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Problem with Magnum MS2812

baipin

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Dec 25, 2020
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Having a problem with a used MS2812. It powers a load or remains in search for about 10 seconds then powers itself off until DC input is removed or the inverter is reset. The guy who sold it to me said all was functional and the only maintenance work done to it was having the main board replaced by Magnum/Sensata through Tiffen Motorhomes (it came out of an Allegro motorhome I believe).

The inverter's green LED will blink once when connected to DC as it should (connected to a 12V battery; I have tried with both LiFePO4 and FLA). It will then power on briefly when I press the ON/OFF button beside the LED. If I power it on with no AC load, I will hear a clicking noise from what sounds like right in the transformer; not the relays as far as I can tell. What could possibly be inside a transformer to cause clicking?! It then goes silent and nothing happens when I press the power button again, until I either remove DC input or I hold the button on the inverter for 15 seconds to poerforma soft-reset. If I power the inverter on and then immediately turn on my AC load, the clicking stops, and the load receives power (I tried this with a 10W lightbulb and a 60W lightbulb) for 10 seconds. If I power the invert on, then wait 5 seconds to turn on the AC load, the clicking from the transformer continues for those first 5 seconds without AC load. Once AC load is switch on, then the AC load remains on for 5 more seconds until 10 seconds is up, at which point the inverter shuts itself off and must be reset. I noticed throughout all of this, there is a red, yellow, and green LED lit up on the control board. I believe that all should be lit up and if the yellow one is not, then there is a temperature problem. So according to the LEDs, it's functioning normally.

I have a video describing these issues here: New video by BlPlN

Pay attention to 1:39. The mic on my phone is pretty awful but you can just barely hear the *click click click click...* until about 1:47 when the inverter shuts itself off and must be reset.


Note that the voltage of the LiFePO4 battery was at 14.0V, the FLA battery was at 12.5V, and I was drawing 5A at 12VDC and outputting 0.5A at 120VAC with the 60W lightbulb, which means my 1 ft run of 10AWG should be sufficient. Correct polarity was always observed.

I noticed some suspicious things on this inverter to begin with; the screw terminals on the factory-installed side of the wiring had the screws applied to the insulation of the wires, not the actual copper!! There are witness marks only on the insulation; suggesting it came this way from the Magnum factory, and even when the repairs were made, this was not touched. It's just by pure luck that some copper touched the inside of the screw terminal. On one of the big 1 AWG crimp connections coming off of the FETs, there were a couple loose wires sticking out and near the case. Yeah it's only a few strands, but that's enough to cause a short (and these wires could be carrying 300A)!! I'm pretty shocked by the shoddy workmanship - I'd of expected better from Magnum. This was obviously from the factory like this; no reason those cables would of been replaced. For the crimp connectors that go between the AC board (the one that was replaced) and the transformer's temperature sensors, half the crimps were made on unstripped, insulated wire and not even in the crimp section of the butt splice, but in the strain relief part you're not supposed to crimp!

1619890128790.png

Note that the crimp is finished after where I cut this, meaning the only crimped section was an insulated one. I suppose it's possible they fed both ends of the wire into the same end of the butt splice, but why would they mangle the strain relief? That doesn't really make much sense since replacement boards come with one end (in the pic below, the lower white wire) pre-crimped, and it doesn't look like this:

1619890224136.png


Finally, one of the 3-inch long standoffs to hold this board was found rolling around, beneath the FETs (fortunately, it is not made of a conductive material) and an entire 3.5" long screw is nowhere to be found. Here is what one of the three out of four remaining screws looks like:

1619890270098.png

I'm under the impression there was some shoddy work done when this MS2812 Magnum inverter was first built, and when repairs were done, allegedly under warranty by Magnum themselves.

I purchased this from someone on Facebook Marketplace and have written confirmation that they would take it back if it did not work for any reason. I swear I'm following the correct procedure to test this inverter out:

xhLNj5u.png


Some help with this would be much appreciated.
 
I stumbled on your post looking for information about the quality and satisfaction of the Magnum inverters... so I can't be much help, I'm afraid. I hope you find a solution to your issue, soon.
 
I stumbled on your post looking for information about the quality and satisfaction of the Magnum inverters... so I can't be much help, I'm afraid. I hope you find a solution to your issue, soon.

Thanks. In short I am relatively satisfied with Magnum customer support. The inverters are also well-built, but the previous user sold it to me knowingly broken (despite saying otherwise) - it was broken in a way that came from sustained, hard use, and the AC board was also incorrectly replaced at some point. It was pretty butchered by the time I got it. Had it looked over by a local rep/technician for Magnum and he determined that. have since started a chargeback...
 
