A/C wiring question: Inverter

I'm confused.  I would like to add an inverter, mostly to power refrig and outlets  Obviously, not interested in air conditioners and really not microwave either.  The one I'm looking at is charger and inverter with builtin transfer switch.  I'm thinking of just replacing existing converter with the inverter/charger, since its convenient and the 12V wires are right there. 
I'm confused about the power management system on this coach and how the A/C wiring is configured.  Apparently, there are several wires from the genset/shorepower transfer switch.  Apparently there is an A/C wire from coach transfer switch directly to the rear air conditioning breaker on load panel, powering it directly.  Another one to main breaker on load panel.  Converter and refrig outlets seem to be on one breaker.  The Powerline energy management system (EMS) is supposed to cut off loads if total usage exceeds the limit of a selectable 50a, 30a or 20a.  From the diagram, it looks like the EMS is sensing all current that goes through the "Main" breaker, but not including the rear air conditioner.  My powerline display lists rear air conditioner compressor, rear air conditioner fan, and refrigerator; assuming these are the loads that it purports to control.  From the wiring diagram, however, it appears that only the refrig and converter are controlled.
So, would this work?  If I add an inverter, the DC wiring is direct to battery, the A/C in could come from the main input from the coach transfer switch and out go back to main breaker.  Ignor the converter outlet.  The rear air conditioner appears to be controlled by coach transfer switch, only if there is genset or shore power, so ignor that also.  The front air conditioner is apparently on the "main" breaker, so that would need to be shut off, either manually or via relay.  Same with the microwave.
Am I missing something?  Is there an easier way to install the inverter?  I don't think I can just plug the A/C input into the converter outlet, since it would be limited to the 15a converter breaker and the refrig is on that same circuit.  Plugging the A/C output into the converter outlet would bypass the breaker, which would be bad.  I don't want to install a subpanel if I can avoid it.
Also, why is the powerline labeled with the rear air conditioner, when the ems does not appear to be controlling that load?  And why isn't the powerline controlling the front air conditioner?  Or is it and I'm just reading it wrong?

Is yours a 30A shore power coach?  That is what typically has the direct power to the rear a/c from the transfer switch. And yes, in that configuration, the EMS would sense the power through the main 30A breaker, and not the rear a/c. The EMS is managing the 30A load limit, not the "extra" rear a/c power.

If its a 50A coach, I don't think you have the direct rear a/c wire. It should be powered through the regular load center and this gets included in the EMS management.  I'm not real familiar with Winnebago power wiring,though, so I could be wrong.

In a 50A coach, the EMS does no management when 50A power is present, shore or genset. It basically turns itself off when it detects 50A power.

If I understand your scheme correctly, you are basically running the entire coach through the inverter & its transfer switch. All shore and generator power passes through the inverter (comes from the main transfer switch, regardless of source), so coach power is limited by the max capability of the inverter. That's probably either 20A or 30A, depending on the inverter chosen..

The critical question is are you 30 amp or the optional 50 amp shore power?

If it's 30 amp and you're up for this challenge, you just need to remember to NOT run the A/C while in inverter mode. But once installed, my design is automatic and works beautifully.

http://www.rvforum.net/SMF_forum/index.php/topic,91264.90.html

I am indeed 30A, and the attached diagram in original post is for my 30A wiring setup.

And the design I'm considering does run the entire coach through the inverter, in series with the input from genset/shore power/coach transfer switch.  However, it looks like the rear air conditioner will bypass the inverter and only be powered by genset/shore power.  And the best way to control the front air conditioner is probably use a relay to shut it off when the inverter is on, or use a subpanel (which is what I did on my boat).  These RV A/C panels are not as easy to wire as a boat panel, so I'd like to not use a subpanel.  I don't expect the microwave to be usable with the inverter either, so might put that on a relay as well.

I've been looking at your wiring diagram and Winnebago has conveniently placed the 50 and 30 amp wiring side by side, makes it easy to compare.  If this was my rig, I would first convert to 50 amp. I think you could do this for the price of the 50 amp shore cord and a few hours of labor. The transfer switch is probably the same for either coach, the load box appears to be large enough to accommodate a breaker rearrangement, in fact it appears larger than the 50 amp load center.  The rear A/C wiring will need to be rerouted from the transfer switch to the main load center.

As far as your inverter, I would install a sub panel for those circuits you want have on inverter, this is the right way that will cause less grief in the future.  Look at some high-end diesels around the 1999-2000, they probably had inverters as a standard feature - use Winnie's inverter diagram for your install as much as possible.

And the design I'm considering does run the entire coach through the inverter, in series with the input from genset/shore power/coach transfer switch.

Click to expand...

OK, you can do that successfully with a 30A set-up like that, but you MUST use an inverter rated for 30A so that it can pass through 30A power when shore or genset is active. If not, it's own internal breaker would trip as soon as you exceed 15A on the input.

