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Tecumseh's line of compressors for solar power air conditioning? - Page 2

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Posted by Neon John on June 11, 2010, 5:23 am
 


On Thu, 10 Jun 2010 18:09:28 -0400, "vaughn"



Vaughn,

For quite some time I've been working on a scheme to air condition my
RV using battery power at night, recharged in the day by generator.
I'm a little stalled right now due to health problems but hopefully I
can get back to work on it soon.

Anyway this is what I've come up with.  The AC unit is the 16SEER DC
mini-split from here:

http://www.heatandcool.com/

Center of the page.  This is an inverter unit that has a variable
speed compressor and fan.  Of particular interest to me is that it is
transformer-less.  That is, the AC coming into the unit is immediately
rectified and filtered to about 165 volts DC.  Also of particular
interest is that the compressor soft-starts so that there is no inrush
spike.

A 12/120 volt inverter operates by first stepping the 12 volts up to
about 165 volts using a high frequency DC/DC inverter and then chops
it into a 60 hz pseudo-sine wave.

The connection should be obvious.  Tap into the inverter and bring out
the 165 volts DC and feed that into the AC.  At that point the AC can
run from 12 or 24 or whatever input voltage your inverter uses.

The AC requires no modification - the DC can be piped in directly
through the power cord.

What I've done so far.

-installed a sufficiently large battery bank in my RV
- Modified a 2kW inverter to bring the 165 volts out to a terminal
strip.
- gotten the service manual for that unit and verified from the
schematic that I can feed the DC voltage directly in.

Yet to do.

Buy a unit and hook 'em up.

I'm in the process of  building a custom motorhome using a medium duty
cube van.  It is super-insulated so that this small unit will heat and
cool the unit even in extreme weather.  Hopefully I can get back to
work on this shortly as my medical problems abate.

Anyway, you could put together something like this for not all that
much money.  The solar panels would be the big expense but perhaps you
could find some surplus/used.  Even if the solar panels could not
supply all the operating power, they could help out.  Just wire up a
suitably sized RV converter (Progressive Dynamics Intellipower/Charge
Wizard is my favorite) to supply power from the line to the inverter.

John

Posted by vaughn on June 11, 2010, 1:04 pm
 




If you look at the 13 SEER unit on that page, you are looking s something so
close to my bedroom unit that I am willing to bet they shared the same Asian
factory.  Mine came from here:
http://www.comfort-aire.com/residential/17-ductless-mini-split-systems/45-s-series-single-zone  
They seen to have about the same product mix.  I ended up with the 13 SEER unit
because mine was a "bother-in-law" deal and that was what I was offered!  I
managed to install it myself in only about 10X the time a professional would
have taken, but am happy with the results.  It did not have pre-charged lines,
so you need a vacuum pump to install.  That turned out to be good for me because
it helped me detect a leak in one of my flare connections before I lost any
refrigerant. (I would love to replace the window shaker in our study with
another of those units, but it really is hard to justify.)

I have long suspected that "inverter" ACs actually ran on DC, but there really
is very little information on them.  Actually, almost anything with a
transformerless switching power supply should be convertible to DC.  The main
question is what range of DC inputs can be tolerated.  Finding the answer via
the experimental method could be expensive!

John, please keep us informed on that project.

Vaughn
 



Posted by Martin Riddle on June 12, 2010, 3:35 am
 




http://www.comfort-aire.com/residential/17-ductless-mini-split-systems/45-s-series-single-zone  

If the AC line specs are 120v +/- 10%  then 152 volts DC is the low end
of the required input.  Which should fall into the range of of the +buss
of of a MSW inverter. Don't forget depending upon the inverter, you'll
only need the + buss voltage as most MSW inverters have + and - 165vdc
(it's probably closer to 150vdc for a MSW).

Cheers



Posted by Josepi on June 12, 2010, 3:49 am
 

http://en.wikipedia.org/wiki/Buss


If the AC line specs are 120v +/- 10%  then 152 volts DC is the low end
of the required input.  Which should fall into the range of of the +buss
of of a MSW inverter. Don't forget depending upon the inverter, you'll
only need the + buss voltage as most MSW inverters have + and - 165vdc
(it's probably closer to 150vdc for a MSW).

Cheers




Posted by vaughn on June 12, 2010, 11:03 am
 



Oops!  Would that limit you to half power from the inverter?

Vaughn



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