Electrical Power Problem

[five]

Today I exercised the generator in the usual manner....let it run for 10 min, turned on all three air conditioners, ran it for another 50 min, shut them down, let it idle for 10 min and shut it down.  While it was running, I went inside and noticed the M/W was not getting power and a box fan I run all the time was running erratically and would not respond to changing speeds with the control knob.  After shutting the generator off, I plugged the coach back in....shore power is fine, we are not on the road.  The M/W did not come on and was making small surging noises, I turned it off with the circuit breaker, the fan was acting the same way as before.  Unplugged shore power and turned off both AC and DC master switches for the coach.  Waited 20 min, turned them back on....no change and no change when I plugged in shore power.  The Magnum remote is showing a red fault light and "FET Overload, DC 12.4/5    0A." with both Chg and Inv lights blinking green.  Outside the inv/charger is flashing a slow green and then quick green blinks....not in any particular pattern.  When the power is plugged in I hear a ''thunk" like the transfer switch...can't tell for sure.
 

Any suggestions appreciated.

 

Additional information.  The Power Control System shows normal voltage on both Line 1 and Line 2.  I verified that by checking various outlets around the coach, Line 1's voltage jumped all around...thus accounting for the various speeds of the box fan....Line 2's voltage was normal.  So there appears to be some type of disconnect between Line 1's gauges and the outlets.

Edited August 23, 2021 by five

[hermanmullins]

Sounds like, to quote a few, a bad or loose ground. Finding is another thing. 

Herman 

[richard5933]

Couple of thoughts...

Sounds like your inverter recognized a problem with the incoming AC power and tried to take over, and then the DC battery voltage dropped too low.

The other things you're describing really sound like your transfer switch got stuck between and betwixt. Have you got the skill/knowledge/tools to pop the lid on the transfer switch and check the incoming voltage and the outgoing voltage? While the lid is off, carefully inspect for any signs of burned or damaged insulation or contacts, as well as for anything which is loose. A loose neutral can cause all sorts of problems. Same for the hot leads, but those are usually limited to one leg or the other.

[manholt]

Five, its early and I'm on my first cup off coffee!  Please enlighten me, what is "M/W?"

[tcolburn]

Microwave?

[five]

Yes, microwave.

[five]

Talked at length to two Magnum techs today.  They aren't sure but think it has a bad FET board.  I did learn you can get rid of the fault light on the Magnum by pushing and holding the inv/chg's power button for at least 15 seconds.  Since this turned the fault light off, I turned everything back on, and plugged it into shore power.  I'll see what it says in the AM.  The tech said the FET board is around $740 and does not recommend installing it myself.  He said his diagnosis in not 100% certain, and if they sent me a part it would be a $740 gamble.  So, if I need an FET board I can either remove the inv/chg and send it to them, or drive the coach to the nearest repair facility.  I have removed it and shipped it once before....and I'm not doing that again!

One response to this question said to consider getting a new inverter/charger:  

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=MS+2812+Inverter%2Fcharger&_sacat=0

Edited August 24, 2021 by five

[rayin]

Before spending money, remove all 120VAC power sources, then open your ATS and tighten all electrical screw connections. Then do the same with your main breaker panel. If that doesn't solve anything, you only lost time and effort, but you then know they are tight. Things loosen in these rolling earthquakes on our wonderfully smooth roads.

Edited August 24, 2021 by rayin

[five]

Thanks, one of the first things I did was tighten everything.  With a bit more research and help from a third tech at Magnum, it appears our hot weather has played a part in this.  The third tech said to turn on a fan or two directly on the inv/charger.  Did that and it has worked fine ever since.  This coach has a sensor that detects too high/low temps.  Here's the fault I got on the Magnum:

FET Overload - This fault message indicates the inverter/charger has

shut down because the internal FET's (Field Effect Transistor's) have quickly

exceeded a safe operating temperature. 

[rayin]

Thanks for the information, now I know what to do If my Xantrex RS2000 begins acting weird.

[five]

The sensor has it's own small wire that is on a positive post in the battery compartment.  Here's what it looks like, BTS means Battery Temperature Sensor:

Magnum Energy ME-BTS-25 | 

https://www.fisheriessupply.com/magnum-energy...

"This is a must-have accessory for any Magnum Energy inverter/charger installation if you want to be assured that your batteries get 100% fully charged. The temperature sensor provides the inverter with precise battery temperature information so it can automatically adjust the ABSORB and FLOAT charge voltage set-points – making sure the batteries are not under- or over-charged based on the battery's temperature.
This is particularly important in assuring the batteries get correctly charged under harsh winter and summer temperature conditions.

Edited August 28, 2021 by five