Electrical Problem: Magnum 2812

[five]

For a couple of months, I've been getting a red fault light and an "AC Overload" message in the Magnum remote...Magnum is a 2812.  Very seldom at first, then quite often.  Made numerous calls to the Magnum tech line, reset it many times.  Finally, it happened right after being reset and just after I talked to Magnum.  I called back immediately. 

 

After many tests, the tech said to disconnect from shore power and send the Magnum to a repair center.  I hooked the coach up to a trickle charger and sent the Magnum off to a repair facility.  Shortly thereafter got a call that the Magnum was fine and there is a short somewhere in the electrical system in the coach.  I do lots of maintenance and repairs on this thing, but I don't think I want to tackle a serious electrical issue.  I'm looking for suggestions as to what I can check (not too complicated) and suggestions I can give to an RV shop as to what they can look for and check.  Coach is a 14 American Eagle.

 

Thanks

[wolfe10]

You are the best judge of what your skill and interest level is-- as long as you are safe working around 120/240 VAC!

Is your inverter output wired through a sub-panel?  If so, turn off it's main breaker and all individual breakers.  Start turning them on one at a time. An ammeter will tell you what is happening.  If you don't have an ammeter to check current draw, do this test with shore power off/generator off.  In other words, your battery is powering your inverter. Watch your amp draw/voltage on your inverter remote panel (assume you do have one).  Let us know if any circuit causes a high amp draw from the battery with all appliances supplied by the sub-panel off.  Then turn them on one at a time.  See if any show excessive draw compared with that appliance's specs.

[five]

No sure what a "sub panel" is... inverter and charger each have separate breakers.  I do have an ammeter, although unsure as to how I would use it to check current on each line.  Therefore, since I have a normal Magnum remote panel, seems it would be easier to check using it.  I'll be off line for around a week, I'll keep you posted.

 

Thanks for the help.

[wolfe10]

Let's clarify "sub-panel". It is the preferred way (not least expensive) to wire an inverter/charger.

There is an inverter breaker on the main 120 VAC breaker panel.  Call that "120 VAC IN".

Then 120 VAC output from the inverter/charger (yes, assuming yours is both-- therefore an inverter/charger) then goes to the sub-panel.  The main breaker on that panel is the "IN from the inverter/charger.  Then, each circuit that can be powered from the inverter has a breaker on that sub-panel.

 

The other alternative is that the inverter/charger 120 VAC output just goes through breakers on the inverter/charger and then directly to circuits it powers. American coach can give you details on how yours is wired.

[dickandlois]

Five, When you get back on line, could you post the Make Model and Year of your coach?

The Shore power wiring has gone through a number of changes over the years.

Do you have the system manual for you Charger/Inverter?

Rich.

[five]

Yes, I have the manual.  Coach is listed in OP...2014 American Eagle 45 T.  Also, the configuration is eight 6 V AGMs for the coach, and two 12 V AGM for the chassis.  Many coaches of this model have two inverter/chargers (one for each set of four batteries, and one dedicated to the residential refer), my coach has only one inverter/charger.

Be off line tomorrow for a week or so.  Thanks.

[dickandlois]

12 hours ago, FIVE said:

Yes, I have the manual.  Coach is listed in OP...2014 American Eagle 45 T.  Also, the configuration is eight 6 V AGMs for the coach, and two 12 V AGM for the chassis.  Many coaches of this model have two inverter/chargers (one for each set of four batteries, and one dedicated to the residential refer), my coach has only one inverter/charger.

Be off line tomorrow for a week or so.  Thanks.

Thanks,  if I'm reading you posts correctly. Having 2 inverters stacked to supply 240 volts is not standard. 

Does the problem happen on shore power and generator power?  Kind of sounds like a common neutral issue / loose connection and  inverter with a loose connection(s) at the inverter point or at main or sub panel. The problem happened more often over time,-sounds like a connection getting looser over time. But the inverter was R and R for testing at Magnum power service, so the line in and out connections should now be tight. But one might want to check the chassis end of the large ground wire running between the inverter and the point it connects to the chassis.

REMEMBER never work on the connections with at the main and sub breaker panels or inverters powered on !!!

With no AC supplied from shore power or generator and the inverters turned off. Check the resistance between both inverters neutrals, the input side an output side and the ground pin of the 50 amp connection of the shore power. They should both read open. The coach is not grounded until you are connected to shore power.

