AC requirements for a heat wimp...???

[mpruet]

OK - I admit that I'm a bit of a wimp when it comes to having air conditioning - and that's pretty bad for a boy that grew up in Alabama and vividly remember scraping tar off of my feet at night from walking barefoot in the summer on asphalt roads that had melted in the southern sun...

I currently have a class-A that I'm trying to sell and have been car camping in a Prius this summer.  It's simply too much of a hassle to get the class-A set up for a trip.  I like the spontaneity and freedom to just get up and go. I'm not a full time nomad, but am retired and want to be able to travel all around the nation. It's rather difficult to be stealth in a class-A and I like to boondock - both in the country as well as in the city.  The Prius is ideal at being stealth, but is a bit tight when it comes to getting dressed.  Also I'd like to be able to cook indoors - especially when boondocking and the bugs are in attack mode...

So I'm contemplating doing a cargo van conversion.  However, I really like that I can keep the Prius on at night and run the AC.  I love being able to sleep in a cool room.  I've thought about the possibility of getting a swamp cooler for a van.  As long as I'm in the southwest that would work fairly well, but would also require access to more water which could be an issue in the desert.  Also, I want to be able to go to the southeast without melting and swamp coolers are kinda worthless there.  I still remember those hot nights from my youth and doubt that a fan system would work.  So I feel that I need to explore what kind of solar/battery/AC unit I would need to at least be able to sleep through the night. 

I know that some folks in this group have been successful at setting up AC running on battery power.  Since I am still in the 'dreaming/thinking' stage, I'd like some input into what type of battery bank/ solar system I'd need to make this sort of thing work.  The only other overnight power usage that I would need would be to power my fridge - 18 L dometic compressor fridge which uses less than 1 amp an hour.  (I already have that in my Prius camping and would like to continue to use.)

Thanks

 

[John61CT]

setting up AC running on battery power.  Since I am still in the 'dreaming/thinking' stage, I'd like some input into what type of battery bank/ solar system I'd need to make this sort of thing work.

To be honest the ideal power setup would be your Prius, towed behind a 3500 van or truck. Not stealth when together, but maybe choose one or the other for stealthing in?

 

[jonsun]

get a prius battery pack for the van?

 

[mpruet]

To be honest the ideal power setup would be your Prius, towed behind a 3500 van or truck. Not stealth when together, but maybe choose one or the other for stealthing in?

HA!!  

I'm trying to simplify my traveling.  I hate having to have a tow car on the class-A.  Towing a Prius would require a platform dolly as they are not supposed to be towed with wheels on the ground.  It's part of the breaking (or downhill) energy recapture system...

 

[mpruet]

get a prius battery pack for the van?

wouldn't work. 

The big volt battery is used to charge the smaller 12-volt battery which in turn runs just about everything else.  When the capacity of the big volt battery drops to a certain level, a sensor automatically starts gas engine which in turn recharges the big volt battery a bit.  If you just had the big volt battery, then at night it would fully drain as there wouldn't be an engine to start...

 

[John61CT]

Yes it's Toyota’s unique hybrid synergy drive system that is the secret sauce, not the bank.
The petrol engine drives the generator to charge the battery very quickly, efficiently and quietly.

 

[John61CT]

Running A/C for more than a few hours a day cannot be "solar A/C" in most mobile setups.

Obviously max out your roof space on panels, but best you can hope for IMO is reducing your generator usage a bit, and having some choice about the timing of your run hours.

The bigger the bank the better, for most setups space and weight limits, but 600-800AH is a good start IMO, double that if you can.

Of course moving to where the weather is cooler. . .

 

[John61CT]

Relevant recent thread

Is this the holy grail of RV/van Air Conditioners? DC Airco
https://vanlivingforum.com/showthread.php?tid=25482

 

[mpruet]

Yes it's Toyota’s unique hybrid synergy drive system that is the secret sauce, not the bank.
The petrol engine drives the generator to charge the battery very quickly, efficiently and quietly.

True - but I'm not trying to move my Prius into a van, I just want to be able to sleep at night.  I don't really care what I need to do.  I can probably keep the temp around 80 with no problem - just don't want to wake up all sweaty....  

 

[John61CT]

The real key is super insulation, like 6-8" all round, sealed door, no windows.

Sometimes you see reefer delivery/box trucks available for decent pricing.

I missed out on a gov auction of a portable morgue vehicle in great shape, included the generator installed, unfortunately I got outbid I think ended up going for $9K or so, very low miles.

 

[mpruet]

Running A/C for more than a few hours a day cannot be "solar A/C" in most mobile setups.

Obviously max out your roof space on panels, but best you can hope for IMO is reducing your generator usage a bit, and having some choice about the timing of your run hours.

The bigger the bank the better, for most setups space and weight limits, but 600-800AH is a good start IMO, double that if you can.

Of course moving to where the weather is cooler. . .

Thanks ---

I'm not planning on going full-time nomad.  I just want to be able to boondock during my trips.  One of my 'home bases' is in a condo that I have in the Colorado Rockies at 9K feet so I know the importance of altitude.  I need to be able to park whatever I end up with in a normal parking space.  Just trying to get ideas so I know whether it is even feasible to do this.

