Power a coach with 2 - 4000 watt inverters

[wayne]

I am gettitng ready to start the layout for the power in my coach. I purchased the Electrical Design Layout book by Goerge Myers to get some basic ideas. He suggests using an inverter to run some dedicated circuits on the coach and a generator to run the rest with seperate panels for each.

As I continue searching for ideas I have noticed that the larger conversion companies such as Marathon, Parliamont, Liberty are using 2 - 4000 watt inverters to power the entire coach and the generator to charge the batteries when they fall below 12 volts.

It seems like a pretty involved system but I have noticed this setup on some older coaches (1999 ) and haven't heard anything negative.

I have a 24 volt, 270 amp alternator with 2 - 8D batteries. I do not have the factory bus a/c.  I realize in order to do something like this I would have to add batteries but don't know how many.

Any thoughts?

[belfert]

The dual inverters may be for 240 volts for a electric only coach. 

I plan on two electrical panels with one for inverter unless I can figure something else out.

Brian Elfert

[TomC]

I saw that set up and the owner of the bus used 8-8D Lifeline AGM batteries.  That works out to be 1240lb of batteries!  Personally, I'd use 2-8D Lifeline AGM and a 2500 watt inverter (what I have on my bus).  Anything above that, use the generator.  If you use air bag mounts and mount the generator in the cargo compartment in its' own sound proof enclosure, you can make it just about silent running.  Since you'll probably have a 10-12kw gen in it anyway, you can buy alot of Diesel fuel for the cost of the 2-4000 watt inverters and the extra batteries it takes to run it-not to mention the extra weight you have to haul around.  Good Luck, TomC

[belfert]

How do you soundproof a generator and still get enough air to cool it?  Is your radiator remote mounted?

Brian Elfert

[Ross]

How do you soundproof a generator and still get enough air to cool it?  Is your radiator remote mounted?

Brian Elfert

Some great sound proofing material is old truck bed mats.  These are about 1/4-3/8" thick and solid, dense rubber.  While I was helping my RV parts dealer friend get ready for his auction I found a few of them.  I also found some lead lined foam sound deadening blankets. 

[Jerry Liebler]

Wayne,
     Two SW4024's allows 240 volt stuff both underway and on a 30 amp 120 shore cord, but if you have no 240 volt needs it's overkill.
You can only get 5000 or so watts from the coach alternator to run AC underway so a single SW4024 is a good choice.  If you use the SW4024, there is no reason for seperate panels simply run everything through the inverter as it can pass 60 amps (this avoids the tough choices of what the inverter powers).  If your loads total 7,500 watts or less and are all 120 one SW4024 works very well, especially with a 7.5kw generator and a 50 amp shore cord.   I strongly recommend the SW4024 because if its unique ability to limit shore cord draw while delivering additional power from the batterys and automatically starting the generator if the batteries get depleted.
Regards
Jerry 4107 1120 

[FloridaCliff]

Wayne,

I am with Tom on the fact that it would take a long time to recapture the investment in two 4000 watt inverters and the batteries as compared to running your genset when you have a real power demand.

Also, that power is coming from somewhere. If your on the inverter you are creating a load on the alternator, which is loading the engine.  No free lunch!

I opted not to run completely seperate circuits for my inverter.  Two reasons; first, I didn't want to limit my inverter to certain outlets and did't want to run two seperate systems and second, my demands change.  If its hot or cold I am running the genset for the a/c's and use that power for my other loads or if no a/c's I run the small loads just off the inverter without having to move individual items plugs..

It really depends on how you are going to use the coach and what kind of loads you will have.

Brian,

Besides the sound deading insulation, I have seen several enclosed gensets with the air inputs and exits with multiple 90's to cause the sound waves to be trapped in the box.  I am sure there is some one on here who has first hand experience with these.

Cliff

[wayne]

Jerry
I like the thought of running everything through 1 SW4024 with a 8kw gen if that would meet my power requirements. I plan on running 2 roof top a/c units maybe 3. Would I need to add more than the 2 - 8D bus batteries?

[Nick Badame Refrig/ACC]

Wayne,

The only problem with 1 4024 is your only gona have one leg powered by the inverter. that's the way the 4024 is designed.

Thats why they install 2- 4024s, to optomize both legs of 50amps, just like your shore power.

I agree with Tom also, to run everything through your inverter. you will have the choice what to power up.

The A/C issue, either run your gen set, or install a automotive A/C compressor on your engine. thats the most cost effictive, and efficient way.

Even running 2 roof tops or 2 conventional A/Cs while under way is not enough tonnage to keep the coach properly cool.

Just for your info, A standard Car A/C system is equil to a 5 ton house A/C system! Two RV A/C will only total up to 2 1/2 tons!!!

So think about what would addiquitly cool your coach, do the math! The original coach air is 11 tons.

Hope this helps-
Nick-

[Melbo]

Nick

Not trying to throw bombs or wood on the fire of something like that but as a practical matter do you really want to cool your coach "properly" while going down the road. I mean in my WORST nightmare I would have my girlfriend still sleeping in the bedroom in the back of the coach and wanting to have AC and my mistress taking a hot shower in the middle of the bus trying to steam my girlfriend out. I would be driving while my mom is cooking breakfast right behind me and we would be heading into the sun. I really don't care what happens behind the driver as long as I am cool I am happy. We can let the women fight it out in the back. I think I would make sure that there is AC in the front of the coach that can be directed to make the operator comfortable. After that let fans do what they can with roof top vents etc. and when we park for the night we can all get in the hot tub and relax with a very tall cold drink. Just my thoughts.

Melbo

[Jerry Liebler]

Wayne,
      Yes you'd want a house bank of some kind, it could be 2 more 8ds or 4 golf cart batteries or much more depending on what you want to run for how long. This is to make sure you can still start the bus.  If you choose efficient air conditioners you should be able to run 2 from the bus alternator.  If you find air conditioners that draw under 10 amps each you may be able to run 3 as the SW4024 has a huge surge rating needed to get them strarted.
Regards
Jerry 4107 1120

[Nick Badame Refrig/ACC]

Melbo,

I have a reputation to live up to, I'm an A/C Man. And I have 3 kids and a wife who dosn't like to be married to an A/C guy AND SWEAT!

Anyway, I'm kind of a happy guy when my passengers are happy too!

Why do I want the whole coach Cool?   Because I can!!

Nick-

[Jerry Liebler]

Nick,
       A 50 amp shore cord will supply 6000 watts on one leg, a 7500 watt generator will supply 7500 watts or 62.5 amps on one leg.  The SW4024 can pass 60 amps of 120 volts. There is no need to balance loads between legs if the loads fall within these limits.
Regards
Jerry 4107 1120

[Nick Badame Refrig/ACC]

Jerry,

Your correct!  But is that proper?

I'm all electric, and I don't rely on any campground's  50 amp service on a hot july weekend to be able to supply 50 amps on 1 leg without the voltage dropping

below 100 volts. It happened this past saturday in O.C. Maryland. And it was only 80 deg. ouyside! My RS 3000 Xantrax, Set off a warning fault of low voltage,

And sure enough, 97 volts on my UIE hand held Volt Meter! Same as the RS 3000 displayed!

Nick-

[Jerry Liebler]

Nick,
     There is nothing incorrect about drawing 50 amps of 120 volt power from a 50 amp 120/240 circuit.  If you encounter that kind of voltage drop the campground's wiring is 'p--- poor' and you should have complained.
Regards
Jerry 4107 1120