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Yep - they're group 27. We had this discussion and you showed me your group 31 battery and that's probably why it's stuck in my head.

Thanks for doing the math - my napkin math came out to 2.23 so we're pretty close. Thing is, that assumes 100% cycle. In a 80 square foot space with 8000 btu assuming a low approximate R value of 2.5 ? and an ambient temperature of X degrees and intermittent sun... I would assume that even on low it's going to be cycling on and off a lot. So, one should question the impact of a fat guy sweating in there....And realize there's too many variables.

The other thing is the solar panels. I figure for most camping excursions, I'm out of the trailer all day and the sun is charging up my batteries.

This calculator is pretty cool. Found it after I did the math above:

BatteryStuff Tools | Solar Calculator

It tells me in order to run the AC for 7 hours a day on low I'd need 12 - 100w panels :)

With my current configuration, and a desire to not drain the batteries - I would get 35 minutes a day of AC assuming I also get 8 hours of full sun.... riiiiight.

I'm gonna be getting another panel or two, I guess :)
 
jamesurq said:
Yep - they're group 27. We had this discussion and you showed me your group 31 battery and that's probably why it's stuck in my head.

Thanks for doing the math - my napkin math came out to 2.23 so we're pretty close. Thing is, that assumes 100% cycle. In a 80 square foot space with 8000 btu assuming a low approximate R value of 2.5 ? and an ambient temperature of X degrees and intermittent sun... I would assume that even on low it's going to be cycling on and off a lot. So, one should question the impact of a fat guy sweating in there....And realize there's too many variables.

The other thing is the solar panels. I figure for most camping excursions, I'm out of the trailer all day and the sun is charging up my batteries.

This calculator is pretty cool. Found it after I did the math above:

BatteryStuff Tools | Solar Calculator

It tells me in order to run the AC for 7 hours a day on low I'd need 12 - 100w panels :)

With my current configuration, and a desire to not drain the batteries - I would get 35 minutes a day of AC assuming I also get 8 hours of full sun.... riiiiight.

I'm gonna be getting another panel or two, I guess :)
Click to expand...


It sounds like without getting crazy on the solar panels you might be doing okay. 2 hours of storage is "run time" which, with a little insulation, could be brought down to a pretty small number.

LED lighting won't even register as far as drain is concerned so all you have left is fridge.
 
The fridge is definitely a wildcard. Contents, ambient temperature, etc.... we'll see.

I've thought about insulation for the ceiling but don't want to lose too much of the ceiling height. Was thinking of the thin stick on insulation with the foil backing - same stuff I used on the floor. Not crazy about having a foil ceiling though.
 
Go this route so you don't destroy The ambience

IMG_6932.JPG
 
I thought you were putting a small generator on the trailer? If so, all of this is pretty much a moot point, no?
 
I have a generator - but I'd prefer not to use it. noisy, heavy, smelly...
 
But isn't utilizing fossil fuels to generate electricity by definition "looking back"?

I'd rather look up :) (solar)....
 
How bout 3/4 inch pink foamular insulation for up there? It will give you a little bit of R value, better than a non insulated roof. You wont lose much ceiling height.
 
stevezero said:
How bout 3/4 inch pink foamular insulation for up there? It will give you a little bit of R value, better than a non insulated roof. You wont lose much ceiling height.
Click to expand...
Yeah - thought about the pink stuff. Used a bunch of it in the past on fish tank insulation projects.

Maybe. don't really like the idea of losing any ceiling height though.
 
jamesurq said:
Yeah - thought about the pink stuff. Used a bunch of it in the past on fish tank insulation projects.

Maybe. don't really like the idea of losing any ceiling height though.
Click to expand...

I have no idea how much R-value this would give but I imagine some self-adhesive sound deadening/firewall lining would help a bit. Should be easy to install over an irregular surface and have minimum thickness.

Thermo-Tec Acoustical & Heat Control Mats 14610
 
i put some of the the foil backed butyl "ac duct wrap" they sell at the box stores in the 4r and white 80. It helps a bit with resonance, and probably a bit of insulation. Would definitely be a wise use of a 2 or 3 rolls (about $50) worth
 
I actually used the Thermo King duct insulation on the floor - it's likely what I'll use on the ceiling. Similar to what you're suggesting Rice, but quite a bit cheaper. Don't like the look of it though, I'll have to figure something out aesthetically.
 
Have you considered going 12v DC to be more efficient on the AC? I don't know the "math/physics" behind the savings vs inverter, so I too am kind of "baiting" (not my word!) @Rice here :)

Wonder if those units are less efficient to begin with so may be a "wash" vs the inverter.

The Prius touted its electrical AC as a big technology hurdle - not that it applies here, but wonder what Toyota did there. If you let the Prius sit with AC, it does take the main battery down pretty quick.
 
weejub said:
Have you considered going 12v DC to be more efficient on the AC? I don't know the "math/physics" behind the savings vs inverter, so I too am kind of "baiting" (not my word!) @Rice here :)

Wonder if those units are less efficient to begin with so may be a "wash" vs the inverter.

The Prius touted its electrical AC as a big technology hurdle - not that it applies here, but wonder what Toyota did there. If you let the Prius sit with AC, it does take the main battery down pretty quick.
Click to expand...
Not sure the improvements in efficiency - but certainly a roof mounted 12v AC would be the best choice for space and avoids cutting a hole like I did. However. They're not cheap.
 
jamesurq said:
Not sure the improvements in efficiency - but certainly a roof mounted 12v AC would be the best choice for space and avoids cutting a hole like I did. However. They're not cheap.
Click to expand...

There really is no such thing as an AC solar panel, i.e. the panel itself only makes DC. What has come to market are panels that have inverters integrated into the package. So you end up paying for an inverter one way or the other. The 90% inverter efficiency I tossed out earlier really is rather low ... most tend to be closer to 95%, so losses there are small.

James the only thing I can think of that you might be unhappy with is the "overkill" size of the AC unit. Because the trailer is so small and is cooled down in just a couple minutes that doesn't give the AC unit any time to pull out humidity from the air ... the same thing that happens when people put oversized units in their houses (A topic perhaps @Roxx can help us on). Otherwise it sounds like other than some insulation you're ready to go "camping".
 
Tried really hard to find something smaller in a non window unit and they don't exist. 4000 btu is basically the smallest I found. It's $99 and it's a window unit. And I have one already that I use for the big cabin tent.

Yeah, so I 'camp'.... I 'camp' hard.
 
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