEROK1 - yes, I do not like that Magnum is installed on a piece of wooden cabinet material (literally bolted into piece of wood). Did not know about Magnum's specific materials recommendation. And the temperature buildup in that compartment could be the link between my Magnum burning when A/C was on. Not the current draw many have been trying to analyze. Also, keep in mind not many places get much hotter than my region in SW


PAT - you bet I will be re-checking their work, the GND'ing points as you posted. I have not told them I would, but they already know me & my background. They know what I will do when I get it back.

TITUS - yes CO detector, not CO2. My bad interchanging them.Dont care about state of batteries. Old detectors out, new ones in. Redundant set being installed near galley. Was told they are battery operated.

WACHUKO - Steps 10-15. Believe it or not, shop foreman interrupted me as I explained to him those exact steps just to detail what measures I took. His exact condescending words "did you know you could've just hit the disconnect switch and just unplug from shore power?" (Step 10-11) like I did not know that. He was getting on my case for the amount of tear down I did. That's when I lit him up with the fact that without a teardown, including galley drawers, fridge, there is NO way to know if embers are still burning inside rendering it unsafe to drive for 9hrs. So in addition to Steps 10-15, I ripped out as much as I can from R/S rear cup holder to microwave portion of galley cabinet.

SAJOHNSON - yes, all the info about how well the Magnum is made and it's safeguards & its reputation does not hold any weight in my eyes coz mine went up in smoke. They are batting 0.000 in my stat sheet. Didn't even get beyond pre-season, yeah?

[Pahaska]

The ground for the Magnum in my AI is a length of #14 wire.

Good info on the mounting material. I'll put spacers under my new Magnum when it gets here. The original mounting location couldn't be worse for ventilation. I improved the venting when I did the twin bed conversion. The new location will be better.