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Author Topic: Mini-split update  (Read 2836 times)
Tikvah
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« on: January 07, 2014, 05:45:01 AM »

I finished the mini-split install yesterday.  Turned it on and we have been totally amazed at how much air it moves almost silently.  Even the outside unit is almost impossible to hear standing next to it.  We're impressed!

Then the test.  Here in central Florida we woke to 27 degrees this morning.  Great night to test the heat side of the unit.  I couldn't believe how warm we were during the night.  It easily maintained 74 degrees all night.  The heat was even and comfortable.  The next test will be the next wave of hot weather.

Now my question.  We had 25% humidity during the night.  That's pretty good in a land that is always humid.  But we still have terrible condensation from our windows and roof vents.  This condensation is going to rot my wood and rust my steel if we can't get it controlled.  Any ideas?  We spend our mornings (when it's cold) moving around the coach sopping up water.  This isn't good.  I figured 25% was good but it isn't.  What do I do?  Will a dehumidifier work? 

Dave
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« Reply #1 on: January 07, 2014, 06:07:55 AM »

They don't dehumidify in the heating mode a dehumidifier is the only choice you have or a rain coat @ 34 degrees with 80% humidity that is why a defroster on automobiles has the AC tied into the heat fwiw
« Last Edit: January 07, 2014, 07:17:59 AM by luvrbus » Logged

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Dave5Cs
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« Reply #2 on: January 07, 2014, 06:14:54 AM »

Dave try opening a vent and or slightly open a window. Should help get rid of some of it.

Dave5Cs from Galaxy S III
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« Reply #3 on: January 07, 2014, 07:01:51 AM »

  Dave try opening a vent and or slightly open a window. Should help get rid of some of it.      Dave5Cs from Galaxy S III   

     Right, and everyone knows that hot air rises but not a lot of people know that water vapor is about 70% the density of air (at the same temperature).  So, moisture rises, too*.  Open the highest vent you can -- but be aware, if you have a vent open enough to move a lot of moisture out, you lose a lot of your $$heat$$, too.

(*  OK, it's not really quite that simple in real life since you have a mixture of air and water vapor in any artifically heated volume but it makes a difference and the principle is correct.)
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Bruce H; Wallace (near Wilmington) NC
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« Reply #4 on: January 07, 2014, 08:29:36 AM »

Dave, the best investment that I made was buying a small 110v dehumidifier.  You can catch them on sale at Lowes or other box store.   I run it 24/7.   It is amazing how it changes and maintains the humidity level that you set it to.   
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« Reply #5 on: January 07, 2014, 09:08:15 AM »

Get the kind that has a hose connection for discharge, that way you can let it drain directly outside.

Brian
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« Reply #6 on: January 07, 2014, 10:07:46 AM »

Most of the larger units have the hose drain hook up.   I never has used it.  I have the larger unit, with 2 gallons of capacity.  It will run 3 days before it shuts off at the high level limit and that's in the rainy Pacific NW..    Basically, they are closed loop mini heat pumps.   You do net out some heat out in the process.
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« Reply #7 on: January 07, 2014, 01:56:20 PM »

First Ac day close your bus up tight and run the unit around 62(lowest setting ) if I remember rite.  dry it out once.. Might help in future..You  will be surprised how well they draw moisture out.. If you are the type that can't do that.. the part of Florida your in is up and down this time of year .  Fires one week--floods the next..Fire season coming up if I remember correctly--then more rain about 3 months later. 
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« Reply #8 on: January 07, 2014, 03:29:48 PM »

Dave,
What make and model is your mini-split?   How much power does it take to start and run it?

John
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« Reply #9 on: January 07, 2014, 05:18:15 PM »

http://www.minisplitshop.com/store/product.php?productid=261&cat=0&page=1

Right now I can't imagine building a bus with anything other than a mini-split.  We are set to install a second one, but not sure if we will need it or not.

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« Reply #10 on: January 07, 2014, 05:52:25 PM »

http://www.minisplitshop.com/store/product.php?productid=261&cat=0&page=1

Right now I can't imagine building a bus with anything other than a mini-split.  We are set to install a second one, but not sure if we will need it or not.