Rich.

 

 

[kaypsmith]

Two 120 volt inverters does not become a 240 volt circuit, still 120 volt circuits twice.

[manholt]

I have the 2 inverters!  Magnum.  Think FIVE had it also on his previous coach...also an American Coach.  I'm just wondering if his thermostat fuse is good?  There should be one for each AC, behind the panel. 

Carl 

[rsbilledwards]

He says he has only one inverter, but that many have two.

Bill

[five]

First a bit of clarification on some earlier comments.

 

Rich...most AC coaches like mine have two inverters and two banks of four 6 v batteries each.  They are wired separately with one inv/battery bank solely for the residential refer, the other inv/battery bank for all other 12 v requirements.  My set up is only one inverter charger but eight 6 v batteries to run everything.  Your analysis was pretty much right on target.

 

Bill...read the above paragraph.

 

As Paul Harvey would say, here's "the rest of the story:"

 

The repair facility sent it back and I reinstalled it.  While installing it, I noticed a long very heavy duty copper wire coming from the battery bank, behind the wall to underneath the Magnum.  I looked in my Magnum paper work...not the operator's manual, the installation manual.  I noticed a lug/bolt on the right side rear corner on the bottom of the Magnum as sitting in the coach.  Called Magnum and the AC tech line, both said that's where a ground goes.  I secured the copper wire to the lug/bolt, rechecked all connections, turned on shore power and only the charger and inverter circuit breakers.  All looked normal on the Magnum remote in the coach.  After a few days, I turned on all the other circuit breakers, all still normal.  Turned off the power, turned on the inverter and ran the microwave off the inverter, all still normal.  Turned shore power back on, all still normal...float charging.  Two days later I unplugged from shore power and took the coach out for a 20 mile run and to refuel it.  When I parked it the Magnum remote again indicated all was normal, it was float charging.  I've put off writing this to be sure all is well, apparently it is.  The copper wire noted was not in the grounding lug/bolt originally.  I don't know if it was grounded 'enough' to be functional up until it started acting weird in April... then getting progressively worse.

 

I violated one of my cardinal rules going through this drill.  This is RV number six for us.  When there is some kind of problem, I always (not  this time, though) check the simplest and easiest to fix aspects of the problem first.  This time, I was talking to the "experts" and did not even think about doing the easiest thing first...check the security of all wires and grounds.

 

Thanks to those who made suggestions.

 

[dickandlois]

Five, Thanks for the update! Kind of thinking you analysis of the issues is correct! Kind of sounds like the ground wire got pinched tight enough to ground the inverter through the mounting bolts and vibration slowly weakened the once capable connection.

You mentioned 2 charger /inverters one for each battery bank. There are some very good battery chargers on the market, that would keep the second bank of batteries charged is all 3 states of charge and also cover Wet, AGM and Gel specifications for less money and weight.

Is the second inverter setup to be a backup for the refrigerator, should the other one fail?

The little items can run everybody in circles at times. LOL-BTDT !

Rich. 

[rsbilledwards]

Five,

I am not sure why, as I pointed out that you had only one Inverter. ??? Not quite sure what you mean?? Glad you solved the problem.

 

Bill Edwards

[dickandlois]

59 minutes ago, rsbilledwards said:

Five,

I am not sure why, as I pointed out that you had only one Inverter. ??? Not quite sure what you mean?? Glad you solved the problem.

 

Bill Edwards

Bill, My mixed up question regarding the inverter set up on Five's coach. Rich. Been to hot for coffee and I do not drink much soda. Caffeine withdrawal  

     I,m real slow sometimes and needed to reread Fives update to finally have that Ah Ha moment. Got stuck on the two battery banks-One for the Refrigerator and one for the 12 volt requirements. ALL of the 6 volt battery banks charged from one charger. Just getting old. Anyway think I'm now clear headed again ?  So the one charger is set to charge 880 Amp Hrs. of batteries and one 440 Amp set is just to power the inverter and the other to supply DC loads.

Rich.

[manholt]

Rich.  Since I have 8 AGM's being installed today by NAPA, after they arrive.  I want to make sure that they have the same Ah as the current acid batteries that I have now.  My question after reading this post 3X already, and it seems to correlate with my Blinking light post.