 

[mpruet]

Relevant recent thread

Is this the holy grail of RV/van Air Conditioners?  DC Airco
https://vanlivingforum.com/showthread.php?tid=25482

Thanks

 

[mpruet]

The real key is super insulation, like 6-8" all round, sealed door, no windows.

Sometimes you see reefer delivery/box trucks available for decent pricing.

I missed out on a gov auction of a portable morgue vehicle in great shape, included the generator installed, unfortunately I got outbid I think ended up going for $9K or so, very low miles.

Do you know of any DC systems that would work?  I'd like to avoid the power loss that inversion introduces.

 

[John61CT]

Packaged systems where you don't need to learn about the tech at all will cost many times just putting the various components together.

Assuming you're away from shore power for several days, your setup will need to be the same as full-time living, just that you probably won't put in as big an investment on top quality electric gear, say $3K rather than 7.

Carrying a little 1000w generator lets you use A/C more than just a few hours, but a 3-4k unit will mean not running it so many hours per day, if you're willing to go to a bigger truck.

 

[highdesertranger]

in another month you won't have to worry about AC for about 6 months. highdesertranger

 

[jonyjoe303]

For night time all you need is a swampcooler, this week the humidity has been in the 70's, in the daytime the swampcooler was barely keeping me cool. As long as I stayed in the comfort zone (right next to swampcooler) I was cool, once I left that zone I was sweating.

It's been hot enough that I had to run the swampcooler all night long. But at night I throttle it down to less than 1 amp. Also at night it doesnt use that much water. All week as hot as it was I was averaging about 3 to 4 liters of water per day and thats running the swampcooler almost 24 hours every day.

It helps if you have your van well insulated. The entire rear of my van has between 1 and 2 inches of foam insulation. I got the front and rear of my van isolated with a insulated sliding door. It can be 140 in the front of the van and only 98 degrees in the back, still hot but livable if your next to the swampcooler and this is parked in the sun. 

In 4 years I haven't encounter a day hot enough that my swampcooler couldn't keep up with it. Once or twice I had a fan or pump on the swampcooler fail, those few minutes without a swampcooler can be brutal, luckily I can fix it quickly.

For AC the hurriedyear website shows you how to build your own AC system running off batteries and solar. The batteries (260 ah x 3) alone are almost 500 pounds. And he has almost 800 watts of solar. 

But also something that might be available later in the year is the "zero breeze" portable AC that will run 5 hours on it's built-in battery. It was suppose to be available in march but has been delayed. That might be something to look into. Something like that would run on a more modest solar system.

my swamp cooler

 

[sushidog]

Do you know of any DC systems that would work?  I'd like to avoid the power loss that inversion introduces.

That 9,000 Btu Airco draws 600 watts for an EER of 15. (50 amps at 12v)

This 12,000 Btu mini-split draws 560 watts for an EER of 21.43. http://www.geinnovations.net/HSAC_Productline.html

It is a 48v DC system so there is no inverter loss, but requires at least a 48v battery bank (at least 4, 12v AGM batteries wired in series, but I recommend 8 - GC2 golf cart batteries to power it pluss other things you may need.) drawing 11.5 amps at 48v.

8 golf cart batteries will give you 110 usable amp hours so you could power this 12,000 Btu AC for 9 1/2 hours continuously till they are at a 50% charge. The real key here is that a 12,000 Btu AC with a rotary compressor doesn't cycle like a conventional compressor, but scales its output and power draw when less cooling is needed, as it will be even in a poorly insulated van with 12,000 Btus of cooling power available. So in all likelihood your AC will only be drawing half the max current after the van gets cool, say 6 amps. That means the AC could run twice as long (or you could go to a smaller battery bank.) 

You could recharge these batteries however you like, from solar, wind or a generator. You would need at least 1000 watts of solar panels to recharge the batteries or you could use a combination of recharge sources, say 600 watts of solar (if that's all you could fit on the roof) and a small generator. You are looking at a very expensive system though, as the AC alone will run you around $2,000. If you choose a generator to recharge I recommend getting a 48v inverter/charger like this for another $520. https://www.sigineer.com/product/3000-watt-inverter-charger-48-volt-110v-120vac-pure-sine-wave/ It has a built-in 30 amp charger (so you'd need at least a 2,000 watt generator, like thr Honda EU2000) plus as a side benefit, you will have clean, pure sine wave 120v ac available to run other things as needed.

I am planning on using this AC to partially cool a medium sized Class A (mainly the bedroom so DW and I can sleep well at night) when I go FT in a year and a half with 8 GC-2s and about 2,000 watts of flat mounted solar (now that it's so cheap - less than 50 cents/watt here http://sunelec.com/home/ .)

Chip

 

[John61CT]

That sounds like a realistic setup.

Stepping the 48V down to a 12V House circuit for other devices needs to be taken into account as well.

 

[John61CT]

YouTube just popped this up into my feed https://www.practicalpreppers.com/air-conditioning/dc-air-conditioner-all-dc-for-off-grid-use

 

[IGBT]

That sounds like a realistic setup.

Stepping the 48V down to a 12V House circuit for other devices needs to be taken into account as well.

I tap off one of the 12V batteries in my 24V system and you could do similar in a 48V system.  I use a Vanner Equalizer which provides 60 amps at 12V.