I had a very negative purchase experience with this website.  I bought three units from them (also Soleus), and when one had a dead screen upon installation, they will not return any of my calls or e-mails.  I would NOT do any kind of business with them again.  Just a heads-up for anyone else thinking about taking the mini-split plunge.

The unit still fundamentally works, but the temperature readout does not work at all. 

Cheers, John
« Last Edit: January 07, 2014, 05:56:19 PM by dukegrad98 » Logged
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« Reply #11 on: January 07, 2014, 07:34:23 PM »

Right now I can't imagine building a bus with anything other than a mini-split.  We are set to install a second one, but not sure if we will need it or not.

We also put in miniplits: Two of them. (See details in our bus build thread here: http://www.busconversions.com/bbs/index.php?topic=22081.0

In my humble opinion, you might do great with just one minisplit if:
   1. It is just you and your spouse traveling (more people = more heat generated)
   2. You don't frequent places with temps above 100.
   3. Your bus is well-insulated.  

My two pesos' worth.
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« Reply #12 on: January 07, 2014, 07:38:45 PM »

  ...Right now I can't imagine building a bus with anything other than a mini-split.  ... 

    I was looking at the 12K BTU unit but at a price of $499 for the 9K, it's hard to beat.  I'm sorry to hear about "DukeGrad"'s experience, tho; that's worrying.
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Bruce H; Wallace (near Wilmington) NC
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« Reply #13 on: January 07, 2014, 07:42:27 PM »

  ...  In my humble opinion, you might do great with just one minisplit if:
   1. It is just you and your spouse traveling (more people = more heat generated) ... 

      Or if your bus-house is a single story!   
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Bruce H; Wallace (near Wilmington) NC
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« Reply #14 on: January 07, 2014, 08:22:52 PM »

      Or if your bus-house is a single story!   

Ahhh yes. I believe only two buses on these forums are multi-story single family dwellings. And Mine might be one of only a few with a basement bedroom.

 Grin
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« Reply #15 on: January 08, 2014, 04:18:58 AM »

You guys are kidding aren't you to think 9000 btu or even 18,000 btu is going to keep a bus cool going down the road you can insulate all you want too but not a thing one can do about the glass and BTU's are BTU's no matter what unit it comes from

 Nothing can beat a automotive type AC when traveling no way can one replace a 30,000 + btu dash air with 18,000 btu AC it's not going to happen IMO

good luck
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« Reply #16 on: January 08, 2014, 06:05:25 AM »

   You guys are kidding aren't you to think 9000 btu or even 18,000 btu is going to keep a bus cool going down the road you can insulate all you want too but not a thing one can do about the glass and BTU's are BTU's no matter what unit it comes from

 Nothing can beat a automotive type AC when traveling no way can one replace a 30,000 + btu dash air with 18,000 btu AC it's not going to happen IMO

good luck 

    Yeah, I think that's right.   My plan is a dash air off the engine (combined with cab heat and defrost) "rolling" with a pair of mini-splits for parked.  It's gonna be expensive but what isn't on these things?Huh
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« Reply #17 on: January 08, 2014, 06:31:32 AM »

Presently have 3  mini-split  plus prevost drivers air.  Also can close off 1/2 of coach if needed..  It was a high in single digit and they worked Monday.  Fwiw   Still Testing for final opinion...I have installed in my home and cut elect bills by 60%  for HVAC  from  heatpumps.    Bob
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« Reply #18 on: January 08, 2014, 06:48:38 AM »

   Presently have 3  mini-split  plus prevost drivers air.  Also can close off 1/2 of coach if needed..  It was a high in single digit and they worked Monday. ... 