The inverter I'm considering has a 30A built-in transfer switch.  Its the xantrex freedom 1000.  The charger is a little anemic at 20A, but its 3 stage and MSW for about $350.  .  On the boat I had good luck with MSW.  Thanks John.  Considering the 50A changeover.  Shouldn't be too hard I wouldn't think.  Except perhaps for the Load management system (EMS).  A second panel would be an issue as well.  The refrig has been swapped out with a bad job by PO.  So I had to shore up the framing and leaving no room for a subpanel under the refrig.  Might have to remove the entire thing and re-do the refrig first.  Its like a boat "Can't Do This Until you do That".  CDTUDT
Trying to figure the main advantage of 50A and it appears to be the ability to run everything at once without popping outside breakers. 

The 30 amp Load Center can be converted to 50 amp.

Bob Hatch 30 to 50 amp conversion
http://www.bobhatch.com/electricStuff/30to50amp.htm

I have to ask to be clear on exactly what you are trying to accomplish here.  Are you switching your fridge over to a 115v AC type? what do you have for House batteries, ie how many and how do you plan on charging them?  If your fridge is not an AC only (home) type then why bother with having AC to it supplied by and inverter they are actually work better off 12vdc and propane.  As far as the AC outlets, which ones do you want to power from the battery?  Check the wiring diagrams and see if they are all wired from the same breaker and then install an inverter down stream of the breaker. Make sure this inverter has it's own built in circuit to keep sense battery voltage and 115vac.  But remember when running the inverter you will be pulling down the house batteries. So if you are boondocking be prepared.

Thanks.  Always good to clearly establish objectives before beginning a project.  PO had replaced the propane/12V refrig with a 115V household type.  So, to run the refrig, we have to have 115V AC.  That means it doesn't run under way or when boondocking.  We don't boondock often, but occasionally when just going from point A to B, we stop at Walmarts or rest stops or occasionally parks w/o power.  Would love to have the capability of running refrig under way and without A/C connected at site and without running the genset.  House batteries are limited.  two type 31 discharge-type lead acid.  Having trouble finding out exact power requirements of this refrig.  But it appears to be approximately 1kwh per day of use, or average 4 amps at 12v for each hour run (which takes into consideration duty cycle).  So I would have to put 4 amps back into the house batteries continuously to avoid drawing them down.  It doesn't look to me like the F53 alternator is very strong.  Since we have a 45 amp charger, we would have to run the genset one hour every 10 to keep the batteries charged (just for the refrig load).
This is not looking good.  So for everyone who advocates replacing the 12v/propane refrig with a household type, how do you handle this?  Is my math wrong?  On our previous TT, the dometic worked fine.  One minor repair over 3 years.  On my boat, had 1000AH in 5 4-D batteries.  And 250W solar, and wind generator that often produced 20A, and 100amp alternator on engine.  And a backup gas 2KW gas generator for emergencies.  And we often were anchored off the grid for months.    SOunds like the motorhome needs more battery capacity at a minimum.  Maybe better F53 alternator.
So back to the inverter question:  would like to power refrig and a couple 115V outlets, for small things like charging small battery-powered devices.  And perhaps for flat screen TV.  Can MSW power a TV?

If the fridge pulls 4 amps using 120 volt a/c, you will have to multiply that amp draw by to to get the amps needed supplying it through an inverter from the batteries. Also you probably will use 10-15% more power due to losses from the conversion.

The F53 alternator should be plenty to keep up with battery charging needs while driving during the day. During the nighttime, with the headlights and such on, maybe not. Do you know what size it is? I'm guessing 95A (that's what is being offered as a replacement alternator, anyway).

Yes, your particular motorhome battery bank isn't sized for much off-grid time if you use much more than lighting and an LP fridge and water heater. Even the furnace fan will tax it severely. More and/or larger batteries are a good upgrade if you have room.  Other brands/model of coaches often have more battery capacity to begin with, but that would be at the higher end. Your boat clearly was not an "entry level" model - it was very well-equipped electrically!

So, 1 kwh is indeed an average of 4A @ 12v and that is what you need to replace each day. A bigger charger might help a little, but batteries won't accept the full charger output for more than a short period anyway, so most charging takes place at less than 40A.

I guess I don't see the problem with just overnight stays. You run the genset awhile in the evening, and again in the morning. Then the next day of driving should bring everything up to 100% again.

Oh yes, a modified sine inverter can run tvs with no problem. I have a 2500 watt MSW inverter and it does the tvs, computers, microwave, etc, just fine.

Thanks Gary.  BTW I'm just east of Tampa, so not that far from Ocala.  How do I tell what capacity the F53 alternator is?

There should be a Ford part number on it. Or inquire at a Ford dealer parts counter (if they are the friendly, helpful sort). I just looked up 1999 F53 alternator online and see that the Ford replacements being offered are 95 amp.

You might find a 99 F53 chassis spec online if you Google it. I've found other years, e.g. 2004, but haven't looked as far back as 99.

The brochure for my Brave states that the alternator is 130 amps. This should provide sufficient power for vehicle and coach operations including a reasonable sized inverter
So does the 1999 adventurer.

With two or three house batteries, you aren't going to have much off-grid or off-gen capability even with solar.  On our cruising sailboat we had a 4D and an 8D gel bank, gen set, solar panel and a wind generator.  We were good to go because of the battery bank capacity.

The 1999 F-53 alternator is a 130 amp per the brochure

1999 Adventurer
http://winnebagoind.com/resources/brochure/1999/99-Adventurer-bro.pdf