Magnum Fault! No Comm

[Amg]

I am currently waiting for an appointment to get my Magnum invertor checked out for the problem described above. Unfortunately Airstream dealers are booked up over six weeks.

I know LEW indicated there is no relationship to the invertor and A/C from either the generator or being plugged in. However even when not using the invertor, sporadically the invertor will turn to Comm fault when I start the generator. Further when it does that my TV has no power. Somehow the TV must go through the invertor. I don't seem to have that problem when I have the unit plugged in. Can the quality of electricity from the generator be causing the fault? Don't understand why TV won't work when use generator, the invertor is not on invert, and all other A/C is functioning. Again it is sporadic and I am able to clear faults by rebooting power system. Any thoughts would be appreciated

[lewster]

Your TV circuit is connected to the 'pass-thru' circuit of the inverter. This allows you to watch TV ( and power whatever else is connected thru the inverter) when on battery alone, but will also energize those circuits when shore/ gen. power is available.

If you are repeatedly getting a fault, especially when starting the generator, the inverter low voltage disconnect is probably set too high.

The high transient draw from starting the generator is obviously causing s low voltage fault in the Magnum.

I would also suspect the condition of your batteries, as they should not be drawn down so far when starting the gen. Both devices are wired to your house battery bank. You should have your batteries tested for capacity soon!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

[Amg]

LEW, thanks

I purchased unit new six months ago. I had it built and it sat on lot three weeks before I could pick it up. Suspicious of batteries then and had them replace them. Unit is always plugged in when not in use. Will have batteries checked again

[lewster]

Originally Posted by Amg

LEW, thanks

I purchased unit new six months ago. I had it built and it sat on lot three weeks before I could pick it up. Suspicious of batteries then and had them replace them. Unit is always plugged in when not in use. Will have batteries checked again

Your Magnum has a 2 year factory warranty. Any Magnum authorized service center can test it for you. I would venture a guess that most Airstream dealers (make that most RV dealers in general) have no clue about how to test a Magnum and considering it is still under warranty, you should have Magnum involved in the process, unless Airstream will cover it under their warranty and replace it!

[Amg]

A quick follow up. My unit was at the dealer for three weeks trying to diagnose the magnum problem. They said they found it to be a bad solenoid. Mine was installed at the factory, others had a service bulletin upgrade. Took the coach home yesterday and the problem was worse. The Magnum was as dead as a door nail. When I put the generator on it said no communication Just left the coach at the dealer. A quick diagnoses indicated another bad solenoid. Dealer said he is not allowed to remove it But we agreed a new one won't be connected. I guess their service bulletins creates problems. Hopefully will get coach back next week and maybe it is fixed.

[Mcrid]

Is this the solenoid added as a result of Service Bulletin 164?

[Amg]

Yes same solenoid. This is second one that was defective. For some reason the factory in order to do the repair is insisting a new one be installed. The dealer agreed to install it but it will not be connected. I cannot understand why the factory was so insistent. It can't be a safety problem not having one.

[lewster]

Originally Posted by Amg

Yes same solenoid. This is second one that was defective. For some reason the factory in order to do the repair is insisting a new one be installed. The dealer agreed to install it but it will not be connected. I cannot understand why the factory was so insistent. It can't be a safety problem not having one.

It has nothing to do with safety! It has everything to do with Airstream trying to CYA for a charging system design that has some serious flaws.

As I have been told by some recent clients with new Grand Tours, the problem of extreme battery drain is a function of leaving the inverter in the 'ON' position when not in use. The Magnum will burn a parasitic load in excess of 1.5 amps while it is 'idling' and in stand-by mode. This does not happen if the inverter is switched 'OFF'.

I counsel all of my clients to consciously turn the inverter to 'ON' when in use and 'OFF when that use is finished. It's just like turning a light bulb on when entering a room and off upon exit. Of course, they really don't NEED to do this as most have greatly enhanced battery banks and 400 watts of solar that really work in keeping their batteries charged.

The solenoid is wired into the positive inverter DC line coming from the batteries. It is meant to solve the problem of inverter parasitic loads. A more simplistic fix would be to use a Blue Sea Systems Series M rotary switch positioned in the front panel of the electrical center (just like your motorized disconnect switch) and simply turn it off when not using the inverter or needing it's 120VAC pass-thru function.