     Do your mini-splits have a heating coil or is the heating done like a heat pump, Bob.  Glad to hear that they're working well for you.   BH  NC  USA
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Bruce H; Wallace (near Wilmington) NC
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« Reply #19 on: January 08, 2014, 08:28:28 AM »

Mini split are inverter type  heat and ac  also have  aux hot water heat off engine.. did not retain main heating system on bus.  If the mini fail and engine heat fail and box heat fails then I'm in the wrong place AND NEED A MOTEL.  Life choices..
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« Reply #20 on: January 08, 2014, 04:31:02 PM »

  Mini split are inverter type  heat and ac  ... 

    Thanks, good info to know.   BH
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Bruce H; Wallace (near Wilmington) NC
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« Reply #21 on: January 08, 2014, 05:09:12 PM »

I realize that I seem short on the subject but in the past I feel that some have taken my lead as the only way to go.  I make my own choices and fail often and that is on me!  I shared my thoughts in past and feel some what --- well for someone failures.. what I assume and my decisions from ones that actually have had success and failures is that inverter type is least trouble.. vibration is your enemy..  biggest cause of failure is over tight fittings causing cracks - leaks. recharge kits are available on line for $55 and simple vacuum pumps for about $100.  Teflon paste on flares when installing helps when tightening flares fittings( I had a hvac friend) who runs them in his MCI 8 help me with my install.  I run 3 separate units instead of one condenser with 3 evaporators so if one goes down I still have 2 etc.  Just my opinion.. If I hit my foot with a Hammer  please don't try that !!   Highest seer factor you can get  mine are 16   pull  6amp at start up and running..  Total cost for all three including shipping to Indiana 1470$$  you can deal on a package.. Insulate : anchor: Check factory anchor inside cabinet: Don't over tighten fittings; Make sure you have good air flow to condensers.  Bob
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« Reply #22 on: January 09, 2014, 07:27:18 AM »

Says it has a dehumidifer in it, no?
Where did you put the outside unit?

Dave5Cs from Galaxy S III
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« Reply #23 on: January 09, 2014, 08:02:33 AM »

I agree with Bob's logic above -- multiple complete units, rather than just one compressor running a few indoor units.  That way if one goes down or springs a leak, you've at least got some redundancy and can keep going until you get repaired. 

My comments above were NOT negative as toward mini-split technology in general.  I think it's effective and works well.  In fact, a good friend of mine is using it in a 7500-foot home, with low electrical bills.  Bob already covered the potential drawbacks or failure points in mobile installation, and that's for every installer to deal with as needed.  My negative experience was purely with the salesman (Raf or Rafael or something, it's been a year or two) at the mini split shop online -- he was fine while he was selling, but vanished when support was required on the electronics in one of my units.  (Hey, it's made in China -- you have to manage your expectations and treat them as disposable...)  The units themselves perform as they should, and I would recommend them as a general matter...just from another retailer.  Felt I should post that in case it was unclear.

Cheers, John
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« Reply #24 on: January 09, 2014, 12:25:34 PM »

Says it has a dehumidifer in it, no?
Where did you put the outside unit?

Dave5Cs from Galaxy S III

Yes, it has the dehumidifier setting, and it works, however when the heat is on it does not dehumidify.  wish it would do both at the same time, but only in the cool setting or alone.

third day today and loving it!

Dave
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« Reply #25 on: January 09, 2014, 08:29:49 PM »

Ok, my 2 cents. The inverter tech is more efficient, (ramp up less amp draw) but the long term maint has high cost. I can easily fix and bypass a proprietaty (sp) control board on an AC based compressor fan system. But throw in the AC to DC control system and the $$$$ board, Computers and it is out of my control. Sort of like going from points to the computer controlled cars of today. Sorry I digress. I have 3 mini splits, and they have saved me money. I like the simple ac based systems as I can put a relay (contactor) and simple thermostat to control instead of having to pay for the high dollar $$$$$ product specific money maker they have built in. Most of my ac's run all of the time until I shut them off. this negates the savings of the inverter based designes. Oh yea, I am paying for my supposed savings on the inverter based system right now,,,, and that one system is not running. Had this been like the next 2 I installed (non inverter based) I would have them running now.
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« Reply #26 on: January 09, 2014, 10:28:58 PM »