Baipin

a couple of things I see here, cable size.........did you look at Magnum’s recommendation.....My MS4024AE manual recommends 2/0 cable, your inverter will draw more power than mine 4000 watts at 28 volts= 142 amps. 2800 watts at 13 volts = 200 amps........10 ga wire is 30 amps, way too much voltage drop for a Magnum to tolerate, they are very voltage sensitive but beyond that I see sloppy work in there, not of Magnum’s quality...obviously a semi skilled repair but motor home dealers are not the best repair repair places......apparently you have never seen a double crimper ...they are designed to double crimp each end of a crimp in two locations , once on the metal barrel where it joins the wire and a second crimp on the plastic insulation beyond the metal barrel , the purpose of this is to provide wire strain relief....so that crimp on the insulation is the way all professionals do it. It is MIL spec and is done in all industrial equipment. It is also ISO9000 standard, you won’t find that in Chinese gear but it is common practice here in the USA, not so much in consumer gear but all industrial is done that way. Run your test again with proper wire size, mine didn’t like 2 ga., would drop out, 2/0 and all is well, that’s if your are close to the battery, my 428 a.h. pack is way stiffer than any motor home battery

retired electrical engineer.....
david
 
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Baipin

a couple of things I see here, cable size.........did you look at Magnum’s recommendation.....My MS4024AE manual recommends 2/0 cable, your inverter will draw more power than mine 4000 watts at 28 volts= 142 amps. 2800 watts at 13 volts = 200 amps........10 ga wire is 30 amps, way too much voltage drop for a Magnum to tolerate, they are very voltage sensitive but beyond that I see sloppy work in there, not of Magnum’s quality...obviously a semi skilled repair but motor home dealers are not the best repair repair places......apparently you have never seen a double crimper ...they are designed to double crimp each end of a crimp in two locations , once on the metal barrel where it joins the wire and a second crimp on the plastic insulation beyond the metal barrel , the purpose of this is to provide wire strain relief....so that crimp on the insulation is the way all professionals do it. It is MIL spec and is done in all industrial equipment. It is also ISO9000 standard, you won’t find that in Chinese gear but it is common practice here in the USA, not so much in consumer gear but all industrial is done that way. Run your test again with proper wire size, mine didn’t like 2 ga., would drop out, 2/0 and all is well, that’s if your are close to the battery, my 428 a.h. pack is way stiffer than any motor home battery

retired electrical engineer.....
david

Hi David.

Thanks for your thorough response. I did try with1.5ft long 2/0 AWG cables as well prior to that video. The 10AWG is all I had on hand with those cells in my basement as I didn't want to keep bolting and unbolting the 2/0 lugs. In any case, no difference in performance. I was only powering a 10W lightbulb to try the diagnostic test in the manual (which it could not even complete) so I can't imagine voltage would of dropped that much with less than 1A of current.

As for the crimps; what you say makes sense for the factory-installed side of the replacement board, though the side installed by Tiffen Motorhome did not do that, and it was crimped on the insulation.

1622394436414.png

As in, the wire wasn't even stripped (and of the four wires like this, one did pull out of one of the crimps, I should add, to confirm this). It was just making contact by luck of the factory strands butting up against it. I get the feeling whoever installed this may of throught the crimp acted like a T-splice or something, that cuts through the insulation?! It'd make sense given it also came like this:

1622394247604.png

Note the witness mark on the orange insulation? The white wire on the right and the blue wire between the red and orange, both had the same thing going on. Again, just by luck, some of the strands happened to the brushing against the terminal block, but the strands themselves were not clamped down.
 
That is some sloppy work, it should never be done like that, unfortunately motor home repair shops employ mechanics who can’t pass the standard tests for auto mechanics.......under the law only the propulsion system of the motor home falls under the guidance of the standards agency, none of the motor home living accommodations fall under that agency and outside the guidance of the ?????ASTM?????? I’m probably quoting the wrong certification agency. But in any case the state agency.....here in California its the BAR..The Bureau of Automotive Repair does not regulate motor home coach repairs, that is not a necessary part of the vehicle to run it down the road. It’s cargo......Well that’s our goofy government agencies.....leaving us with unregulated and unskilled repair shops.
You are probably justified in a credit card challenge as that product is now not capable of doing what it was designed to do. That terminal block is the input/output block for the whole unit and that can be traced right back to Magnum itself, there would be no reason for a repair tech to remove wires from the internal side of that terminal block, only the external feed wires should be touched....I’m real happy with Magnum, I bought mine used but Magnum has been there for parts, unfortunately they do not do board level repairs and wanted $375 for a control board, it was a $5 part that I needed to keep the fans from running all the time......did it myself....then again experience.
David....
 
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