I also do this in all of my installations to be ably to isolate the inverter if a hard re-set is required. Sure beats disconnecting battery cables!!!

[lewster]

Just noticed what the solenoid that's used in the 'recall' draws. It's a continual 0.72amps!!!!!

I'm in the middle of a Grand Tour solar/ lithium/ Magnum upgrade and when I went to remove the old inverter cables, I noticed that the solenoid in question was HOT....... Like over 125 deg. !!!!!

I measured the amp draw just before removing the device, as it is no longer needed when I do a full upgrade.

It would have been simple to use a latching solenoid that draws NOTHING after the contacts have been engaged. Just another cheap, essentially worthless 'feel good' upgrade!!!!!!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters***Victron Energy Components
541-490-6357

[Amg]

Just picked up coach. Still has selenoid but disconnected. Hopefully problem is now solved.

[Protagonist]

Originally Posted by lewster

The Magnum will burn a parasitic load in excess of 1.5 amps while it is 'idling' and in stand-by mode.

Originally Posted by lewster

Just noticed what the solenoid that's used in the 'recall' draws. It's a continual 0.72amps!!!!!

So without the solenoid the house batteries could be drained to a 50% charge state in about two days of non-use. With the solenoid, they would be drained in five days of non-use. I am underwhelmed.

[lewster]

I still can't fathom why the manual marine disconnect switch is not the preferred method of isolating the batteries or the inverter. I use them on every installation that I do and they have a ZERO amp draw.

[Boxster1971]

Originally Posted by lewster

I still can't fathom why the manual marine disconnect switch is not the preferred method of isolating the batteries or the inverter. I use them on every installation that I do and they have a ZERO amp draw.

Lew - I agree with you. It was obviously a typical corporate money driven decision to use a cheap solenoid. Form the pictures of that solenoid that I've seen it looks like the cheapest one you can buy.


- - Mike
2013 Lounge EXT on 2012 Sprinter

[J&J In A Can]

I finally found what was causing the the "Fault! No Comm" message from the magnum inverter. In my case, the positive battery cable to the inverter was not fully connected. The nut on the terminal only had about three turns on it, so the cable was loose. As soon as the the nut was torqued down, the problem vanished. For what it's worth.

[lewster]

Originally Posted by LoveToWander

I finally found what was causing the the "Fault! No Comm" message from the magnum inverter. In my case, the positive battery cable to the inverter was not fully connected. The nut on the terminal only had about three turns on it, so the cable was loose. As soon as the the nut was torqued down, the problem vanished. For what it's worth.

.............and I wonder who did that???????

[rmkrum]

Gremlins?

Mougwai?

Can't imagine....


Sent from my pocket Internet using Airstream Forums

[Boxster1971]

Originally Posted by LoveToWander

I finally found what was causing the the "Fault! No Comm" message from the magnum inverter. In my case, the positive battery cable to the inverter was not fully connected. The nut on the terminal only had about three turns on it, so the cable was loose. As soon as the the nut was torqued down, the problem vanished. For what it's worth.

Sounds familiar. The only real problem I've had with my Interstate was caused by a loose connection of a large terminal lug on the Battery Isolation Manager (BIM). My tank monitor panel was intermittently not working. I was able to isolate the problem with a phone call to an electrician at my dealer, Colonial Airstream in NJ.

I'm sure in the rush of production an occasional connector doesn't get tightened fully. My lesson learned was to check connections first thing if you are having any strange behavior in your systems.


- - Mike
2013 Lounge EXT on 2012 Sprinter

[amirm]

Having nearly had a fire with loose battery terminals on my boat house battery, that is the first thing I check now. I grab all the cables and tug left and right. No movement should be there. I also test for elevated temps by touching the terminals. On my boat, insulation around the terminals was completely melted!

[Njg]

Just had the same issue with my brand new 2016 interstate. The 80 amp solenoid before the inverter went out and needed to be replaced, literally the day after I took delivery. Late post to the topic here, but wanted to add to the knowledge base.

[Amg]

I had two selenoids replaced until I had it disconnected. No problems now