Great thread. Where did you put the outside unit in a bay? does it have a copper line between the units?
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« Reply #27 on: January 10, 2014, 05:40:30 AM »

This mini split deal is all going to be personal preference  I have a friend with a H-45 he has 3 units he paid big bucks for the ceiling mount evaporators air handlers he mounted all 3 condensers in one bay and he has a problem getting enough air he is not going to cut holes in his baggage doors that is out of the question  

He is going to remove his to much maintenance for him he always has leaks,remote problems and board problems but this guy has almost 300 ft of copper tubing lines and he doesn't like having 3 remotes

 I just asked him a simple question why does the automotive world use hoses and aluminum piping on the AC units he laughed and maybe to prevent leaks  I think they will be fine parked with low mileage travel and not used when underway with the high pressure of the 410 freon  JMO    
« Last Edit: January 10, 2014, 05:42:11 AM by luvrbus » Logged

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« Reply #28 on: January 10, 2014, 06:54:01 AM »

I asked this on another forum.. when installing the Mini Splits ..Why can't they be connected with rubber hoses instead of all copper piping ..seems that it would remedy a lot of the vibration issues that everyone is having ,How much air circulation do the bottom units actually need?  best wishes Pete
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« Reply #29 on: January 10, 2014, 07:05:07 AM »

Going down the road, two 13,500btu roof tops cool the bus down to 75 just fine. When it gets over 105, then the third is kicked in. Insulation works wonders.

While working on the truck, I have a 10,000btu portable A/C that is just enough to make working in the truck tolerable in summer. Good Luck, TomC
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« Reply #30 on: January 10, 2014, 07:22:59 AM »

Hi All, has anyone used this mini split system from Artic, designed for trucks and buses? Lvmci...


http://www.arcticbreeze-truckac.com/content/busac.html
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« Reply #31 on: January 10, 2014, 07:25:08 AM »

Panasonic told Kenny the condensers need 3 ft from any structure and never install in a closed area he is trying to pull air from the bottom of the bay here the pavement in the summer time will reach 140+ degrees that causes him a problem  

 Plus he has the condensers (3) in the last bay close to the engine compartment and the engine fan over powers the small condenser fans it's a constant battle for fresh air and he is tired of the battle like anything it will take time people will get it done by the old try and fail method it will just take time  

Fwiw the people that sell the units don't really care if they work or not in mobile app just give me the money is their motto  

good luck
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« Reply #32 on: January 10, 2014, 08:32:04 AM »

How I did mine: 3 units  : 1st  condenser in spare tire compartment air in from behind bumper out thu  floor.. evap above driver seat  8 ft each of soft refrigerant copper tubing.  #2  mid ship  driverside  condenser in hvac evaporator compartment(no longer in use) forced  in from bottom side and out further up  thru same louvered door .Have not found a air recirculation prob when sitting still hear yet.  evaporator is connected by 10ft each of soft refrigerant grade copper tubing.  # 3 is located in the bedroom area facing rear.  is connected to the condenser by copper tubing 10ft each  located in the bus condenser bay which has the stock louvered door which I also elevated the condenser as high as I could drawing cool air in thru the bottom of the door and blowing discharge air out the top.. notice I did not say the underneath the bus or bottom of the bus.. When I mount  evap units I leave off level to drain end to aid in condensate drain..   This is a few things I have done plus total fastening of all line --telfon paste on fittings-- and 100% insulation on all copper.... strickly experimental!!!!!
« Last Edit: January 10, 2014, 08:35:07 AM by robertglines1 » Logged

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« Reply #33 on: January 10, 2014, 11:00:40 AM »

   Hi All, has anyone used this mini split system from Artic, designed for trucks and buses? Lvmci...

http://www.arcticbreeze-truckac.com/content/busac.html 


      A lot of things about this look good, but 850W at 24V means a draw of about 35 1/2 Amp, nominal.  To cover surges and other things (low voltage, etc.) you'd need to plan on a working max of at least 42 Amps.  Even if there's no "start-up" current draw, you'd need to wire a supply and provide fuses for about 50 Amps/24V.  That sounds like a LOT of DC current to me.  I guess with the big 50DN alternators, it might be do-able; or maybe you could do 24V converter off 120 from the generator, but -- despite the small packaging and neat design -- I wonder exactly how practical this would be.