Where do you come up with 880 Ah (Amp Hrs.)?  And 440Ah?  I have 2 Magnum 2812 Inverter/charger at 928Ah each, or 232Ah per battery!  All 8 are Interstate Extreme GC2-XHD-UT, 122 mins @ 75A, 232Ah.

Would like some clarification ! 

[hermanmullins]

When determining the total Amp Hours do you just add the A/H of each battery together to get the total? (100 a/h per bat. X 4 bat. = 400 a/h?)

Herman 

[manholt]

I guess.  I'm also guessing that the important part is how many minutes you have at 75A per battery, per 2800 PSW inverter/charger...that's what I'm asking!

[kaypsmith]

When using 6 volt batteries to run a 12 volt system, two six volt in series to make 12 volts, two 100 amp six volts = 100 amps 12 volt. If using 4 6v batteries, then 200 amps @ 12 volts.

Carl, with 8 232 amp hrs 6 VDC batteries, each pair of 6 volt batteries wired in series to give 12 volts and then each of those pairs wired in series; that gives you the equivalent of 4 232 amp hr 12 volt batteries or 928 amp hrs @ 12 VDC.

[manholt]

So, that would give me 464Ah per Invertor/charger?

[wolfe10]

Carl,

Yes, if the 8 batteries are divided in two 4 battery banks, one bank to each inverter, your total amp-hr per bank/per inverter is 464 amp-hrs@12 VDC.

Of course, for best battery life, you don't want to discharge below 50%.  So that gives you a usable amount of about 232 amp-hrs @12 VDC per inverter.

[five]

A final clarification.  Most AC coaches like mine have two inverter/chargers and two banks of four 6 v batteries each.  They are wired totally separately with one inv/battery bank dedicated solely for the residential refer, the other inv/battery bank for all other 12 v requirements.  My set up is only one inverter charger but eight 6 v batteries to run everything.  I do not know why the original owner wanted eight batteries and only one inverter, but that's what I have.  These residential refers draw so little power, four 6 v batteries would have been plenty.  In fact, one of the guys in our club just went from four 6 v batteries to two 12 v batteries.

[kaypsmith]

Five, my question would be, how many watts output at 120 volts is your inverter/charger? If others are interested, I have a 5000 watt PSW inverter/charger that actually is a 240 volt output inverter, that requires 24 volt battery bank. The unit requires 240 volt input to enter the auto charge stage, which in turn charges the 24 volt battery bank. Also in the setup, I have a gasoline run 24 volt generator that also starts automatically which is set to auto start at 65% charge of the battery bank. This little unit runs super quite because it runs as slow as 800 to 2400 rpm. Since my coach is 24 volt system, I can run the chassis batteries right along with the 6 2000 amp gell cell batteries to keep the system charged from the 230 amp 24 volt onboard alternator of the coach. This gives the ability to run two roof airs at the same time along with res. fridge and other amenities while traveling. Just a little FYI for anyone wondering.

[manholt]

Brett, FIVE and Kay.  Thank you.  I also owe a TY to Bill E. and Joe.  It now makes sense to me, because I can picture the set up in my mind.  I know that I have a 2,800 PSW, so I assume (I hate that word) that each Inverter/charger is 1,400 PSW.  I will check that out, like FIVE I have the step by step installation manual....did not make much sense until now!

Kay.  The 24V gas generator, is that the only generator you have?  Your coach is 40' & no slide outs?  Or did you modify and add slide's?

[kaypsmith]

Carl, no slides, actual length 41.5. I would think that yours is probably 2000 + 800 if I were to guess but that may be wrong. Does your panel show charge from one inverter/charger, or two? If I were a betting man, I would bet only one with a charge circuit for all three battery banks using isolation circuitry. And to answer the 24 v gas, no, I also have a 6000 watt propane Honda generator. I use three ATS's in the set up.

[manholt]

2 separate inverter/chargers, both charge 4 house batteries and one also does engine when on inverter and 50A HU or 20A in garage!  Both have charge on/off and inverter on/off.

When coach is stored and on 20A, I shut everything off except refrigerator, then put one on inverter and 5A charge and one on 5A charge.  That's why it's a mystery to me, why so much battery for Fridge? 

Run a Onan Diesel 10KW gen.  150 fuel.