     I'd love to hear about some real-life experience with this system.    Bruce H    NC    USA
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« Reply #34 on: January 10, 2014, 11:08:30 AM »

I'll pitch in here with my experience to help along anyone who is watching this thread -

Here are some guidelines for the Mini-Split AC install -

1. First thing first - Insulation.  Nothing beats this.  Experienced bus builders on this board have said this over and over again.  Don't skimp on insulation.  Think about windows.  Put as much insulation as you can, use quality windows.  It will make all the difference in the world.

2. Airflow - The outside condenser needs to move alot of air to stay cool.  These compressors get pretty darn hot.  Mine (with the bays open) would get up to about 115 degrees on an 85-90 degree day in Florida.  With the bays closed (Bay door had a 3' x 12" hole with a grill and the bay floor had a 2' x 1' hole to vent air out) the compressor unit would hit as high as 125 degrees.  This temperature would stay lower if the bus was moving and I mounted an exhaust fan blowing air down through the bay floor that helped as well.  Whenever we stopped overnight I would always crack the bay door 6" to help with air flow.  Keep in mind that the excessive heat on these units greatly reduces their lifespan.  Now if you use your bus 12 times a year - might not be a problem but if you live full time in your bus and use it 24/7 the heat may kill the capacitors and other parts on the outdoor unit over time.  The best direction for airfow is to bring the air in from the side of the bus and down through the floor.  This is because when the bus is moving the pressure will be higher on the sides of the bus and lower underneath which will help the fan to do less work by moving the air in the direction it would naturally flow (as opposed to against the flow).  An air damper under the bus may help with this.  I have also seen pictures of buses that had the compressor setup on one side of the bay blowing air out the other side of the bay.

3. Linesets - This is where I had the most trouble.  Installing was a pain as it was post build.  Had I done it from the beginning it would have been a lot easier.  Make sure you wrap your lines well.  They will condense and lots of water will come from them.  The better wrapped the less water.  Also - A better wrapped lineset will also help to keep the cold side cold (better cooling when it gets to the evaporator) and the hot side warm (compressor doesnt have to work as hard to compress the freon) Also make sure your linesets are tightly fastened on the outside unit.  Mine kept coming loose - could be for many reasons, suspension, vibrations, damaged threads, overtightened, undertightened... but make sure you have a good solution for fatening the linesets.  They were not designed to be used in a moving, vibrating, bouncing environment.  Maybe sweating them on would help.

4. Evaporators - These units are awesome.  Super silent, programmable, they dehumidify, cool, heat and did I say they were QUIET.  But they also put out ALOT of water.  Easily a gallon a day of water in a humid environment.  Maybe more.  These units are not designed to be on a vehicle that goes around corners and bounces all over.  So make sure you have a good solid draining system for your evaporators.  If I installed these again I would take the evaporator unit apart and make some modifications to help with the drainage.  (higher walls, multiple points of drainage) Think about how you are going to install these units...they need to pull air from above (3' of clearance) and blow air across a 15' span without anything blocking the airflow.  Anything less than this and you are decreasing the life of the units. 

You get what you pay for.  You cannot expect that a cheap 500$ mini split in a bus is going to last you more than 5 years...and if it does then your doing well.  Also parts are not going to be readily available for a cheap unit.  If parts are available it would probably cheaper to buy another unit than replace parts.  If you spend the money for a "quality"mini-split you will probably be in the same price range as what it would cost for a crusair or marine/rv style unit that is possibly battery powered or self contained and will be warrantied and have better support.

My personal belief is that most of us on these forums are looking for a cheap solution that works better and more efficient than the similarly priced roof units.  I don't think spending alot money on a top dollar mini-split system for your bus is the way to go - Rather a known and tested system (like crusair or webasto) would be the better way to spend good money.

I may be regurgitating information here that i have already shared.  In future posts, I'll just reference this and  those other posts.  For what its worth, I am not an AC, Mechanical or Electrical engineer and these are just thoughts and experiences that i am sharing along with my own opinions.

-Sean

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« Reply #35 on: January 10, 2014, 11:10:44 AM »

     A lot of things about this look good, but 850W at 24V means a draw of about 35 1/2 Amp, nominal.  To cover surges and other things (low voltage, etc.) you'd need to plan on a working max of at least 42 Amps.  Even if there's no "start-up" current draw, you'd need to wire a supply and provide fuses for about 50 Amps/24V.  That sounds like a LOT of DC current to me.  I guess with the big 50DN alternators, it might be do-able; or maybe you could do 24V converter off 120 from the generator, but -- despite the small packaging and neat design -- I wonder exactly how practical this would be.

     I'd love to hear about some real-life experience with this system.    Bruce H    NC    USA

Bruce - Not to mention they suggest no less than (6) AGM batteries - I'm assuming that they need to be about 200-300AH each and at a cost of about 400-600 per battery just the cost in batts alone will be at least $2600

-Sean

Also to note - Any 120v AC will run off batteries if you have the proper battery and inverter setup.  Technomads Chris and Cherie run their roof unit off batteries.  They also have a huge bank of Lithium Ion batteries.
« Last Edit: January 10, 2014, 11:24:13 AM by Seangie » Logged

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« Reply #36 on: January 10, 2014, 11:57:16 AM »

 Bruce - Not to mention they suggest no less than (6) AGM batteries - I'm assuming that they need to be about 200-300AH each and at a cost of about 400-600 per battery just the cost in batts alone will be at least $2600 -Sean

   Yeah, for mini-splits, I've been assuming that a bus owner would need a reasonably large generator (6K, 7.5K, 10K Huh?) generator or at least a 30 Amp shore cord supply when parked.  Obviously, this 24V unit is meant to be "stay cool for hours with parked with no external power" and thus the need for a big battery pack.  But, I see your point and agree with you.

 Also to note - Any 120v AC will run off batteries if you have the proper battery and inverter setup.  Technomads Chris and Cherie run their roof unit off batteries.  They also have a huge bank of Lithium Ion batteries.  

    Yes, and any battery-powered-AC becomes an issue of "when and how and how often" do you recharge the batteries.  I can't think of a real-life situation when someone will make enough power and have enough battery capacity to charge while driving and still have AC until you're ready to drive again.  

    It's exactly these things that are among the set of complications and situations that makes me wonder if this unit (which is also fairly small) would be sufficient or appropriate for our needs.
« Last Edit: January 10, 2014, 12:42:59 PM by Oonrahnjay » Logged

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« Reply #37 on: January 10, 2014, 12:38:36 PM »

      Yes, and any battery-powered-AC becomes an issue of "when and how and how often" do you recharge the batteries.  I can't think of a real-life situation when someone will make enough power and have enough battery capacity to charge while driving and still have AC until you're ready to drive again.  
When I install my 2,040 watts of PV panels (that will charge eight T-105 or L-16 batteries through two 60 amp MPPT charge controllers), I'll have a better idea how much usable power I'll have to run air conditioning.   Assuming the standard 0.52 derating for sun-to-AC losses, I should still get about 1,000 W of 120 V AC, about 8 amps.   It's not much compared to shore power or to what a big alternator can produce, but it's (I hope, depending on the weather) a constant, and I'll still be getting most of that even when driving.   If I can run one mini-split or window unit without pulling down the batteries I'll be happy.   We'll see!   Having lots of PV opens up some interesting possibilities.

John  
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« Reply #38 on: January 13, 2014, 07:37:59 PM »

So this proves that 2kW of solar will run a 9000 BTU minisplit:  http://www.wind-sun.com/ForumVB/showthread.php?16163-What-a-quot-cool-quot-opportunity-load-)   And without drawing down the batteries at all.   Yeah!   My crazy plan may just work.

John
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